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Sample records for az31 mg alloy

  1. Self-assembled monolayers formed on AZ31 Mg alloy

    Science.gov (United States)

    Salman, S. A.; Okido, M.

    2012-07-01

    Self-assembled monolayer (SAM) was successfully adsorbed on the AZ31 Mg alloy surface using oleic acid and stearic acid with various organic solvents, such as acetone, ethanol, and hexane. The surface monolayers were characterized using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and anodic polarization test. It was shown that the higher contact angle and the best anti-corrosion property were obtained with treatment in oleic acid with ethanol solution.

  2. Microstructure and mechanical properties of AZ31 Mg alloy processed by high ratio extrusion

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-jun; WANG Qu-dong; LIN Jin-bao; ZHANG Lu-jun; ZHAI Chun-quan

    2006-01-01

    The microstructure and mechanical properties of AZ31 Mg alloy processed by high ratio extrusion (HRE) were investigated. General extrusion with extrusion ratio of 7 and high ratio extrusion with extrusion ratio 100 were contrastively conducted at 250, 300 and 350 ℃. The results show that HRE process may be applied successfully to AZ31 Mg alloy at temperatures of 250, 300 and 350 ℃ and this leads to obvious grain refinement during HRE process. The strength of HRE process is improved obviously compared with that of general extrusion. The grain refining mechanism of HRE process was also discussed. The current results imply that the simple high ratio extrusion method might be a feasible and effective processing means for refining the microstructure and improving the mechanical properties of AZ31 Mg alloy.

  3. Electrochemical polymerization of pyrrole over AZ31 Mg alloy for biomedical applications

    International Nuclear Information System (INIS)

    Highlights: ► Polymerization of pyrrole over AZ31 Mg was carried out using cyclic voltammetry. ► Pyrrole concentration was optimized to accomplish the adherent and uniform coating. ► Effect of monomer concentration on the surface morphology was discussed. ► Corrosion resistance of AZ31 Mg in SBF was studied as a function of Py concentration. ► PPy coated AZ31 Mg alloy exhibited enhanced corrosion resistance at 0.25 M of Py. -- Abstract: Electrochemical polymerization of pyrrole (Py) from aqueous salicylate solution over AZ31 Mg alloy was carried out using cyclic voltammetry (CV). The effect of monomer concentration on the surface and electrochemical corrosion in simulated body fluid (SBF) were analysed. Attenuated total reflection-infrared (ATR-IR) spectra showed the characteristic ring stretching peaks for polypyrrole (PPy). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited typical cauliflower morphology with rough surface for PPy coated AZ31 Mg alloy. Open circuit potential measurement and potentiodynamic polarization studies revealed that the coating prepared using 0.25 M of Py had positive shift of about 120 mV in corrosion potential and lower corrosion current density (0.03 mA/cm2) compared to other concentrations and uncoated AZ31 Mg alloy (0.25 mA/cm2). Electrochemical impedance spectroscopic (EIS) studies of uncoated and PPy coated Mg alloy in SBF revealed three-time constants behaviour with about one order of increment in impedance value for 0.25 M of Py

  4. Joining of AZ31 and AZ91 Mg alloys by friction stir welding

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2015-12-01

    Full Text Available Two dissimilar magnesium (Mg alloy sheets, one with low aluminium (AZ31 and another with high aluminium (AZ91 content, were successfully joined by friction stir welding (FSW. The effect of process parameters on the formation of hot cracks was investigated. A sound metallurgical joint was obtained at optimized process parameters (1400 rpm with 25 mm/min feed which contained fine grains and distributed β (Mg17Al12 phase within the nugget zone. An increasing trend in the hardness measurements has also confirmed more amount of dissolution of aluminium within the nugget zone. A sharp interface between nugget zone and thermo mechanical affected zone (TMAZ was clearly noticed at the AZ31 Mg alloy side (advancing but not on the AZ91 Mg alloy side (retreating. From the results it can be concluded that FSW can be effectively used to join dissimilar metals, particularly difficult to process metals such as Mg alloys, and hot cracking can be completely eliminated by choosing appropriate process parameters to achieve sound joint.

  5. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    OpenAIRE

    I.B. Singh; M Singh; Das, S.

    2015-01-01

    The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals sh...

  6. Electrochemical study of modified bis-[triethoxysilylpropyl] tetrasulfide silane films applied on the AZ31 Mg alloy

    International Nuclear Information System (INIS)

    This work investigates the protective behaviour of bis-[triethoxysilylpropyl] tetrasulfide silane pre-treatments on the AZ31 Mg alloy. The silane solution was modified by the addition of cerium nitrate or lanthanum nitrate in order to introduce corrosion inhibition properties in the silane film. The corrosion behaviour of the pre-treated AZ31 magnesium alloy was studied during immersion in 0.005 M NaCl solution, using electrochemical impedance spectroscopy and the scanning vibrating electrode technique (SVET). The electrochemical experiments showed that the presence of cerium ions or lanthanum ions improve the protective behaviour of the silane film. The SVET experiments evidenced that the presence cerium in the silane film led to an important reduction of the corrosion activity. The results demonstrate that either cerium ions or lanthanum ions can be used as additives to the silane solutions to improve the performance of the pre-treatments for the AZ31 magnesium alloy

  7. Effects of hot extrusion and annealing treatment on microstructures,properties and texture of AZ31 Mg alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; YAN Yun-qi; WENG Wen-ping; ZHONG Hao; CHEN Qi

    2006-01-01

    Effects of extrusion deformation and heat treatment on microstructures, mechanical properties and texture of AZ31 Mg alloy were investigated.The results show that the microstructures of as-cast AZ31 alloy are markedly refined after hot extruding, the average grain size is about 25 μm and strong fiber texture exists in the extruded AZ31 alloy. The mechanical properties are improved obviously. The grain size is somewhat inhomogeneous and strip structure emerges along the extrusion direction due to incomplete dynamic recrystallization during the extrusion process. With increasing annealing temperature, the small grain grows up and turns into equiaxed grain, and the texture is weakened with the visible growing up of grains.

  8. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

    Institute of Scientific and Technical Information of China (English)

    Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

    2009-01-01

    Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

  9. Microstructure and properties of hot extruded AZ31-0.25%Sb Mg-alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of hot extrusion treatment on the microstructure and mechanical properties of AZ31-0.25%Sb Mg alloy were mvestlgated by means of mechanical properties measurement and microstructure observation.The results show that the (UTS) and yield tensile strength(YTS) of the alloy are obviously enhanced by hot extrusion treatment,and the enhanced extent of UTS and YTS increases with the decrease of hot extrusion temperature,moreover,the YTS value of the alloy at RT,after extruded at 220℃,increases up to 131.4%,which attributes to the finer grains resulted from the dynamic recrystallization occurred during hot extrusion.As not extrusion goes on,the slipping and concentration of dislocations continue to occur within the finer grains,which promotes the formation of the subgrains in the alloy.The deformation features of the extruded alloy during tensile deformation at RT are the twinning deformation and dislocation slipping in the twinning regions.Moreover,the deformation mechanisms of the alloy are a dislocation activation on the basal plane and a+c dislocation activation on the pyramidal planes.

  10. Microstructure and properties of welds between 5754 Al alloys and AZ31 Mg alloys using a Yb:YAG laser

    Science.gov (United States)

    Bannour, Sana; Autric, Michel; Masse, Jean-Eric; Mattei, Simone; Mhiri, Hatem

    2015-02-01

    Dissimilar laser beam welding between A5754 Al alloys and AZ31 Mg alloys with the plate thickness of 2 mm was investigated. Complex flow pattern characterized by a large volume of intermetallic compounds Al12Mg17 and Al3Mg2 is formed in the fusion zone. Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld, and the maximum value of microhardness in the fusion zone is much higher than of the base materials.

  11. Microstructure and properties of welds between 5754 Al alloys and AZ31 Mg alloys using a Yb:YAG laser

    OpenAIRE

    BANNOUR, Sana; Autric, Michel; MASSE, Jean-Eric; MATTEÏ, Simone; Mhiri, Hatem

    2014-01-01

    Dissimilar laser beam welding between A5754 Al alloy and AZ31 Mg alloy with the plate thickness of 2 mm was investigated. Complex flow pattern characterized by a large volume of intermetallic compounds Al12Mg17 and Al3Mg2 is formed in the fusion zone. Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld, and the maximum value of microhardness in the fusion zone is much higher than of the base materials.

  12. Electrochemical Investigations of Polycaprolactone-Coated AZ31 Mg Alloy in Earle's Balance Salt Solution and Conventional Simulated Body Fluid

    Science.gov (United States)

    Wilke, Benjamin M.; Zhang, Lei

    2016-06-01

    Polycaprolactone (PCL) coating has been shown to increase the corrosion resistance of magnesium alloys when exposed to a simulated body fluid. A PCL dip coating was applied to AZ31 Mg alloy. Samples were immersed in both Earle's Balance Salt Solution (EBSS) and conventional simulated body fluids (c-SBF) up to 14 days. Microscopic morphology, electrochemical impedance spectroscopy, and potentiodynamic polarization tests were performed to evaluate the corrosion behavior changes of PCL coatings against immersion times in EBSS and c-SBF as compared to the uncoated AZ31 substrate. PCL-coated samples demonstrated improved corrosion resistance compared to bare AZ31 in both EBSS and c-SBF, indicating that the PCL coating exhibited good corrosion protection of AZ31 in simulated body fluid. Samples immersed in EBSS showed significantly higher electrochemical impedance values and slower corrosion progression as compared to the samples in c-SBF, because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

  13. The research on the effect of MgCO{sub 3} on the grain refinement in AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, S.Y.; Cui, J.Z.; Li, Q.C.; Zhang, Z.Q. [Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang (China)

    2010-08-15

    The effect of MgCO{sub 3} addition on the as-cast microstructure of AZ31 magnesium alloy has been widely investigated. The results show that the average grain size of the {alpha}-Mg grain in AZ31 magnesium alloy decreases from about 570 {mu}m to 100 {mu}m by the addition of 0.6 wt.% MgCO{sub 3} as gain refiner at 760 C. Based on the analysis of EDS, theoretical calculation of E{sub bind} and Gibbs free energy, we esteem that grain refiner mechanism is mainly attributed to the generation of Al{sub 4}C{sub 3}, which can be serviced as nucleation site and restrain grain boundary from growing and transferring. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  14. On the cold rolling of AZ31 Mg alloy after Equal Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Seyed Mohammad Arab

    2014-09-01

    Full Text Available Among the various Severe Plastic Deformation (SPD processes, Equal Channel Angular Pressing (ECAP is one of the most applicable one which improves strength and ductility due to grain refinement and suitable texture development. In this study, cold rolling were carried out on the 4 pass ECAPed (in route A and C strip shaped specimens of AZ31 magnesium alloy to investigate the ECAP effects on the roll-ability. Results showed that reduction in area which can be concerned as an index for roll-ability increased after ECAP. It was also seen that ECAP in route C enhanced roll-ability more than route A.

  15. On the cold rolling of AZ31 Mg alloy after Equal Channel Angular Pressing

    OpenAIRE

    Seyed Mohammad Arab; Abbas Akbarzadeh

    2014-01-01

    Among the various Severe Plastic Deformation (SPD) processes, Equal Channel Angular Pressing (ECAP) is one of the most applicable one which improves strength and ductility due to grain refinement and suitable texture development. In this study, cold rolling were carried out on the 4 pass ECAPed (in route A and C) strip shaped specimens of AZ31 magnesium alloy to investigate the ECAP effects on the roll-ability. Results showed that reduction in area which can be concerned as an index for roll-...

  16. Corrosion resistance of anodized AZ31 Mg alloy in borate solution containing titania sol

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yan; Wang Guixiang [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Dong Guojun [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: dgj1129@163.com; Gong Fan; Zhang Lili; Zhang Milin [Key Laboratory of Superlight Material and Surface Technology, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2008-09-08

    Anodic films were prepared on the AZ31 magnesium alloy in alkaline borate solution with or without addition of titania sol under the constant potential of 50 V (dc) for 10 min at room temperature. The morphology of the anodic films was observed by scanning electron microscope (SEM). The corrosion resistance of the anodic films was evaluated in 3.5% NaCl solution using fast anti-acid test, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The anodic film formed in borate solution with addition of 4% titania sol has superior uniform surface and higher corrosion resistance than in other conditions.

  17. Mechanical and microstructural evolution of Mg AZ31 alloy using ECASD process

    OpenAIRE

    Daniel Peláez; Cesar Isaza; JUAN M. MEZA; Patricia Fernández-Morales; Wociech Z. Misiolek; Emigdio Mendoza

    2015-01-01

    A continuous severe plastic deformation (SPD) technique called equal-channel angular sheet drawing (ECASD) was used to mechanically deform an annealed magnesium AZ31B alloy. Samples of 2.45 mm thickness by 50 mm width and 200 mm in length were cut from a sheet and then submitted to two different ECASD routes: route A: the sample is not rotated around its axis and, route C: the sample is rotated 180° around its axis between passes. The samples were held up to six ECASD passes at room temperatu...

  18. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    Directory of Open Access Journals (Sweden)

    I.B. Singh

    2015-06-01

    Full Text Available The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals showed a decrease of corrosion rate with immersion time, suggesting the formation of a protective layer on their surfaces. In contrast, the corrosion current density (Icorr derived from the Tafel plots, exhibited their corrosion resistances in order of Mg > AZ91 > AZ31. Electrochemical charge transfer resistance (Rct and double layer capacitance measured by electrochemical impedance spectroscopy (EIS, are well in accordance with the measured Icorr. EIS measurements with time and microstructural examination of the corroded and uncorroded samples are helpful in elucidation of results measured by electrochemical polarization.

  19. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Mukhametkaliyev, T., E-mail: mtm91@mail.ru; Surmeneva, M., E-mail: feja-mari@yandex.ru; Surmenev, R., E-mail: rsurmenev@gmail.com [National Research Tomsk Polytechnic University (Russian Federation); Mathan, B. K., E-mail: bobby.mathan@jcu.edu.au [James Cook University, Townsville (Australia)

    2015-11-17

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density I{sub corr} reduced by ∼ 98% as compared to the base alloy.

  20. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    International Nuclear Information System (INIS)

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density Icorr reduced by ∼ 98% as compared to the base alloy

  1. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    Science.gov (United States)

    Mukhametkaliyev, T.; Surmeneva, M.; Surmenev, R.; Mathan, B. K.

    2015-11-01

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density Icorr reduced by ˜ 98% as compared to the base alloy.

  2. Effect of grain size distribution and texture on the cold extrusion behavior and mechanical properties of AZ31 Mg alloy

    International Nuclear Information System (INIS)

    Research highlights: → Microstructure and mechanical properties of fine-grained AZ31 Mg alloys were studied. → The initial homogeneous microstructure led to homogeneous cold deformation. → Texture softening effect on yield strength overcame fine-grain strengthening effect. → Well-distributed grain size reduced the absolute difference of yield strength. - Abstract: An experimental investigation into the cold extrusion and the subsequent annealing processes of an Mg-2.8%Al-0.83%Zn (AZ31) Mg alloy was studied. Microstructures, grain size distribution and texture evolution of the as-extruded and as-annealed specimens were investigated by optical microscopy and electronic backscattered diffraction (EBSD). Tensile tests along the extrusion direction were carried out at room temperature. It is found that firstly, the uniform microstructure with log-normal grain size distribution led to homogeneous cold deformation and good appearance without cracks for the as-extruded rods; secondly, texture was able to soften the yield strength induced by grain refinement and even overcame the refined grain size effect; thirdly, well-distributed microstructure reduced the absolute difference of yield strength for the sub-micrometer-grain Mg alloys.

  3. Effect of Rolling Route on Microstructure and Tensile Properties of Twin-Roll Casting AZ31 Mg Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Dan Luo

    2016-06-01

    Full Text Available Twin-roll casting AZ31 Mg alloy sheets have been fabricated by normal unidirectional-rolling, head-to-tail rolling, and clock-rolling, respectively. It has been demonstrated that head-to-tail rolling is the most effective to refine the microstructure and weaken the basal texture among the three rolling routes. Excellent integrated tensile properties can be obtained by the head-to-tail rolling. The yield strength, ultimate tensile strength, and plastic elongation are 196 MPa, 301 MPa, and 28.9%, respectively. The strength can benefit from the fine grains (average value of 4.0 μm of the AZ31 alloy processed by the head-to-tail rolling route, while the excellent plastic elongation is achieved owing to the weakened basal texture besides the fine grains. Results obtained here can be used as a basis for further study of some simple rolling methods, which is critical to the development of Mg alloys with high strength and plasticity.

  4. Mechanical and microstructural evolution of Mg AZ31 alloy using ECASD process

    Directory of Open Access Journals (Sweden)

    Daniel Peláez

    2015-10-01

    Full Text Available A continuous severe plastic deformation (SPD technique called equal-channel angular sheet drawing (ECASD was used to mechanically deform an annealed magnesium AZ31B alloy. Samples of 2.45 mm thickness by 50 mm width and 200 mm in length were cut from a sheet and then submitted to two different ECASD routes: route A: the sample is not rotated around its axis and, route C: the sample is rotated 180° around its axis between passes. The samples were held up to six ECASD passes at room temperature (RT. The processing speed was set at 20 mm/min for both routes. The mechanical properties and the micro-structural evolution were studied as a function of the number of passes, and processing route; tensile and hardness tests were used for this purpose. A grain size refinement is achieved from the first pass for both routes, being the grain refinement more marked for route A; at the last passes is evident the presence of twins. Hardness had shown a remarkable increase in each pass. It was found that the route C produces better uniform hardness distribution through the thickness of the samples when is compared with route A. Nevertheless, ultimate tensile strength (UTS and yield strength (YS are inconsistent with the Hall–Petch relationship. It could be due to a higher rate of texture softening verses the strengthening effects of the grain refinement.

  5. Enhancing Microstructure and Mechanical Properties of AZ31-MWCNT Nanocomposites through Mechanical Alloying

    OpenAIRE

    B.K.Raghunath; Rao, T H; Jayakumar, J.

    2013-01-01

    Multiwall carbon nanotubes (MWCNTs) reinforced Mg alloy AZ31 nanocomposites were fabricated by mechanical alloying and powder metallurgy technique. The reinforcement material MWCNTs were blended in three weight fractions (0.33%, 0.66%, and 1%) with the matrix material AZ31 (Al-3%, zinc-1% rest Mg) and blended through mechanical alloying using a high energy planetary ball mill. Specimens of monolithic AZ31 and AZ31-MWCNT composites were fabricated through powder metallurgy technique. The micro...

  6. The relationships between residual stress relaxation and texture development in AZ31 Mg alloys via the vibratory stress relief technique

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jia-Siang, E-mail: andy304312003@yahoo.com.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Hsieh, Chih-Chun, E-mail: jeromehsieh@gmail.com [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Lai, Hsuan-Han, E-mail: g099066020@mail.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Kuo, Che-Wei, E-mail: teancumxwei@facebook.com [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Wu, Paxon Ti-Yuan, E-mail: paxon1992911@gmail.com [Department of Mechanical Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Wu, Weite, E-mail: wwu@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China)

    2015-01-15

    A systematic study of residual stress relaxation and the texture evolution of cold-rolled AZ31 Mg alloys using the vibratory stress relief technique with a simple cantilever beam vibration system was performed using a high-resolution X-ray diffractometer and a portable X-ray residual stress analyzer. The effects of vibrational stress excitation on the surface residual stress distribution and on the texture of pole figures (0002) occurring during the vibratory stress relief were examined. Compared with the effects corresponding to the same alloy under non-vibration condition, it can be observed that the uniform surface residual stress distribution and relaxation of the compressive residual stress in the stress concentration zone were observed rather than all of the residual stresses being eliminated. Furthermore, with an increase in the vibrational aging time, the compressive residual stress, texture density, and (0002) preferred orientation increased first and then decreased. It should be underlined that the vibratory stress relief process for the vibrational aging time of more than 10 min is able to weaken the strong basal textures of AZ31 Mg alloys, which is valuable for enhancement of their formability and is responsible for an almost perfect 3D-Debye–Scherrer ring. - Highlights: • 3D-Debye ring about VSR technique is not discussed in the existing literature. • A newly developed VSR method is suitable for small or thin workpieces. • The cosα method accurately and effectively determines the residual stresses. • The VSR technique is valuable for enhancement of their formability. • The texture and preferred orientation change with the vibrational aging time.

  7. The relationships between residual stress relaxation and texture development in AZ31 Mg alloys via the vibratory stress relief technique

    International Nuclear Information System (INIS)

    A systematic study of residual stress relaxation and the texture evolution of cold-rolled AZ31 Mg alloys using the vibratory stress relief technique with a simple cantilever beam vibration system was performed using a high-resolution X-ray diffractometer and a portable X-ray residual stress analyzer. The effects of vibrational stress excitation on the surface residual stress distribution and on the texture of pole figures (0002) occurring during the vibratory stress relief were examined. Compared with the effects corresponding to the same alloy under non-vibration condition, it can be observed that the uniform surface residual stress distribution and relaxation of the compressive residual stress in the stress concentration zone were observed rather than all of the residual stresses being eliminated. Furthermore, with an increase in the vibrational aging time, the compressive residual stress, texture density, and (0002) preferred orientation increased first and then decreased. It should be underlined that the vibratory stress relief process for the vibrational aging time of more than 10 min is able to weaken the strong basal textures of AZ31 Mg alloys, which is valuable for enhancement of their formability and is responsible for an almost perfect 3D-Debye–Scherrer ring. - Highlights: • 3D-Debye ring about VSR technique is not discussed in the existing literature. • A newly developed VSR method is suitable for small or thin workpieces. • The cosα method accurately and effectively determines the residual stresses. • The VSR technique is valuable for enhancement of their formability. • The texture and preferred orientation change with the vibrational aging time

  8. Relationship between grain size and Zener-Holloman parameter during friction stir processing in AZ31 Mg alloys

    International Nuclear Information System (INIS)

    The relationship between the resulting grain size and the applied working strain rate and temperature for the friction stir processing in AZ31 Mg is systemically examined. The Zener-Holloman parameter is utilized in rationalizing the relationship. The grain orientation distribution is also studied using the X-ray diffraction

  9. Laser-tungsten inert gas hybrid welding of dissimilar metals AZ31B Mg alloys to Zn coated steel

    International Nuclear Information System (INIS)

    Highlights: ► Successful joining Mg to Zn coated steel using laser-TIG hybrid welding. ► Metallurgical bonding was achieved at the Mg/Zn coated steel interface. ► Influence of laser power on joining Mg to Zn coated steel was investigated. ► Newly formed Fe3Al phase improved the interfacial bonding and joint strength. ► The role of Zn coating in joining Mg to steel was clarified. - Abstract: Laser-tungsten inert gas (TIG) hybrid welding has been developed for joining Mg alloys to Zn coated steel in a lap joint configuration. The joint could not be produced in laser or arc welding only, while acceptable joints without obvious defects were obtained with a relatively wide processing window in the hybrid process. Two reaction layers were observed to form at the interface and were identified as Mg–Zn eutectic structure (α-Mg + MgZn) and Fe3Al phase by TEM analysis. In some cases, Al6Mn phase also formed adjacent to the Fe–Al reaction layer. The tensile-shear strength attained the maximum value of 68 MPa, representing 52.3% joint efficiency relative to Mg base metal. The element Al from AZ31B Mg alloys diffused to the liquid/solid interface and then reacted with the elements from steel, such as Fe and Mn, contributing to the metallurgical bonding at the interface. The weak bonding between Mg–Zn reaction layer and newly formed Fe–Al layer resulted in the interfacial failure

  10. AZ31镁合金搅拌摩擦点焊%Friction stir spot welding of AZ31 Mg-alloy

    Institute of Scientific and Technical Information of China (English)

    尹玉环; 胡绳荪; North T.H.; 张晓博; 孙娜

    2011-01-01

    研究了搅拌头旋转频率以及停留时间对AZ31镁合金搅拌摩擦点焊接头力学性能的影响.随着旋转频率的增大,不同搅拌针条件下,AZ31搅拌摩擦点焊接头的力学性能均呈现先增大后减小的趋势.随着停留时间的延长,AZ31搅拌摩擦点焊接头的力学性能先增大随后在一定范围内波动.结果表明,结合宽度是影响搅拌摩擦点焊接头力学性能的重要因素,结合宽度越大,点焊接头的力学性能越好;此外,上下板之间界面特征对搅拌摩擦点焊接头的力学性能也具有重要的影响.

  11. Influence of texture on the recrystallization mechanisms in an AZ31 Mg sheet alloy at dynamic rates

    OpenAIRE

    Dudamell, N.V.; Ulacia, I.; Galvez Diaz-Rubio, Francisco; Yi, S.; Bohlen, J.; Letzig, D.; Hurtado, I.; Pérez Prado, María Teresa

    2012-01-01

    An AZ31 rolled sheet alloy has been tested at dynamic strain rates View the MathML source at 250 °C up to various intermediate strains before failure in order to investigate the predominant deformation and restoration mechanisms. In particular, tests have been carried out in compression along the rolling direction (RD), in tension along the RD and in compression along the normal direction (ND). It has been found that dynamic recrystallization (DRX) takes place despite the limited diffusion ta...

  12. Long-term corrosion inhibition mechanism of microarc oxidation coated AZ31 Mg alloys for biomedical applications

    International Nuclear Information System (INIS)

    Highlights: ► The corrosion behavior is significantly affected by the long-term immersion. ► The degradation is inhibited due to the corrosion product layer. ► The corrosion resistance is enhanced by optimized MAO electrolyte concentrations. ► The corrosion inhibition mechanism is presented by a Flash animation. - Abstract: This paper addresses the long-term corrosion behavior of microarc oxidation coated Mg alloys immersed in simulated body fluid for 28 days. The coatings on AZ31 Mg alloys were produced in the electrolyte of sodium phosphate (Na3PO4) at the concentration of 20 g/L, 30 g/L and 40 g/L, respectively. Scanning electron microscope (SEM) and optical micrograph were used to observe the microstructure of the samples before and after corrosion. The composition of the MAO coating and corrosion products were determined by X-Ray Diffraction (XRD). Corrosion product identification showed that hydroxyapatite (HA) was formed on the surface of the corroded samples. The ratio of Ca/P in HA determined by the X-ray Fluorescence (XRF) technique showed that HA is an acceptable biocompatible implant material. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to characterize the corrosion rate and the electrochemical impedance. The corrosion resistance of the coated Mg alloys can be enhanced by optimizing the electrolyte concentrations for fabricating samples, and is enhanced after immersing the coated samples in simulated body fluid for more than 14 days. The enhanced corrosion resistance after long-term immersion is attributed to a corrosion product layer formed on the sample surface. The inhibition mechanism of the corrosion process is discussed and presented with an animation

  13. The Influence of Various Additives on the Properties of Peo Coatings Formed on AZ31 mg Alloy

    Science.gov (United States)

    Rehman, Zeeshan Ur; Ahn, Byung-Hyun; Jeong, Yeong Seung; Song, Jung-Il; Koo, Bon-Heun

    2016-03-01

    In this work, plasma electrolytic oxidation (PEO) ceramic coatings were prepared on magnesium AZ31B alloy. Various electrolyte solutions including phosphate, aluminate and silicate as additives and NaOH + Na2SiF6 as constant agent were used to prepare the coatings. Influence of the additives on chemical composition and structure of the PEO coatings were examined by means of scanning electron microscope (SEM) and XRD. From structural analysis it was found that coatings prepared in the aluminate-based electrolyte have the best structural features. Microhardness and tribological characteristics of the PEO coatings were investigated using Vickers hardness test and pin-on-disc test. Microhardness for aluminate-based coating was found to be 1169.63HV while those for silicate-and phosphate-based coatings were 1093.42HV and 285.91HV, respectively. Wear rate of the aluminate-based coating was found to be lowest than all other coatings having a value of 2.78×10‑3mg/Nm.

  14. Preparation and Characterization of Hydroxyapatite Coating on AZ31 Mg Alloy for Implant Applications

    OpenAIRE

    Salman, S. A.; Kuroda, K.; Okido, M.

    2013-01-01

    Magnesium alloys as biodegradable metal implants in orthopaedic research received a lot of interest in recent years. They have attractive biological properties including being essential to human metabolism, biocompatibility, and biodegradability. However, magnesium can corrode too rapidly in the high-chloride environment of the physiological system, loosing mechanical integrity before the tissue has sufficiently healed. Hydroxyapatite (HAp) coating was proposed to decrease the corrosion rate ...

  15. Enhancing Microstructure and Mechanical Properties of AZ31-MWCNT Nanocomposites through Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    J. Jayakumar

    2013-01-01

    Full Text Available Multiwall carbon nanotubes (MWCNTs reinforced Mg alloy AZ31 nanocomposites were fabricated by mechanical alloying and powder metallurgy technique. The reinforcement material MWCNTs were blended in three weight fractions (0.33%, 0.66%, and 1% with the matrix material AZ31 (Al-3%, zinc-1% rest Mg and blended through mechanical alloying using a high energy planetary ball mill. Specimens of monolithic AZ31 and AZ31-MWCNT composites were fabricated through powder metallurgy technique. The microstructure, density, hardness, porosity, ductility, and tensile properties of monolithic AZ31 and AZ31-MWCNT nano composites were characterized and compared. The characterization reveals significant reduction in CNT (carbon nanoTube agglomeration and enhancement in microstructure and mechanical properties due to mechanical alloying through ball milling.

  16. Effect of Sr addition on texture evolution of Mg-3Al-1Zn (AZ31) alloy during extrusion

    International Nuclear Information System (INIS)

    Research highlights: → Hot compression tests were conducted on AZ31(0-1)Sr alloys at different temperatures. → Micro-mechanisms were divided into 4 sections (high and low T, high and low Sr). → A general micro mechanism map has been plotted based on the texture result. → The map is divided into two bulging and PSN regions and a mixed region in between. → The extremes of the two regions are limited by surface cracking and twining. - Abstract: An experimental investigation of texture evolution during the elevated temperature extrusion of AZ31 alloys containing strontium (Sr) additions is reported. The crystallographic texture of hot extruded alloys containing different levels of Sr has been examined. Hot compression tests have been carried out in order to investigate the hot deformation behavior of the as-cast alloys. It was seen that, at different extrusion temperatures and levels of Sr, different dynamic recrystallization (DRX) mechanisms become dominant which affect the final texture. At lower temperatures and at low levels of Sr, the bulging of grain boundaries was activated, resulting in a necklaced grain structure. Furthermore, a strong deformation texture of parallel to extrusion direction was developed as a result of bulging at the grain boundaries. Twining which was activated in the early stages of deformation, acted as nucleation sites for DRX. In contrast, at high temperatures and high levels of Sr, particle stimulated nucleation (PSN) becomes significant resulting in the weakening of the overall texture with the recrystallization of new grains of random orientation. In order to prevent the surface cracking in the extruded sample, a limit for Sr concentration and deformation temperature was determined. A shoulder region was found in between the bulging and PSN-dominant areas where both mechanisms are active.

  17. Microstructure and mechanical properties of extruded and ECAPed AZ31 Mg alloy, grain refined with Al-Ti-C master alloy

    International Nuclear Information System (INIS)

    Different amounts of Al-3Ti-0.15C master alloy (TiCAl), as grain refiner, were added to the AZ31 magnesium alloy (Mg-3Al-1Zn-0.3Mn) and the resulting microstructure, grain size distributions, texture, and mechanical properties were studied after extrusion and equal channel angular pressing (ECAP). Results showed that the addition of 1.0 wt.% TiCAl had the strongest grain refinement effect, reducing the grain sizes by 51.2 and 38.4% in the extruded and ECAPed conditions, respectively. The observed grain refinement was in part due to the presence of the thermally stable micron- and submicron-sized particles in the melt which act as nucleation sites during solidification. During the high-temperature extrusion and ECAP processes, dynamic recrystallization (DRX) and grain growth are likely to occur. However, second phase particles will help in reducing the grain size by the particle stimulated nucleation (PSN) mechanism. Furthermore, the pinning effect of these particles can oppose grain growth by reducing the grain boundary migration. These two phenomena together with the partitioning of the grains imposed by the severe plastic deformation in the ECAP process have all contributed to the achieved fine-grained structure in the AZ31 alloy with enhanced mechanical properties. The enhancement in the shear yield stress (SYS) and ultimate shear strengths (USS) were, respectively, 11.2 and 6.1% in the extruded state, and 7.6 and 3.9% in the ECAPed conditions. The weaker strengthening effect of grain refinement in the ECAPed alloys can be attributed to the textural modifications which partly offset the achieved grain boundary strengthening.

  18. Effect of welding current on strength and microstructure in resistance spot welding of AZ31 Mg alloy

    Institute of Scientific and Technical Information of China (English)

    Wang Yarong; Zhang Zhongdian; Feng Jicai

    2007-01-01

    In this paper, resistance spot welding were performed on 1mm-thickness magnesium AZ31B plates. The effect of welding current on the microstructure and tensile shear force was investigated. It was found that the welding current governed the nugget growth, and the nugget could not form if current levels were insufficient. The nugget revealed a homogeneous, equiaxed, fine-grained structure, which consisted of non-equilibrium microstructure of α-phase dendrites surrounded by eutectic mixtures of α and β (Mg17Al12) in the grain boundaries. With increasing welding current, the size of grains in nugget would be more smaller and uniform, and the width of plastic rings would be larger. Tensile shear tests showed that tensile shear force of the joints increased with increasing welding current when the welding current was smaller than 17 000 A.The maximum tensile shear force was up to 1980 N.

  19. Effect of ultrasonic cold forging technology as the pretreatment on the corrosion resistance of MAO Ca/P coating on AZ31B Mg alloy

    International Nuclear Information System (INIS)

    Highlights: • Ultrasonic cold forging technology was used as the pretreatment for MAO coating. • Nano layer with the grain size of 30–80 nm was formed on the UCFT treated surface. • Calcium phosphate contained coating was obtained by MAO process. • The remained nano layer underlying MAO coating could impact the corrosion resistance greatly. - Abstract: A calcium phosphate contained (Ca/P) coating was obtained on AZ31B Mg alloy by micro-arc oxidation (MAO) process under the pretreatment of ultrasonic cold forging technology (UCFT). The surface nanograins were introduced after UCFT pretreatment on AZ31B Mg alloy. Optical microscope (OM) was employed to observe the microstructures of the untreated and UCFT treated samples. Transmission electron microscopy (TEM) and atomic force microscope (AFM) were employed to observe the microstructures of nanograins and the surface roughness of the UCFT treated Mg alloys. The grain size of the UCFT treated Mg alloy is 48.67 nm and the surface roughness is 17.03 nm. The microstructures and the phase compositions of MAO samples were observed and analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD results show that the coating include Ca/P phase, including hydroxyapatite (Ca10(PO4)6(OH)2), HA), tertiary calcium phosphate (Ca3(PO4)2, TCP) and calcium phosphate dehydrate (CaHPO4⋅2H2O, DCPD). The hardness of the samples was measured by the micro-hardness tester under the loads of 10 g, 25 g and 50 g. 3D topographies of hardness indenter were characterized by 3D profiler. The immersion tests and potentiodynamic polarization tests were used to evaluate the weight loss rate and corrosion current density in simulated body fluid (SBF). The results show that the corrosion resistance of Ca/P MAO coating on Mg alloy was improved greatly by the pretreatment of UCFT

  20. On the deformation twinning of Mg AZ31B

    DEFF Research Database (Denmark)

    Abdolvand, Hamidreza; Majkut, Marta; Oddershede, Jette;

    2015-01-01

    Crystals with a hexagonal close-packed (HCP) structure are inherently anisotropic, and have a limited number of independent slip systems, which leads to strong deformation textures and reduced formability in polycrystalline products. Tension along the c-axis of the crystal ideally activates...... extension twinning as a deformation mode due to the lack of easy-slip systems. In this work, experiments were devised to study extension twinning in a polycrystalline Mg alloy AZ31B with a strong basal rolling texture by tensile deformation parallel to the plate normal. Three-dimensional synchrotron X...

  1. Mechanical Behavior of AZ31B Mg Alloy Sheets under Monotonic and Cyclic Loadings at Room and Moderately Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Ngoc-Trung Nguyen

    2014-02-01

    Full Text Available Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension at and slightly above room temperature were recorded. Strong yielding asymmetry and nonlinear hardening behavior were also revealed. Considerable Bauschinger effects, transient behavior, and variable permanent softening responses were observed near room temperature, but these were reduced and almost disappeared as the temperature increased. Different stress–strain responses were inherent to the activation of twinning at lower temperatures and non-basal slip systems at elevated temperatures. A critical temperature was identified to account for the transition between the twinning-dominant and slip-dominant deformation mechanisms. Accordingly, below the transition point, stress–strain curves of cyclic loading tests exhibited concave-up shapes for compression or compression following tension, and an unusual S-shape for tension following compression. This unusual shape disappeared when the temperature was above the transition point. Shrinkage of the elastic range and variation in Young’s modulus due to plastic strain deformation during stress reversals were also observed. The texture-induced anisotropy of both the elastic and plastic behaviors was characterized experimentally.

  2. Fatigue behavior of friction stir spot welded AZ31 Mg alloy sheet joints%AZ31镁合金板材搅拌摩擦点焊连接件的疲劳行为

    Institute of Scientific and Technical Information of China (English)

    罗天骄; 史宝良; 段启强; 付俊伟; 杨院生

    2013-01-01

      利用拉压疲劳实验研究 AZ31板材搅拌摩擦点焊连接件的疲劳行为。结果表明:AZ31镁合金板材搅拌摩擦点焊连接件的疲劳失效均发生在搅拌区,疲劳裂纹均起源于搅拌区外侧边缘,位于上下板之间。当循环加载等于1 kN 时,疲劳裂纹沿着热影响区和热机械区界面且垂直载荷的方向扩展;而当循环载荷等于3 kN时,疲劳裂纹则沿着搅拌区直径方向扩展,并最终发生剪切断裂。另外,断口横截面显微分析显示,在AZ31板间搅拌区外侧存在一个“舌状区”,“舌状区”的方向是沿搅拌区向外,疲劳裂纹均起源于“舌状区”。%The fatigue behavior of friction stir spot welded (FSSW) AZ31 magnesium alloy sheet joints was investigated by tension−compression of fatigue test. The results suggest that all the fatigue failures occur at the stir zone of the FSSW AZ31 sheet joints, and all cracks initiate at the stir zone outer edge between the upper and lower sheet. When the cycle force equals 1 kN, the crack propagates along the interface of heat-affected zone and thermo-mechanical zone, simultaneously across the direction of force;while the cycle force equals 3 kN, the crack propagates along the diameter of stir zone and shear failure occurs finally. Moreover, the transverse microsections indicate that there is a tongue-like region at the outer edge of stir zone between the two AZ31 sheets, and the direction of tongue-like region is toward outside of the stirred zone and all fatigue cracks initiate at the tongue-like region.

  3. Friction stir keyholeless spot welding of AZ31 Mg alloy-mild steel%镁钢无匙孔搅拌摩擦点焊

    Institute of Scientific and Technical Information of China (English)

    张忠科; 王希靖; 王培中; 赵刚

    2014-01-01

    Friction stir keyholeless spot welding (FSKSW) using a retractable pin for 1.0 mm thick galvanized mild steel and 3 mm thick AZ31B magnesium alloy in a lap configuration was investigated. The process variables were optimized in terms of the joint strength. The effects of the stacking sequence on joint formation and the joining mechanism of FSKSW AZ31B-to-mild steel joints were also analyzed. It shows that the process window and joint strength are strongly influenced by the stacking sequence of the workpieces. While the process window is narrow and unstable for FSKSW of a magnesium-to-steel stack-up, a desirable process was established for the steel-to-magnesium stacking sequence, a desirable process and higher strength joint can be got when the steel-to-magnesium stacking sequence. XRD phase and EPMA analyses of the FSKSW joint showed that the intermetallic compounds are formed at the steel-to-magnesium interface, and the element diffusion between the mild steel and AZ31B magnesium alloy revealed that the joining methods for FSKSW joints is the main mechanical joining along with certain metallurgical bonding.%采用可回抽针的搅拌摩擦点焊装置,对1 mm厚镀锌钢板和3 mm厚AZ31镁合金板进行搅拌摩擦点焊。利用正交优化法以剪切力作为评价指标进行工艺优化,研究搭叠位置的影响及无匙孔搅拌摩擦点焊的连接机理。结果表明:搭叠方式对接头力学性能有很大影响,钢上镁下方式大大优于镁上钢下方式。XRD和EPMA线扫描分析发现在镁钢接头形成Fe3Al 和 MgFeAlO4等金属间化合物,同时存一定的扩散行为,接头连接方式主要是以机械结合为主,同时存在冶金结合。

  4. Characterization of AZ31 magnesium alloy by duplex process combining laser surface melting and plasma electrolytic oxidation

    Science.gov (United States)

    Liu, Cancan; Liang, Jun; Zhou, Jiansong; Li, Qingbiao; Wang, Lingqian

    2016-09-01

    Top ceramic coatings were fabricated on the laser surface melting (LSM) modified AZ31 alloy by plasma electrolytic oxidation (PEO) in a phosphate electrolyte. The effect of LSM treatment on the microstructure and corrosion behavior of the bare and PEO treated AZ31 alloy was evaluated. Results showed that LSM treatment produced a homogeneous modified layer with redistributed intermetallic compounds, resulting in enhanced corrosion resistance of AZ31 alloy. The LSM treatment had no obvious influence on the surface and cross-sectional microstructures of the PEO coatings on AZ31 alloy. Besides, MgO was the main constituent for PEO coatings, regardless of LSM pretreatment. However, the long-term corrosion properties of the PEO coated AZ31 alloy with LSM pretreatment revealed large enhancement. Based on the analysis of microstructure and corrosion property, the corrosion mechanisms of the PEO and LSM-PEO coated AZ31 alloy were proposed.

  5. Corrosion resistance of biodegradable polymeric layer-by-layer coatings on magnesium alloy AZ31

    Science.gov (United States)

    Cui, Lan-Yue; Zeng, Rong-Chang; Zhu, Xiao-Xiao; Pang, Ting-Ting; Li, Shuo-Qi; Zhang, Fen

    2016-06-01

    Biocompatible polyelectrolyte multilayers (PEMs) and polysiloxane hybrid coatings were prepared to improve the corrosion resistance of biodegradable Mg alloy AZ31. The PEMs, which contained alternating poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were first self-assembled on the surface of the AZ31 alloy substrate via electrostatic interactions, designated as (PAH/PSS)5/AZ31. Then, the (PAH/PSS)5/AZ31 samples were dipped into a methyltrimethoxysilane (MTMS) solution to fabricate the PMTMS films, designated as PMTMS/(PAH/PSS)5/AZ31. The surface morphologies, microstructures and chemical compositions of the films were investigated by FE-SEM, FTIR, XRD and XPS. Potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution measurements demonstrated that the PMTMS/(PAH/PSS)5/AZ31 composite film significantly enhanced the corrosion resistance of the AZ31 alloy in Hank's balanced salt solution (HBSS). The PAH and PSS films effectively improved the deposition of Ca-P compounds including Ca3(PO4)2 and hydroxyapatite (HA). Moreover, the corrosion mechanism of the composite coating was discussed. These coatings could be an alternative candidate coating for biodegradable Mg alloys.

  6. Design and assessment of a wrapped cylindrical Ca-P AZ31 Mg alloy for critical-size ulna defect repair.

    Science.gov (United States)

    Smith, Montserrat Rabago; Atkinson, Patrick; White, Désirée; Piersma, Tyler; Gutierrez, Gloria; Rossini, Gianny; Desai, Sapna; Wellinghoff, Stephen; Yu, Hui; Cheng, Xingguo

    2012-01-01

    Recently, magnesium has been investigated as a promising bioresorbable orthopedic biomaterial. Its mechanical properties are very similar to natural bone, making it appropriate for load-bearing orthopedic fracture repair applications. However, significant hurdles remain regarding the design of practical implants and methods to control degradation and enhance biocompatibility. Although attempts have been made to hinder magnesium's rapid corrosion via alloying and coating, these studies have used solid monoliths. In an effort to reduce the amount of alloy used for implantation in a shape that mimics cortical bone shape, this study used a thin sheet of Mg AZ31 which was rolled into hollow cylindrical scaffolds. The scaffold was coated with different amounts of Ca-P; this implant demonstrated slowed corrosion in simulated body fluid (SBF) as well as enhanced biocompatibility for mesenchymal stem cells (MSC). In vivo implantation of magnesium alloy scaffold adjacent to the rat femur showed significant biointegration with further deposition of complex Mg-Ca phosphates/carbonates typical of natural bone. Finally, the implant was placed in a critical-size ulna defect in live rabbits, which lead to radiographic union and partial restoration of biomechanical strength in the defect. This study demonstrated that a thin sheet of coated Mg alloy that was spirally wrapped wound be a promising orthopedic biomaterial for bone repair. PMID:22102519

  7. Effect of ultrasonic cold forging technology as the pretreatment on the corrosion resistance of MAO Ca/P coating on AZ31B Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lingling, E-mail: daisy_chenlingling@163.com [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Gu, Yanhong, E-mail: gu_yanhong@163.com [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Liu, Lu, E-mail: liulu@bipt.edu.cn [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Liu, Shujing, E-mail: liushujing@bipt.edu.cn [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Hou, Binbin, E-mail: sohu19880815@126.com [School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China); Liu, Qi, E-mail: 13521196884@sina.cn [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China); Ding, Haiyang, E-mail: dinghaiyang@bipt.edu.cn [College of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 (China)

    2015-06-25

    Highlights: • Ultrasonic cold forging technology was used as the pretreatment for MAO coating. • Nano layer with the grain size of 30–80 nm was formed on the UCFT treated surface. • Calcium phosphate contained coating was obtained by MAO process. • The remained nano layer underlying MAO coating could impact the corrosion resistance greatly. - Abstract: A calcium phosphate contained (Ca/P) coating was obtained on AZ31B Mg alloy by micro-arc oxidation (MAO) process under the pretreatment of ultrasonic cold forging technology (UCFT). The surface nanograins were introduced after UCFT pretreatment on AZ31B Mg alloy. Optical microscope (OM) was employed to observe the microstructures of the untreated and UCFT treated samples. Transmission electron microscopy (TEM) and atomic force microscope (AFM) were employed to observe the microstructures of nanograins and the surface roughness of the UCFT treated Mg alloys. The grain size of the UCFT treated Mg alloy is 48.67 nm and the surface roughness is 17.03 nm. The microstructures and the phase compositions of MAO samples were observed and analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The XRD results show that the coating include Ca/P phase, including hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}), HA), tertiary calcium phosphate (Ca{sub 3}(PO{sub 4}){sub 2}, TCP) and calcium phosphate dehydrate (CaHPO{sub 4}⋅2H{sub 2}O, DCPD). The hardness of the samples was measured by the micro-hardness tester under the loads of 10 g, 25 g and 50 g. 3D topographies of hardness indenter were characterized by 3D profiler. The immersion tests and potentiodynamic polarization tests were used to evaluate the weight loss rate and corrosion current density in simulated body fluid (SBF). The results show that the corrosion resistance of Ca/P MAO coating on Mg alloy was improved greatly by the pretreatment of UCFT.

  8. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    Science.gov (United States)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  9. Corrosion resistance of AZ31 alloy after plastic working in NaCl solutions

    Directory of Open Access Journals (Sweden)

    W. Walke

    2011-04-01

    Full Text Available Purpose: The purpose of the study was to assess corrosion resistance of magnesium alloy AZ31 (Mg-Al-Zn alloy after plastic working in NaCl solutions. It presents currently applied methods of magnesium alloys plastic working. Basic groups of magnesium alloys that are used for plastic working have been discussed.Design/methodology/approach: Corrosion tests of AZ31 alloy were carried out in solution with concentration of 0.01-2 M NaCl with application of the system for electrochemical tests VoltaLab®PGP201. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method. Immersion tests were carried out in NaCl solutions in the time of 1-5 days. Scanning microscopy enabled to present microstructure of AZ31 after immersion tests.Findings: Results of all carried out tests explicitly prove deterioration of corrosion properties of magnesium alloy AZ31 with the increase in molar concentration of NaCl solution.Practical implications: It was determined that irrespective of molar concentration of NaCl solution pitting corrosion was found in the tested alloy. It proves that application of protective coating on elements made of the tested alloy is necessary.Originality/value: Literature gives the results of corrosion tests with reference to cast alloy AZ31. Tests of corrosion resistance of hot rolled AZ31 in chloride solutions have been made for the first time.

  10. A MANGANESE OXIDE CONTAINED COATING FOR BIODEGRADABLE AZ31B MAGNESIUM ALLOY

    OpenAIRE

    TINGTING YAN; LILI TAN; DANGSHENG XIONG; BINGCHUN ZHANG; KE YANG

    2009-01-01

    A manganese oxide contained coating was prepared on biodegradable AZ31B magnesium alloy to control the degradation of AZ31B and improve its biocompatibility. Morphology, composition, and corrosion resistance of the coating were studied. The SEM observations showed that the coating was approximately 4–6 μm in thickness with net-like microcracks. The XPS analysis indicated that the coating was mainly composed of MgO, Mg(OH)2, MnO2, Mn2O3, and Mn3O4. It was found that AZ31B with such coating sho...

  11. Hot Deformation Kinetics of Magnesium Alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; HUANG Guangjie; FAN Yonge; LU Zhiwen; PAN Fusheng

    2006-01-01

    The flow stress at elevated temperatures for magnesium alloy AZ31 was studied using isothermal compression testing. The effect of deformation parameters on the flow stress was studied as well. The kinetics of elevated temperature deformation was expressed by means of some empirical rate equations. The activation parameter has been calculated. A mechanism for the dynamic softening of AZ31 alloy in a hot deformation experiment was identified to be the dynamic recrystallization.

  12. Microstructure and corrosion resistance of Ce–V conversion coating on AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: • Through simple chemical conversion process, a Ce–V conversion coating is prepared on AZ31 magnesium alloy. The coating (∼2 μm thick) has a duplex structure and is composed of Mg, Al, Ce, V and O in the outer layer and Mg, Al, V, F and O in the inner layer. • The Ce–V conversion coating can increase the Ecorr by 157 mV and decrease the icorr by 80 times compared to AZ31 magnesium alloy substrate. Moreover, the performance of the Ce–V conversion coating excels the chromate conversion coating on AZ31 magnesium alloy. • The EIS results of Ce–V conversion coating indicate an increase of 10× in the corrosion resistance and a delay in the corrosion process kinetics compared to uncoated AZ31 magnesium alloy in 3.5 wt.% NaCl solution. • The ball cratering is a simple and effective technique of thickness measurement for chemical conversion coating. - Abstract: A Ce–V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 μm. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce–V conversion coating can provide effective protection to AZ31 magnesium alloy

  13. Carbon Nanotube Addition to Simultaneously Enhance Strength and Ductility of Hybrid AZ31/AA5083 Alloy

    OpenAIRE

    Muralidharan Paramsothy; Manoj Gupta; Jimmy Chan; Richard Kwok

    2011-01-01

    AZ31/AA5083 hybrid alloy nanocomposite containing CNT nanoparticle reinforcement was fabricated using solidification processing followed by hot extrusion. The AZ31/AA5083 hybrid alloy nanocomposite exhibited similar grain size to monolithic AZ31/AA5083 hybrid alloy, reasonable CNT nanoparticle distribution, non-dominant (0 0 0 2) texture in the longitudinal direction, and 20% higher hardness than monolithic AZ31/AA5083 hybrid alloy. Compared to monolithic AZ31/AA5083 hybrid alloy (in tension)...

  14. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yufu, E-mail: Yufu.Ren@rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Nabiyouni, Maryam [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10 min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7 days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5 days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. - Highlights: • A microwave assisted coating process for biodegradable Mg alloy. • CDHA coatings were successfully developed on AZ31 alloy in minutes. • The as-deposited CDHA coatings significantly reduced the degradation rate of AZ31 alloy. • The CDHA coated AZ31 alloy showed good bioactivity and biocompatibility in vitro. • The microwave assisted coating process can be used as rapid surface modification for bioimplants.

  15. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy

    International Nuclear Information System (INIS)

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10 min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7 days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5 days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. - Highlights: • A microwave assisted coating process for biodegradable Mg alloy. • CDHA coatings were successfully developed on AZ31 alloy in minutes. • The as-deposited CDHA coatings significantly reduced the degradation rate of AZ31 alloy. • The CDHA coated AZ31 alloy showed good bioactivity and biocompatibility in vitro. • The microwave assisted coating process can be used as rapid surface modification for bioimplants

  16. Preliminary study of biodegradation of AZ31B magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    REN Yibin; HUANG Jingjing; ZHANG Bingchun; YANG Ke

    2007-01-01

    Magnesium alloys are potential to be developed as a new type of biodegradable implant material by use of their active corrosion behavior.Both in vitro and in vivo biodegradation properties of an AZ31B magnesium alloy were investigated in this work.The results showed that AZ31B alloy has a proper degradation rate and much lower hydrogen release in Hank's solution,with a degradation rate of about 0.3 mm/year and hydrogen release below 0.15mL/cm2.The animal implantation test showed that the AZ31B alloy could slowly biodegrade in femur of the rabbit and form calcium phosphate around the alloy sample,with the Ca/P ratio close to the natural bone.

  17. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    Science.gov (United States)

    Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.

    2015-12-01

    ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.

  18. Three-dimensional investigation of grain boundary–twin interactions in a Mg AZ31 alloy by electron backscatter diffraction and continuum modeling

    International Nuclear Information System (INIS)

    The effect of grain boundary (GB) misorientation (θ) on twinning in a Mg AZ31 alloy is investigated using a three-dimensional (3-D) experimental and modeling approach, in which 3-D electron backscattered diffraction is performed in a volume consisting of a central grain, favorably oriented for twinning, and surrounded by three boundaries, with θ ranging from 15° to 64°. This study corroborates previous observations that twin nucleation and propagation are favored at low θ. Furthermore, it reveals that non-Schmid effects, such as the activation of low Schmid factor (SF) variants or of double tensile twins, are absent in the vicinity of low misorientation boundaries and that they become more abundant as θ increases. The 3-D morphology of individual twin variants is found to be related to their SF. High SF variants have well-established plate morphology, while low SF variants adopt irregular shapes. A crystal plasticity continuum model recently proposed by the authors is used in a very high intragrain resolution and large-scale finite element polycrystalline aggregate model of the experimental specimen. This model is shown to successfully capture the influence of θ on twin propagation and variant selection. It ultimately predicts (i) a rise in local non-basal slip with increasing θ, (ii) that low θ GB favor twin nucleation by non-Schmid stress concentrations, but that propagation is immediately accommodated by the macroscopic stress, and (iii) that high θ GB are not favorable twin nucleation sites, despite having high von Mises stress concentrations

  19. Grain refinement of AZ31 magnesium alloy by electromagnetic stirring under effect of grain-refiner

    Indian Academy of Sciences (India)

    S Y Gao; Q C Le; Z Q Zhang; J Z Cui

    2012-08-01

    The effects of electromagnetic stirring and Al4C3 grain refiner on the grain refinement of semicontinuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has an effective refining effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3 grain refiner. Electromagnetic stirring can `activate’ the Al4C3 particles, resulting in more heterogeneous nucleation sites for the primary -Mg grains. But, longer holding time can `deactivate’ the Al4C3 particles and poison the grain refining effect.

  20. The Formablity of AZ31B Magnesium Alloy Sheet

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; LU Zhiwen; ZHAO Yazhong; QIU Xiaogang

    2006-01-01

    The forming limit diagrams(FLD)of AZ31B magnesium alloy sheet were tested by means of the electro etching grid method based on the forming experiment of magnesium alloy sheet carried out with a BCS-30D sheet forming testing machine and the strain testing analysis made with an advanced ASAME automatic strain measuring system. Experiments show that, at room temperature, the mechanical properties and deep drawing performance of AZ31B cold-rolled magnesium alloy sheet were so poor that it failed to test the forming limit diagrams without an ideal forming and processing capacity, while the hot-rolled magnesium alloy sheet was of a little better plasticity and forming performance after testing its forming limit diagrams. It can be concluded that the testing of the forming limit curves (FLC)offers the theoretical foundation for the drawing of the deep drawing and forming process of magnesium alloy sheet.

  1. Effect of partial rolling on the microstructure, mechanical properties and fracture behavior of AZ31 Mg alloy joints

    International Nuclear Information System (INIS)

    Partial rolling processes at different temperatures were conducted on the fusion zone (FZ) of double-side welded Mg–3Al–1Zn alloy joints with excess weld bead. The effect of rolling reduction and rolling temperature on the microstructure, mechanical properties and fracture behavior of the joints were investigated. Results show that both the strength and elongation of the joints increase significantly with rolling reduction owing to the microstructure evolution in the FZ. Once rolling reduction exceeds a critical value (CRR), tensile fracture location will be transferred from the FZ to the substrate and the joints can achieve tensile properties roughly the same as those of the initial substrate. Rolling at a lower temperature is preferred to obtaining a weak basal texture in the FZ, for the corresponding CRR is smaller

  2. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy.

    Science.gov (United States)

    Ren, Yufu; Zhou, Huan; Nabiyouni, Maryam; Bhaduri, Sarit B

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. PMID:25686961

  3. Nanomechanical analysis of AZ31 magnesium alloy and pure magnesium correlated with crystallographic orientation

    International Nuclear Information System (INIS)

    The anisotropic nanomechanical properties of AZ31 magnesium alloy and pure Mg were measured in situ via nanoindentation of individual grains with simultaneous observations using a scanning electron microscope. Values of the nanohardness, indentation size effect, elastic modulus, and yield strength were correlated with the crystallographic orientation provided by electron backscattering diffraction and were further used to investigate the relationships between the nanomechanical properties of the materials and the work of nanoindentation. The nanohardness of AZ31 was found to be generally above that of pure Mg due to solid solution strengthening. The nanohardness of AZ31 first considerably decreased and then marginally increased, whereas the nanohardness of pure Mg steadily decreased as the angle between the hexagonal lattice c-axis of both materials and the indentation direction increased. The indentation size effect was stronger for AZ31 than for pure Mg, and its magnitude decreased as the angle between the lattice c-axis and the indentation direction increased. The AZ31 modulus remained nearly constant throughout the range of investigated orientations; the modulus of pure Mg followed a theoretical angular dependence but was generally lower than expected. The yield strength behaved in a similar manner to the nanohardness in both materials. Plots of the ratio of the nanohardness to the yield strength revealed that both materials underwent significant work hardening shortly after nanoindentation began. It was also shown that the amount of plastic deformation increased for Mg and increased or remained nearly constant for AZ31 as the angle increased. The observed orientation dependencies were interpreted as a consequence of the anisotropic activities of the dominant slip systems and extension twinning

  4. Microstructural development of high temperature deformed AZ31 magnesium alloys

    International Nuclear Information System (INIS)

    Due to their significant role in automobile industries, high temperature deformation of Mg–Al–Zn alloys (AZ31) at constant stress (i.e. creep) were studied at a wide range of stresses and temperatures to characterize underlying deformation mechanism, dynamic recrystallization (DRX) and dislocation density evolution. Various microstructures (e.g. grain growth & DRX) are noted during steady-state creep mechanisms such as grain boundary sliding (GBS), dislocation glide creep (DGC) and dislocation climb creep (DCC). Although a combination of DRX and grain growth is characteristic of low stacking fault energy materials like Mg alloys at elevated temperatures, observation reveals grain growth at low strain-rates (GBS region) along with dynamic recovery (DRV) mechanism. X-Ray Diffraction (XRD) analysis revealed a decrease in dislocation density during GBS region while it increased under dislocation based creep mechanisms which could be related to the possible DRV and DRX respectively. Scanning Electron Microscopic (SEM) characterization of the fracture surface reveals more inter-granular fracture for large grains (i.e. GBS region with DRV process) and more dimple shape fracture for small grains (i.e. DGC & DCC region with DRX)

  5. Microstructural development of high temperature deformed AZ31 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shahbeigi Roodposhti, Peiman, E-mail: pshahbe@ncsu.edu; Sarkar, Apu; Murty, Korukonda Linga

    2015-02-25

    Due to their significant role in automobile industries, high temperature deformation of Mg–Al–Zn alloys (AZ31) at constant stress (i.e. creep) were studied at a wide range of stresses and temperatures to characterize underlying deformation mechanism, dynamic recrystallization (DRX) and dislocation density evolution. Various microstructures (e.g. grain growth & DRX) are noted during steady-state creep mechanisms such as grain boundary sliding (GBS), dislocation glide creep (DGC) and dislocation climb creep (DCC). Although a combination of DRX and grain growth is characteristic of low stacking fault energy materials like Mg alloys at elevated temperatures, observation reveals grain growth at low strain-rates (GBS region) along with dynamic recovery (DRV) mechanism. X-Ray Diffraction (XRD) analysis revealed a decrease in dislocation density during GBS region while it increased under dislocation based creep mechanisms which could be related to the possible DRV and DRX respectively. Scanning Electron Microscopic (SEM) characterization of the fracture surface reveals more inter-granular fracture for large grains (i.e. GBS region with DRV process) and more dimple shape fracture for small grains (i.e. DGC & DCC region with DRX)

  6. Inverter DC resistance spot welding of magnesium alloy AZ31

    OpenAIRE

    Hwang, I. S.; D. C. Kim; Kang, M. J.

    2011-01-01

    Purpose: The welding lobes of AC resistance spot welding and inverter DC resistance spot welding for the magnesium alloy sheet AZ31 were compared and analyzed.Design/methodology/approach: Using the welding lobe in terms of electrode force, weld time, and weld current which are process variables of the resistance spot welding, optimal welding conditions were determined. The lower limit of the range of the optimal welding condition was decided by minimum shear tension strength for the magnesium...

  7. The Role of Friction Stir Welding on the Microstructure and Mechanical Properties of AZ31B-H24 Mg alloy

    International Nuclear Information System (INIS)

    In this study, an attempt was made to join AZ31B magnesium alloy by friction stir welding (FSW) process. A single tool with cylindrical screw threaded pin was used to investigate the effect of welding parameters on microstructure and mechanical properties of stir zone (SZ). Several welds were made at different rotational (ω) and traverse (υ) speeds, while the ω/υ ratios were kept constant. The optical and scanning electron microscopy were used to study the variation of microstructure across the welds. Moreover, micro-hardness and tensile tests were carried out to evaluate the mechanical properties of joints. It was found that ω plays more significant role on the resulted grain structure than υ, and at a constant ω/υ ratio, decreasing rotational speed decreased the size of grains, and hence, improved the hardness value and the tensile strength of the SZ.

  8. Transition in Deformation Mechanism of AZ31 Magnesium Alloy during High-Temperature Tensile Deformation

    Directory of Open Access Journals (Sweden)

    Masafumi Noda

    2011-01-01

    Full Text Available Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31Mg alloy. At a test temperature of 523 K and an initial strain rate of 3×10−3 s-1, the AZ31Mg alloy (mean grain size: ~5 μm exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.

  9. Corrosion characterization of micro-arc oxidization composite electrophoretic coating on AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: • A new protective composite coatings were prepared on AZ31B Mg alloy. • The E-coat locked into MAO coat by discharge channels forming a smoother and compact surface without defects. • Comparing with MAO coat, the MAOE composite coat could provide an excellent barrier for bare Mg against corrosion attack. - Abstract: A two layer composite coating system was applied on the surface of AZ31B magnesium alloy by Micro-arc Oxidation (MAO) plus electrophoretic coat (E-coat) technique. The Mg sample coated with MAO plus E-coat (MAOE) was compared with bare Mg and Mg sample coated by MAO only. The surface microstructure and cross section of bare and coated Mg before and after corrosion were examined by Scanning Electron Microscopy (SEM). The corrosion performance of bare and coated Mg was evaluated using electrochemical measurement and hydrogen evolution test. The results indicated that the corrosion resistance of AZ31B Mg alloy was significantly improved by MAOE composite coating. The corrosion mechanism of bare and coated Mg is discussed

  10. Corrosion characterization of micro-arc oxidization composite electrophoretic coating on AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Congjie [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Jiang, Bailing [School of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816 (China); Liu, Ming [General Motors China Science Lab, Shanghai 201206 (China); Ge, Yanfeng [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China)

    2015-02-05

    Highlights: • A new protective composite coatings were prepared on AZ31B Mg alloy. • The E-coat locked into MAO coat by discharge channels forming a smoother and compact surface without defects. • Comparing with MAO coat, the MAOE composite coat could provide an excellent barrier for bare Mg against corrosion attack. - Abstract: A two layer composite coating system was applied on the surface of AZ31B magnesium alloy by Micro-arc Oxidation (MAO) plus electrophoretic coat (E-coat) technique. The Mg sample coated with MAO plus E-coat (MAOE) was compared with bare Mg and Mg sample coated by MAO only. The surface microstructure and cross section of bare and coated Mg before and after corrosion were examined by Scanning Electron Microscopy (SEM). The corrosion performance of bare and coated Mg was evaluated using electrochemical measurement and hydrogen evolution test. The results indicated that the corrosion resistance of AZ31B Mg alloy was significantly improved by MAOE composite coating. The corrosion mechanism of bare and coated Mg is discussed.

  11. Corrosion resistance of a composite polymeric coating applied on biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Zomorodian, A; Garcia, M P; Moura e Silva, T; Fernandes, J C S; Fernandes, M H; Montemor, M F

    2013-11-01

    The high corrosion rate of magnesium alloys is the main drawback to their widespread use, especially in biomedical applications. There is a need for developing new coatings that provide simultaneously corrosion resistance and enhanced biocompatibility. In this work, a composite coating containing polyether imide, with several diethylene triamine and hydroxyapatite contents, was applied on AZ31 magnesium alloys pre-treated with hydrofluoric acid by dip coating. The coated samples were immersed in Hank's solution and the coating performance was studied by electrochemical impedance spectroscopy and scanning electron microscopy. In addition, the behavior of MG63 osteoblastic cells on coated samples was investigated. The results confirmed that the new coatings not only slow down the corrosion rate of AZ31 magnesium alloys in Hank's solution, but also enhance the adhesion and proliferation of MG63 osteoblastic cells, especially when hydroxyapatite nanoparticles were introduced in the coating formulation. PMID:23454214

  12. Synthesis of dittmarite/Mg(OH)2 composite coating on AZ31 using hydrothermal treatment

    Science.gov (United States)

    Zhao, Qing; Mahmood, Waqas; Zhu, Yanying

    2016-03-01

    In this work, we have used hydrothermal method for the synthesis of dittmarite/Mg(OH)2 composite (DMC) layer on AZ31 alloy of magnesium. The synthesized coating was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). In a test immersion into the Hank's mixture for 31 days, the synthesized coating inhibited corrosion of AZ31 significantly and the amorphous calcium apatite precursor deposited on the coating surface. In another tape test, we noticed strong adhesion between the coating and substrate that eventually concludes that the synthesized coating is hydrophilic and a promising candidate to be used in the absorbable implant materials. Besides, the cytotoxicity of the AZ31 alloy with DMC coating, grown under different conditions on L-929 cells in vitro was examined indirectly through the growth inhibition method (MTT assay). The cytotoxicity of the deposited coating lie between 0 ∼ 1 that indicates it as a promising biomaterial.

  13. Effects of Sm on the grain refinement, microstructures and mechanical properties of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ming [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Hu, Xiaoyu [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Peng, Liming, E-mail: plm616@sjtu.edu.cn [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Fu, Penghuai [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Peng, Yinghong [School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2015-01-03

    The effects of samarium (Sm) on the grain refinement, microstructures and mechanical properties of as-cast AZ31 (Mg–3Al–1Zn–0.3Mn) magnesium (Mg) alloy have been investigated. Very serious grain coarsening happens when Sm content is between 0.16% and 1.18%. This is due to both the reactions between Al and Sm which reduce the constitutional undercooling effect and the lack of Al{sub 2}Sm heterogeneous nuclei. However, excellent grain refinement effect is achieved at Sm content above 2.17%, which is because the in-situ formed Al{sub 2}Sm particles significantly promote heterogeneous nucleation. The main phases in AZ31–xSm alloys include α-Mg, β-Mg{sub 17}Al{sub 12}, Al{sub 11}Sm{sub 3} and Al{sub 2}Sm. The Mg{sub 17}Al{sub 12} phase is gradually suppressed by the increase in Sm content, and the Al{sub 2}Sm is present at a higher Sm content. Because of grain refinement strengthening and secondary phase strengthening effects, the room temperature tensile property of AZ31–3.13Sm alloy has the optimal value of YS78.7MPa–UTS216.7MPa-EL13.6%.

  14. Superplastic Properties of AZ31 and AZ31-1.0Y-1.3Sr Alloy Produced by Twin-Roll Casting and Sequential Hot Rolling

    Science.gov (United States)

    Ning, Huiyan; Yu, Yandong; Lin, Kai; Wen, Lihua; Liu, Chunxiang

    2016-02-01

    Superplastic mechanical properties of the AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets produced by twin-roll casting and sequential hot rolling (TRC) were investigated. The AZ31-1.0Y-1.3Sr alloy sheets with the thickness of 1 mm were prepared by twin-roll casting process, which exhibited finer equiaxed grain structure. Uniaxial tensile testing and gas blow forming on AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets were carried out. Results show that the superplastic mechanical properties of AZ31-1.0Y-1.3Sr alloys are better than those of AZ31 alloys at 400 °C and the strain rate of 7 × 10-4/s. The addition of Y and Sr elements is helpful to improve the formability of AZ31 alloy. Grain boundary sliding plays a dominant role in superplastic forming.

  15. Influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Ling; TIAN Su-gui; MENG Fan-lai; DU Hong-qiang

    2006-01-01

    Extrusion treatment is a common method to refine the grain size and improve the mechanical properties of metal material. The influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy was investigated. The results show that the mechanical properties of AZ31 alloy are obviously improved by extrusion treatment. The ultimate tensile strength (UTS) of AZ31 alloy at room temperature is measured to be 222 MPa, and is enhanced to 265.8 MPa after extrusion at 420℃. The yield tensile strength (YTS) of AZ31 alloy at room temperature is measured to be 84 MPa, and is enhanced to 201 MPa after extrusion at 420℃. The effective improvements on mechanical properties result from the formation of the finer grains during extrusion and the finer particles precipitated by age treatment. The features of the microstructure evolution during hot extruded of AZ31 alloy are dislocation slipping on the matrix and occurrence of the dynamic recrystallization.

  16. Corrosion behaviour and in vitro/in vivo biocompatibility of surface-modified AZ31 alloy

    International Nuclear Information System (INIS)

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair. (Author) 18 refs.

  17. Passivity and Localized Corrosion of AZ31 Magnesium Alloy in High pH Electrolytes

    Science.gov (United States)

    Alsagabi, Sultan; Ninlachart, Jakraphan; Raja, Krishnan S.; Charit, Indrajit

    2016-05-01

    Electrochemical corrosion tests were carried out on AZ31 magnesium alloy specimens in pH: 4.5, 9.5, and 13.0 solutions with 0-2000 ppm of chloride additions at room temperature. No passivity breakdown was observed during cyclic polarization in pH:13 solutions containing up to 1500 ppm of chloride. Addition of sodium sulfate and sodium dihydrogen phosphate as supporting electrolytes offset the chloride effect on the corrosion of AZ31 in pH 4.5 and 9.5 solutions. The Mott-Schottky analysis showed the presence of a duplex surface layer consisting of an n-type MgO1-x inner layer (x = 0.024-0.05), and a p-type outer layer which thickened with time at the expense of the inner layer.

  18. Passivity and Localized Corrosion of AZ31 Magnesium Alloy in High pH Electrolytes

    Science.gov (United States)

    Alsagabi, Sultan; Ninlachart, Jakraphan; Raja, Krishnan S.; Charit, Indrajit

    2016-06-01

    Electrochemical corrosion tests were carried out on AZ31 magnesium alloy specimens in pH: 4.5, 9.5, and 13.0 solutions with 0-2000 ppm of chloride additions at room temperature. No passivity breakdown was observed during cyclic polarization in pH:13 solutions containing up to 1500 ppm of chloride. Addition of sodium sulfate and sodium dihydrogen phosphate as supporting electrolytes offset the chloride effect on the corrosion of AZ31 in pH 4.5 and 9.5 solutions. The Mott-Schottky analysis showed the presence of a duplex surface layer consisting of an n-type MgO1- x inner layer ( x = 0.024-0.05), and a p-type outer layer which thickened with time at the expense of the inner layer.

  19. Flow behaviour of magnesium alloy AZ31B processed by equal-channel angular pressing

    Science.gov (United States)

    Arun, M. S.; Chakkingal, U.

    2014-08-01

    Magnesium alloys are characterised by their low density, high specific strength and stiffness. But, the potential application of Mg is limited by its low room-temperature ductility & formability. Formability can be improved by developing an ultrafine grained (UFG) structure. Equal channel angular pressing (ECAP) is a well known process that can be used to develop an ultrafine grained microstructure. The aim of this study was to investigate the flow behaviour of AZ31B magnesium alloy after ECAP. The specimen was subjected to three passes of ECAP with a die angle of 120° using processing route Bc. The processing temperature was 523 K for the first pass and 423 K for the subsequent two passes. The microstructure characterisation was done. Compression tests of ECAPed and annealed specimens were carried out at strain rates of 0.01 - 1s-1 and deformation temperatures of 200 - 300°C using computer servo-controlled Gleeble-3800 system. The value of activation energy Q and the empirical materials constants of A and n were determined. The equations relating flow stress and Zener-Hollomon parameter were proposed. In the case annealed AZ31, the activation energy was determined to be 154 kJ/mol, which was slightly higher than the activation energy of 144 kJ/mol for ECAPed AZ31.

  20. Corrosion and mechanical properties of hot-extruded AZ31 magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    AZ31 magnesium alloys were hot-extruded at 573 K and 623 K with extrusion ratio (λ) of 20, 35 and 50. The corrosion and mechanical behavior of hot-extruded AZ31 were studied by galvanic tests and tensile tests. The microstructures of the studied AZ31 alloys were also investigated with optical microscope. The results show that, compared with the as-cast AZ31 alloy, the corrosion potentials of all hot-extruded AZ31 alloys are increased by 60 mV. Moreover, at the extrusion temperature of 623 K, the galvanic current of AZ31 alloy decreases with increasing extrusion and the galvanic corrosion resistance is increased by 10% with the extrusion ratio of 50. In addition, the tensile strength and elongation of the extruded alloys are significantly enhanced by about 20% and 140%, respectively. The improvement of corrosion resistance and obvious increasing of mechanical properties of AZ31 alloys by hot-extrusion are ascribed to grain refinement and microstructural modification together with the homogeneous distribution of intermetallie phases throughout the matrix.

  1. Characterization of surface products on AZ31 magnesium alloy in dilute NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lei [Materials Reliability Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shinohara, Tadashi, E-mail: SHINOHARA.Tadashi@nims.go.j [Materials Reliability Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Zhang Boping [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Iwai, Hideo [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2009-10-19

    In earlier work, we have drawn a corrosion map of AZ31 Mg alloy in dilute NaCl solutions and determined two zones-corrosion and passivation zones. In this paper, the surface products formed on AZ31 Mg alloy polarized in both zones were characterized in detail by X-ray photoelectron spectroscopy (XPS). MgO, Mg(OH){sub 2}, and MgCO{sub 3} were found in the surface products. Based on these results and previous ones by XRD, Mg(OH){sub 2}, Mg{sub 5}(CO{sub 3}){sub 4}(OH){sub 2}.8H{sub 2}O, and MgO phases were presented in the corrosion zone and the latter two ones were also found in the passivation zone. In the corrosion zone, the higher hydration of the surface components gave a continuous corrosion attack of the metallic surface and degraded the passivation films. In the passivation zone, chloride-induced corrosion was retarded by the formation of the magnesium hydroxyl carbonate product, which provided a protective layer on the material. The adsorption of carbonate played a dual role in the solution. One is that the formation of the soluble salt with co-adsorption of CO{sub 3}{sup 2-} and Cl{sup -} ions accelerated the dissolution of the passivation film. The other is that the formation of the carbonate-containing product served as a protective layer on the surface.

  2. Cytotoxicity studies of AZ31D alloy and the effects of carbon dioxide on its biodegradation behavior in vitro

    International Nuclear Information System (INIS)

    Magnesium alloys have been advocated as potential artificial bone materials due to their biocompatibility and biodegradability. The understanding of their corrosive mechanism in physiological environments is therefore essential for making application-orientated designs. Thus, this in vitro study was designed to assess the effects of CO2 on corrosive behavior of AZ31D to mimic in vivo special ingredient. Electrochemical technologies accompanied with Scanning electron microscope, Fourier transform infrared, X-ray diffraction, Energy dispersive spectroscopy and hydrogen evolution measurement were employed to analyze corrosive rates and mechanisms of AZ31D. Moreover, the biocompatibility of AZ31D was assessed with a direct cell attachment assay and an indirect cytotoxicity test in different diluted extracts. The ion concentrations in extracts were measured using inductively coupled plasma mass spectrometry to offer explanations on the differences of cell viability in the indirect test. The results of the direct cytotoxicity assay showed that the corrosive rate of AZ31D was too rapid to allow for cell adhesion. Extracts diluted less than 20 times would cause adverse effects on cell proliferation, likely due to excessive ions and gas release. Moreover, the presence of CO2 did not cause significant differences on corrosive behavior of AZ31D according to the results of electrochemical testing and hydrogen evolution measurement. This might be caused by the simultaneous process of precipitation and dissolution of MgCO3 due to the penetration role of CO2. This analysis of corrosive atmospheres on the degradation behavior of magnesium alloys would contribute to the design of more scientific in vitro testing systems in the future. - Highlights: • We evaluate the effects of CO2 on corrosion behavior of magnesium alloys. • We assess the feasibility of commercial AZ31D alloy as potential implants. • CO2 is not the key factor to minimize the gap of in vitro and in vivo

  3. Increased room temperature formability of Mg AZ31 by high speed Friction Stir Processing

    International Nuclear Information System (INIS)

    Highlights: • High speed FSP was performed on Mg AZ31 at processing speeds between 1 and 10 m/min. • Process zone EBSD analysis revealed deformation prone microstructure and texture. • The TMAZ featured low aspect ratio grains, with high mounts of HAB. • Formability tests revealed increases of up to 100% over the base material. • Local anisotropy was most present in the tensile regime of the FLD. - Abstract: The aim of this work is to investigate the formability at room temperature of the Mg alloy AZ31 by Friction Stir Processing. Defect-free process zones were created using process speeds of up to 10 m/min, the resulting microstructure and grain size were analyzed. Microstructural zones with varying texture were identified by electron backscatter diffraction. Tensile tests supported by digital image correlation analysis revealed different deformation behavior and enhanced ductility in the thermo mechanically affected zone which was associated with the variation in grain size and texture. Finally, the sheet forming behavior of the processed material was investigated, using the Nakajima test method with Hasek specimen geometries. Forming limit diagrams for several process conditions reveal a continuous increase in formability with increasing processing speed. Additionally, the local anisotropy was analyzed by comparison of the R values at the point of highest strain, to quantify the impact of processing on formability

  4. Effect of Carbon Nanotube on High-Temperature Formability of AZ31 Magnesium Alloy

    Science.gov (United States)

    Hassan, S. Fida; Paramsothy, M.; Gasem, Z. M.; Patel, F.; Gupta, M.

    2014-08-01

    Room-temperature tensile properties of AZ31 alloy have significantly been improved when reinforced with carbon nanotube via ingot metallurgy process. However, high-temperature (up to 250 °C) elongation-to-failure tensile test of the developed nanocomposite revealed a considerable softening in the AZ31 alloy matrix accompanied by an incredible ductility increment (up to 132%). Microstructural characterization of the fractured samples revealed that the dynamic recrystallization process has induced a complete recrystallization in the AZ31 alloy at a lower temperature (150 °C) followed by substantial grain growth at a higher temperature used in this study. Fractography on the fractured surfaces revealed that the room-temperature mixed brittle-ductile modes of fracture behavior of AZ31 alloy have transformed into a complete ductile mode of fracture at high temperature.

  5. The oxidation resistance and ignition temperature of AZ31 magnesium alloy with additions of La2O3 and La

    International Nuclear Information System (INIS)

    Highlights: ► Using lanthanum and lanthanum oxide (La2O3) can improve oxidation resistance of magnesium alloy. ► La2O3 is as effective as La in affecting both alloy microstructure and oxidation resistance. ► The optimum La concentration in alloy is ∼0.7 wt.%. ► We analyzed the oxidation kinetics of AZ31 alloy with both additions. - Abstract: We investigate the oxidation resistance of AZ31 magnesium alloy with additions of La and La oxide (La2O3). The contributor is the practical La content in alloy. Both La and La2O3 are effective in improving the oxidation resistance of Mg alloys. The samples with La content of ∼ 0.7 wt.% possess the best resistance to oxidation of all. Oxide scale, ignition temperature and oxidation kinetics are analyzed. However, higher La content is detrimental to the oxidation resistance.

  6. The fluoride coated AZ31B magnesium alloy improves corrosion resistance and stimulates bone formation in rabbit model.

    Science.gov (United States)

    Sun, Wei; Zhang, Guangdao; Tan, Lili; Yang, Ke; Ai, Hongjun

    2016-06-01

    This study aimed to evaluate the effect of fluorine coated Mg alloy and clarify its mechanism in bone formation. We implanted the fluorine coated AZ31B Mg alloy screw (group F) in rabbit mandibular and femur in vivo. Untreated AZ31B Mg alloy screw (group A) and titanium screw (group T) were used as control. Then, scanning electron microscopy, the spectral energy distribution analysis, hard and decalcified bone tissues staining were performed. Immunohistochemistry was employed to examine the protein expressions of bone morphogenetic protein 2 (BMP-2) and collagen type I in the vicinity of the implant. Compared with the group A, the degradation of the alloy was reduced, the rates of Mg corrosion and Mg ion release were slowed down, and the depositions of calcium and phosphate increased in the group F in the early stage of implantation. Histological results showed that fluorine coated Mg alloy had well osteogenic activity and biocompatibility. Moreover, fluoride coating obviously up-regulated the expressions of collagen type I and BMP-2. This study confirmed that the fluorine coating might improve the corrosion resistance of AZ31B Mg alloy and promote bone formation by up-regulated the expressions of collagen type I and BMP-2. PMID:27040245

  7. Weldability of A7075-T651 and AZ31B dissimilar alloys by MIG welding method based on welding appearances

    International Nuclear Information System (INIS)

    It is not recommended to weld aluminium and magnesium dissimilar alloys using fusion welding method because of the formation of AlmMgn type intermetallic brittle compounds like Mg2Al3, Mg17Al12 etc. in the welding joint. These brittle compounds deteriorate the mechanical properties of the joint. But so far, insufficient researches have been attempted to stop the formation of AlmMgn type intermetallic brittle compounds in fusion welding method. The aim of this research work was to investigate on the weldability between A7075-T651 and AZ31B dissimilar alloys based on welding appearances and study the formation of intermetallic brittle compounds at the joint. In this research, A7075-T651 and AZ31B alloys were welded using ER5356 filler wire in MIG welding method in butt configuration. 100% argon was used as shielding gas. The results showed that, most of the welding appearances were moderate. The macroscopic investigation at all welding cross section showed that a lot of AlmMgn intermetallic brittle compounds were formed at the interface between weld seam and AZ31B parent metal side which caused macro cracks. A good number of macro pores were also observed at AZ31B parent metal side. These cracks and pores could easily cause the failure of the joint at very low stress.

  8. Warm Deep Drawing Of Rectangular Cups With Magnesium Alloy AZ31 Sheets

    International Nuclear Information System (INIS)

    Recently, magnesium alloys have been widely applied in automotive and electronic industries as the lightest weight structural and functional materials. Warm forming of magnesium alloys has attracted much attention due to the very poor formability of Mg alloys at room temperature. The formability of magnesium alloy sheet at elevated temperature is significantly affected by the processing parameters. Among them the forming temperature, the punch speed, the geometrical shape of the blank, the blank holder force and the lubrication are probably the most relevant. In this research, the deep drawing of rectangular cups with AZ31 sheets was conducted at elevated temperatures with different process parameters. The finite element analyses were performed to investigate the effects of the process parameters on the formability of rectangular cup drawing and to predict the process defects during the process. The material yield condition was modeled using the isotropic Von Mises criterion. The flow stress data were obtained from tensile tests

  9. High power fiber laser arc hybrid welding of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: ► Fiber laser–metal inert gas arc hybrid welding of AZ31B Mg alloy was developed. ► The maximum tensile strength efficiency of 5 mm thick welds is up to 109%. ► Grain size of fusion zone and width of PMZ both increase with heat input. ► Hall–Petch relationship between microhardness and grain size is obtained. ► Strength difference between 5 mm and 8 mm thick welds is summarized and discussed. -- Abstract: High power fiber laser–metal inert gas arc hybrid welding of AZ31B magnesium alloy was studied. The fusion zone consisted of hexagonal dendrites, where the secondary particle of Al8Mn5 was found at the center of dendrite as a nucleus. Within hybrid weld, the arc zone had coarser grain size and wider partial melted zone compared with the laser zone. The tensile results showed the maximum strength efficiency of 5 mm thick welds was up to 109%, while that of 8 mm thick welds was only 88%. The fracture surface represented a ductile–brittle mixed pattern characterized by dimples and quasi-cleavages. On the fracture surface some metallurgical defects of porosity and MgO inclusions around with secondary cracks were observed. Meanwhile, a strong link between the joint strength and weld porosity were demonstrated by experimental results, whose relevant mechanism was discussed by the laser–arc interaction during hybrid welding.

  10. Influence of inorganic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.;

    2009-01-01

    Surface contaminants as a result of thermo-mechanical processing of magnesium alloys, e.g. sheet rolling, can have a negative effect on the corrosion resistance of magnesium alloys. Especially contaminants such as Fe, Ni and Cu, left on the surface of magnesium alloys result in the formation...... of micro-galvanic couples and can therefore increase corrosion attack on these alloys. Due to this influence they should be removed to obtain good corrosion resistance. In this study, the effect of inorganic acid pickling on the corrosion behaviour of a commercial AZ31 magnesium alloy sheet...... cleaning the AZ31 sheet. However, to obtain reasonable corrosion resistance at least 5 mu m of the surface of AZ31 magnesium alloy sheet have to be removed....

  11. Influence of Surface Condition on Expulsion in Spot Welding AZ31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Yarong WANG; Jicai FENG; Zhongdian ZHANG

    2005-01-01

    Experiments were carried out to study the influence of surface condition on expulsion during the spot welding of AZ31B Mg alloy. A general electrical contact resistance theory for conductive rough surfaces and the relation between maximum temperature Tm in the contact and voltage-drop V across interface of two surfaces were employed to understand the reason of expulsion in Mg alloy spot welding. The main reason of expulsion is that the high electrical contact resistance induced by large roughness of the surface and oxide film covered on the surface leads to local melting of metal in the interface of two surfaces, and liquid metal of the local area ejected from the specimen under electrode force forms expulsion.

  12. Interface microstructure and mechanical properties of zinc–aluminum thermal diffusion coating on AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: • The microstructure evolutions of Zn–Al thermal diffusion coating on AZ31Mg alloy were analyzed. • The phase constitution of interfacial layer was identified. • The surface hardness of AZ31 magnesium substrate with Zn–Al alloy coating was improved. - Abstract: The zinc–aluminum (Zn–Al) alloy coating with excellent wear and corrosion resistance was fabricated on the surface of magnesium substrate (AZ31) using thermal diffusion technique. The microstructure, phase constitution and chemical composition were investigated. The experimental observation exhibited that the interfacial microstructures were composed of network eutectic structures and lamellar eutectoid structures at heating temperature of 350 °C for holding time of 30 min under 0.1 MPa in a vacuum of 10−3 Pa. X-ray diffraction (XRD) pattern analysis identified that α-Mg, Mg7Zn3 and MgZn phases were formed in the diffusion layer. The interdiffusion of Mg and Al atoms were restricted by Mg–Zn intermetallic compounds (IMCs). The value of microhardness at the diffusion layer increased due to the formation of Mg–Zn eutectic phases. This technique is beneficial to improving poor wear and corrosion resistance of magnesium alloy

  13. Investigation of the chemical vicinity of defects in Mg and AZ31 with positron coincident Doppler boarding spectroscopy

    International Nuclear Information System (INIS)

    Within the scope of the present work, two main goals have been achieved: Firstly, the coincident Doppler broadening spectrometer (CDBS) at the high intense positron source NEPOMUC has been elaborately improved in order to increase the spatial resolution for defect mapping measurements and to investigate samples with shallow positron trapping sites which are present e. g. in magnesium. Secondly, as an application, the chemical vicinity of defects in the industrially used magnesium based alloy AZ31 has been examined by means of the detailed investigation of ion-irradiated specimen with positron annihilation spectroscopy. Detailed simulations with the finite-element simulation tool COMSOL were used to optimize the focal diameter of the positron beam at the sample position in order to increase the spatial resolution. With a value of 0.3 mm, sub-mm resolution has now been reached. The CDBS has been furthermore equipped with a sample cooling unit in order to reach liquid nitrogen temperature, maintaining the feature of scanning the sample for defect mapping. Defects and their chemical surrounding in ion irradiated magnesium and the magnesium based alloy AZ31 were then investigated on an atomic scale with the CDBS. In the respective spectra the chemical information and the defect contribution have been thoroughly separated. For this purpose, samples of annealed Mg were irradiated with Mg-ions in order to create exclusively defects. In addition Al- and Zn-ion irradiations on Mg-samples were performed in order to create samples with both defects and impurity atoms. The ion irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy (DBS) and compared with SRIM-simulations of the vacancy distribution. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with CDBS on Mg-ion irradiated AZ31 with Mg-ion irradiated Mg. The outer tail of the energy distribution in the annihilation

  14. In vitro and in vivo studies of biodegradable fine grained AZ31 magnesium alloy produced by equal channel angular pressing.

    Science.gov (United States)

    Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh; Devi Prasad, V; Raghunath, M

    2016-02-01

    The objective of the present work is to investigate the role of different grain sizes produced by equal channel angular pressing (ECAP) on the degradation behavior of magnesium alloy using in vitro and in vivo studies. Commercially available AZ31 magnesium alloy was selected and processed by ECAP at 300°C for up to four passes using route Bc. Grain refinement from a starting size of 46μm to a grain size distribution of 1-5μm was successfully achieved after the 4th pass. Wettability of ECAPed samples assessed by contact angle measurements was found to increase due to the fine grain structure. In vitro degradation and bioactivity of the samples studied by immersing in super saturated simulated body fluid (SBF 5×) showed rapid mineralization within 24h due to the increased wettability in fine grained AZ31 Mg alloy. Corrosion behavior of the samples assessed by weight loss and electrochemical tests conducted in SBF 5× clearly showed the prominent role of enhanced mineral deposition on ECAPed AZ31 Mg in controlling the abnormal degradation. Cytotoxicity studies by MTT colorimetric assay showed that all the samples are viable. Additionally, cell adhesion was excellent for ECAPed samples particularly for the 3rd and 4th pass samples. In vivo experiments conducted using New Zealand White rabbits clearly showed lower degradation rate for ECAPed sample compared with annealed AZ31 Mg alloy and all the samples showed biocompatibility and no health abnormalities were noticed in the animals after 60days of in vivo studies. These results suggest that the grain size plays an important role in degradation management of magnesium alloys and ECAP technique can be adopted to achieve fine grain structures for developing degradable magnesium alloys for biomedical applications. PMID:26652384

  15. Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Gu Yanhong, E-mail: ygu2@alaska.edu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Chen Chengfu [Department of Mechanical Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Bandopadhyay, Sukumar [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Ning Chengyun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Zhang Yongjun [Department of Mining Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Guo Yuanjun [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

    2012-06-01

    This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

  16. Research on Thermal Deep-drawing Technology of Magnesium Alloy(AZ31B) Sheets

    Institute of Scientific and Technical Information of China (English)

    Sfihong ZHANG; Kun ZHANG; Zhongtang WANG; Chuanfu YU; Yi XU; Qiang WANG

    2004-01-01

    Forming technology of Mg alloy (AZ31B) sheets can be investigated by thermal deep drawing experiments. In the experiments,the blank holder and die contacting with the blank were heated to the same temperature as the blank by using the heating facility. The circular blank heated in an oven is formed at a temperature range of 100~400℃ to obtain the optimum forming temperature range and the effects of major technical parameters on the workpiece quality. It is found that the blank is brittle at temperatures lower than 200℃. Temperatures higher than 400℃ are not suitable for forming of the sheets because of severe oxidation and wrinkling. AZ31B shows an excellent formability at temperatures from 300 to 350℃ and can be formed into a workpiece with good quality. When the blank holder force is 99 Kn, extruded sheets with a thickness of 1 mm can be formed into cups without wrinkling. Workpieces show strong anisotropic deformation behavior on the flanges.

  17. Effect of hot working on the damping capacity and mechanical properties of AZ31 magnesium alloy

    Science.gov (United States)

    Lee, K.; Kang, C.; Kim, K.

    2015-04-01

    Magnesium alloys have received much attention for their lightweight and other excellent properties, such as low density, high specific strength, and good castability, for use in several industrial and commercial applications. However, both magnesium and its alloys show limited room-temperature formability owing to the limited number of slip systems associated with their hexagonal close-packed crystal structure. It is well known that crystallographic texture plays an important role in both plastic deformation and macroscopic anisotropy of magnesium alloys. Many authors have concentrated on improving the room- temperature formability of Mg alloys. However, despite having a lot of excellent properties in magnesium alloy, the study for various properties of magnesium alloy have not been clarified enough yet. Mg alloys are known to have a good damping capacity compared to other known metals and their alloys. Also, the damping properties of metals are generally recognized to be dependent on microstructural factors such as grain size and texture. However, there are very few studies on the relationship between the damping capacity and texture of Magnesium alloys. Therefore, in this study, specimens of the AZ31 magnesium alloy, were processed by hot working, and their texture and damping property investigated. A 60 mm × 60 mm × 40 mm rectangular plate was cut out by machining an ingot of AZ31 magnesium alloy (Mg-3Al-1Zn in mass%), and rolling was carried out at 673 K to a rolling reduction of 30%. Then, heat treatment was carried out at temperatures in the range of 573-723 K for durations in the range of 30-180 min. The samples were immediately quenched in oil after heat treatment to prevent any change in the microstructure. Texture was evaluated on the compression planes by the Schulz reflection method using nickel-filtered Cu Kα radiation. Electron backscatter diffraction measurements were conducted to observe the spatial distribution of various orientations. Specimens

  18. Effects of organic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.; Dietzel, W.; Kainer, K. U.

    2010-01-01

    mu m of the contaminated surface was required to reach corrosion rates less than 1 mm/year in salt spray condition. Among the three organic acids examined, acetic acid is the best choice. Oxalic acid can be an alternative while citric acid is not suitable for cleaning AZ31 sheet, because of......Organic acids were used to clean AZ31 magnesium alloy sheet and the effect of the cleaning processes on the surface condition and corrosion performance of the alloy was investigated. Organic acid cleanings reduced the surface impurities and enhanced the corrosion resistance. Removal of at least 4...

  19. Cytotoxicity studies of AZ31D alloy and the effects of carbon dioxide on its biodegradation behavior in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiali, E-mail: wangjialicsu@yahoo.cn [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Qin, Ling [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Wang, Kai [School of Humanities and Social Sciences, Hunan University of Chinese Medicine, Changsha 410208 (China); Wang, Jue; Yue, Ye [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Li, Yangde [Guangdong Innovation Team for Biodegradable Magnesium and Medical Implants, E-ande, Dongguan 523660 (China); Tang, Jian [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Li, Weirong [Guangdong Innovation Team for Biodegradable Magnesium and Medical Implants, E-ande, Dongguan 523660 (China)

    2013-10-01

    Magnesium alloys have been advocated as potential artificial bone materials due to their biocompatibility and biodegradability. The understanding of their corrosive mechanism in physiological environments is therefore essential for making application-orientated designs. Thus, this in vitro study was designed to assess the effects of CO{sub 2} on corrosive behavior of AZ31D to mimic in vivo special ingredient. Electrochemical technologies accompanied with Scanning electron microscope, Fourier transform infrared, X-ray diffraction, Energy dispersive spectroscopy and hydrogen evolution measurement were employed to analyze corrosive rates and mechanisms of AZ31D. Moreover, the biocompatibility of AZ31D was assessed with a direct cell attachment assay and an indirect cytotoxicity test in different diluted extracts. The ion concentrations in extracts were measured using inductively coupled plasma mass spectrometry to offer explanations on the differences of cell viability in the indirect test. The results of the direct cytotoxicity assay showed that the corrosive rate of AZ31D was too rapid to allow for cell adhesion. Extracts diluted less than 20 times would cause adverse effects on cell proliferation, likely due to excessive ions and gas release. Moreover, the presence of CO{sub 2} did not cause significant differences on corrosive behavior of AZ31D according to the results of electrochemical testing and hydrogen evolution measurement. This might be caused by the simultaneous process of precipitation and dissolution of MgCO{sub 3} due to the penetration role of CO{sub 2}. This analysis of corrosive atmospheres on the degradation behavior of magnesium alloys would contribute to the design of more scientific in vitro testing systems in the future. - Highlights: • We evaluate the effects of CO{sub 2} on corrosion behavior of magnesium alloys. • We assess the feasibility of commercial AZ31D alloy as potential implants. • CO{sub 2} is not the key factor to minimize

  20. In vitro Study on Biodegradable AZ31 Magnesium Alloy Fibers Reinforced PLGA Composite

    Institute of Scientific and Technical Information of China (English)

    Y.H.Wu; N.Li; Y.Cheng; Y.F.Zheng; Y.Han

    2013-01-01

    AZ31 magnesium alloy fibers reinforced poly(lactic-co-glycolic acid) (PLGA) composites were prepared and their mechanical property,immersion corrosion behavior and biocompatibility were studied.The tensile test showed that with the addition of AZ31 fibers,the composites had a significant increment in tensile strength and elongation.For the direct cell attachment test,all the cells showed a healthy morphology and spread well on the experimental sample surfaces.The immersion results indicated that pH values of the immersion medium increased with increasing AZ31 fiber contents.All the in vitro experimental results indicated that this new kind of magnesium alloy fibers reinforced PLGA composites show a potential for future biomedical applications.

  1. Microstructure and mechanical properties of wrought magnesium alloy AZ31B welded by laser-TIG hybrid

    Institute of Scientific and Technical Information of China (English)

    刘黎明; 宋刚; 王继锋; 梁国俐

    2004-01-01

    The laser-TIG hybrid welding was mainly used to weld the wrought magnesium alloy AZ31B. The technical characteristics of laser-TIG hybrid welding process was investigated and the interactional mechanism between laser and arc was discussed, at the same time the microstructure and mechanical properties of the wrought magnesium alloy AZ31B using laser-TIG hybrid welding were analyzed by optical microscope, EPMA, SEM, tensile machine, hardness machine. The experimental results show that the presence of laser beam boosts up the stability of the arc during high speed welding and augments the penetration of weld; the crystal grains of magnesium alloy weld are fine without porosity and cracks in the best welding criterion and the microstructure of HAZ does not become coarse obviously. The elements profile analysis reveals that Mg content in the weld is lower than that of the base metal, but Al content is higher slightly. Under this experimental condition, the wrought magnesium alloy AZ31B joint can be achieved using laser-TIG hybrid process and the tensile strength of the joint is equivalent to that of the base metal.

  2. Evolution of microstructure and hardness in AZ31 alloy processed by high pressure torsion

    International Nuclear Information System (INIS)

    A commercial MgAlZn alloy (AZ31) was processed by high pressure torsion (HPT) at room temperature, resulting in an extreme microstructure refinement down to the grain size of 150–250 nm. The microstructure evolution during HPT was investigated by transmission electron microscopy and X-ray diffraction line profile analysis. The microhardness was measured as a function of the distance from the center of the disk and the number of HPT revolutions. The detailed analysis of dislocation contrast factors in X-ray diffraction line profiles enables to determine the population of the different slip systems as a function of the imposed strain. The influence of microstructure and defect structure evolution on microhardness is discussed in detail

  3. HIGH STRAIN RATE BEHAVIOUR OF AN AZ31 + 0.5 Ca MAGNESIUM ALLOY

    Directory of Open Access Journals (Sweden)

    Josef Pešička

    2012-01-01

    Full Text Available The paper reports behaviour of magnesium alloy AZ31 (nominal composition 3 % Al - 1 % Zn – balance Mg with an addition of 0.5 wt. % Ca at high strain rates. Samples were prepared by the squeeze cast technology. Dynamic compression Hopkinson tests were performed at room temperature with impact velocities ranging from 11.2 to 21.9 m.s-1. A rapid increase of the flow stress and the strain rate sensitivity was observed at high strain rates. Transmission electron microscopy showed extremely high dislocation density and mechanical twins of two types. Adiabatic shear banding is discussed as the reason for the observed behaviour at high strain rates.

  4. Statistical analysis on static recrystallization texture evolution in cold-rolled AZ31 magnesium alloy sheet.

    Science.gov (United States)

    Park, Jun-Ho; Ahn, Tae-Hong; Choi, Hyun-Sik; Chung, Jung-Man; Kim, Dong-Ik; Oh, Kyu Hwan; Han, Heung Nam

    2013-08-01

    Cast AZ31B-H24 magnesium alloy, comprising Mg with 3.27 wt% Al and 0.96 wt% Zn, was cold rolled and subsequently annealed. Global texture evolutions in the specimens were observed by X-ray diffractometry after the thermomechanical processing. Image-based microstructure and texture for the deformed, recrystallized, and grown grains were observed by electron backscattered diffractometry. Recrystallized grains could be distinguished from deformed ones by analyzing grain orientation spread. Split basal texture of ca. ±10-15° in the rolling direction was observed in the cold-rolled sample. Recrystallized grains had widely spread basal poles at nucleation stage; strong {0001} basal texture developed with grain growth during annealing. PMID:23920167

  5. Effect of rolling reduction on microstructure, texture, mechanical properties and mechanical anisotropy of AZ31 magnesium alloys

    International Nuclear Information System (INIS)

    Mechanical properties of as-rolled magnesium alloy sheets show an obvious anisotropy during rolling. To get sheets with excellent performance and investigate the effect of microstructure, texture on mechanical properties and mechanical anisotropy, AZ31 magnesium alloy sheets with 4 mm in thickness were obtained by multi-pass hot rolling using different single pass rolling reductions. The texture evolution of the as-rolled AZ31 magnesium sheets was analyzed by the electron backscattered diffraction (EBSD) method. The Hall–Petch and Schmid law effect were discussed in detail on the basis of experiment. A revised form of Hall–Petch formula was proposed with the consideration of texture effect as σs−t=(0.3/mt)(σ0+kd−1/2). The mechanical properties were greatly enhanced by multi-pass hot rolling and the enhancement was attributed to both grain refinement and texture intensity. The results would provide useful guidance to design a rolling processing route for AZ31 Mg Alloys sheet

  6. Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys

    OpenAIRE

    Feliu Jr., S.; Pardo, Angel; Merino, M. C.; Coy, A. E.; Viejo, F.; Arrabal, R.

    2009-01-01

    X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 °C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH)2 and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of M...

  7. Comparison of corrosion behaviors of AZ31, AZ91,AM60 and ZK60 magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    CHENG Ying-liang; QIN Ting-wei; WANG Hui-min; ZHANG Zhao

    2009-01-01

    The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60>AM60>AZ31>AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.

  8. Protection of the AZ31 magnesium alloy with cerium modified silane coatings

    International Nuclear Information System (INIS)

    Highlights: → Silane conversion coatings as possible alternative to Cr(VI) based pre-treatments. → 3-mercapto-propyl-trimethoxysilane (PropS-SH) tested on Mg alloys. → PropS-SH forms a porous conversion coating which allows a rapid electrolyte uptake. → Ce(NO3)3 addition to pre-treatment bath improves PropS-SH coating performance. → Ce3+ ions presence provides self-healing feature to the coating. - Abstract: This research investigates the effect of cerium ion addition on the efficiency of a 3-mercapto-propyl-trimethoxysilane (PropS-SH) coating formed on AZ31 magnesium alloy. The coating was obtained by dipping AZ31 coupons in a hydroalcoholic 3-mercapto-propyl-trimethoxysilane solution, added with cerium nitrate, in order to obtain a 5 x 10-3 or 5 x 10-4 M Ce+3 ion concentration. The silane baths were regulated at pH 4 and utilized for filming treatment after 48 h following their preparation. The treated specimens were finally cured for 1 h at 100 deg. C. The protective efficiency of cerium modified and unmodified PropS-SH coatings was evaluated by recording potentiodynamic polarization curves and electrochemical impedance spectra in a 0.1 M NaCl environment. In comparison to PropS-SH coating, cerium nitrate modified silane layer exhibited noticeably improved performances, in particular in presence of a 5 x 10-3 M Ce3+ concentration. The increased protectiveness and stability of the modified coatings were attributed to a lower porosity and defectiveness and to self-healing ability provided by Ce3+ ion presence.

  9. Improved Corrosion Resistance of Magnesium Alloys AZ31 and AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    HAO Sheng- zhi; GAO Bo; ZHOU Ji-yang; DONG Chuang

    2004-01-01

    Surface treatment of magnesium alloys AZ31 and AZ91HP by a high current pulsed electron beam (HCPEB)was investigated in the present paper. The corrosion resistance of treated samples was tested in a 5% (wt%) NaCl solution,showing remarkably improvement as manifested by polarization curves. According to EPMA analysis, the intermetallic Mg17Al12 in the surface layer of AZ91HP sample almost disappeared after the treatment of HCPEB, leaving the surface layer in a state of supersaturated solid solution. Both the augmentation of aluminum content and the formation of supersaturated structure in the surface layer are believed to contribute to the improved corrosion resistance of AZ31 and AZ91HP.

  10. Improved Corrosion Resistance of Magnesium Alloys AZ31 and AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    HAOSheng-zhi; GAOBo; ZHOUJi-yang; DONGChuang

    2004-01-01

    Surface treatment of magnesium alloys AZ31 and AZ91HP by a high current pulsed electron beam (HCPEB) was investigated in the present paper. The corrosion resistance of treated samples was tested in a 5% (wt%) NaCl solution, showing remarkably improvement as manifested by polarization curves. According to EPMA analysis, the intermetallic Mg17Al12 in the surface layer of AZ91HP sample almost disappeared after the treatment of HCPEB, leaving the surface layer in a state of supersaturated solid solution. Both the augmentation of aluminum content and the formation of supersaturated structure in the surface layer are believed to contribute to the improved corrosion resistance of AZ31 and AZ91HP.

  11. Formability of AZ31 magnesium alloy sheets during magnetic pulse bulging

    International Nuclear Information System (INIS)

    Electromagnetic forming (EMF), i.e., magnetic pulse forming, with and without an Al driver sheet is experimentally performed to investigate the formability of an AZ31 magnesium alloy sheet during high speed forming. The formability of the magnesium alloy AZ31 during EMF is compared with that during traditional quasi-static tests. The results show that the formability of the magnesium alloy sheet undergoing the EMF process without the driver sheet is increased compared with that during quasi-static tests. To improve the energy efficiency of and to accelerate the AZ31 sheet, an Al driver sheet was used. The energy efficiency increases from 0.2% (no driver) to 1.8% (with a 2 mm driver sheet). The forming limits of the magnesium alloy samples with the 2 mm driver sheet are dramatically higher than those during quasi-static tests. The major and minor principal strains with the 2 mm Al driver sheet increase by approximately 148% and 184%. The forming limits with 0.5 and 1 mm driver sheets are similar to those during the EMF process without the driver sheet, enabling the AZ31 sheet to be formed at a higher strain. Increases in the major and minor principal strains with the 0.5 mm driver sheet of approximately 68% and 72%, respectively, are achieved. According to the analysis of the crack fracture observations of the samples with the driver sheets, the fracture surfaces have obvious plastic dimples, which exhibit typical ductile rupture. The test results indicate that the formability could be significantly improved. The EMF process could be used in the manufacturing of AZ31 magnesium alloy sheet parts at room temperature

  12. Corrosion behaviour and in vitro/in vivo biocompatibility of surface-modified AZ31 alloy; Comportamiento frente a la corrosion y biocompatibilidad in vitrolin vivo de la aleacion AZ31 modificada superficialmente

    Energy Technology Data Exchange (ETDEWEB)

    Carboneras, M.; Iglesias, C.; Perez-Maceda, B. T.; Valle, J. A. de; Garcia-Alonso, M. C.; Alobera, M. A.; Clemente, C.; Rubio, J. C.; Escudero, M. I.; Lozano, R. M.

    2011-07-01

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair. (Author) 18 refs.

  13. Evolution of rheocast microstructure of AZ31 alloy in semisolid state

    Directory of Open Access Journals (Sweden)

    Xing Bo

    2013-07-01

    Full Text Available Semisolid rheoforming (SSR is a promising technology for the production of Mg wrought alloy in foundry settings. In order to realize SSR, it is necessary to characterize the grain structure evolution during slurry preparation. In this paper, slurry of AZ31 alloy was produced by a novel rheocast process known as self-inoculation method (SIM. Interrupted quenching technology was applied to investigate the primary α-Mg evolution during continuous cooling and isothermal holding. Results indicate that the initial microstructure of slurry produced by SIM is a mixture of irregular grains, which becomes ideally globular when the slurry slowly cools to 620 ℃ and isothermally held for at least 30 s. The local solute diffusion leads to dendritic fragmentation and forms separated particles. During prolonged holding, the particle surface gradually becomes smooth because of protuberance melting and groove advancement. Coarsening of α-Mg grains in isothermal holding was analyzed using Lifshitz-Slyozov-Wagner theory. Results suggest that coalescence is most likely the dominant coarsening mechanism in the early stage while Ostwald ripening tends to be the principal one later. The EDS results indicate that a longer holding time leads to Al solute element segregation at the grain boundaries, but Zn distribution within liquid matrix has no obvious change.

  14. Tailoring degradation of AZ31 alloy by surface pre-treatment and electrospun PCL fibrous coating.

    Science.gov (United States)

    Hanas, T; Sampath Kumar, T S; Perumal, Govindaraj; Doble, Mukesh

    2016-08-01

    AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO3 to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO3 treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359-09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO3 pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys. PMID:27157726

  15. Magnetic force improvement and parameter optimization for magnetic abrasive polishing of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetic force acting on workpieee to be machined plays a significantly important role in magnetic abrasive polishing process.But in a case of polishing nonferrous materials,the strength of magnetic force is very low and it leads lower polishing efficiency.The magnesium alloy that has superior mechanical properties for industrial application such as a lightweight and high specific strength is one of the most famous nonferrous materials.An improving strategy of the magnetic force for me AZ31 magnesium alloy installed with a permanent magnet was proposed and experimental verification Was carded out.For the proposed strategy,the effect of process parameters on the surface roughness of the AZ31 magnesium alloy Was evaluated by a design of experimental method.

  16. Effects of CH3OH Addition on Plasma Electrolytic Oxidation of AZ31 Magnesium Alloys

    Science.gov (United States)

    He, Yongyi; Chen, Li; Yan, Zongcheng; Zhang, Yalei

    2015-09-01

    Plasma electrolytic oxidation (PEO) films on AZ31 magnesium alloys were prepared in alkaline silicate electrolytes (base electrolyte) with the addition of different volume concentrations of CH3OH, which was used to adjust the thickness of the vapor sheath. The compositions, morphologies, and thicknesses of ceramic layers formed with different CH3OH concentrations were determined via X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion behavior of the oxide films was evaluated in 3.5 wt.% NaCl solution using potentiodynamic polarization tests. PEO coatings mainly comprised Mg, MgO, and Mg2SiO4. The addition of CH3OH in base electrolytes affected the thickness, pores diameter, and Mg2SiO4 content in the films. The films formed in the electrolyte containing 12% CH3OH exhibited the highest thickness. The coatings formed in the electrolyte containing different concentrations of CH3OH exhibited similar corrosion resistance. The energy consumption of PEO markedly decreased upon the addition of CH3OH to the electrolytes. The result is helpful for energy saving in the PEO process. supported by National Natural Science Foundation of China (No. 21376088), the Project of Production, Education and Research, Guangdong Province and Ministry of Education (Nos. 2012B09100063, 2012A090300015), and Guangzhou Science and Technology Plan Projects of China (No. 2014Y2-00042)

  17. Laser welding of AZ31B magnesium alloy to Zn-coated steel

    International Nuclear Information System (INIS)

    Highlights: ► Magnesium alloy was successfully laser welded to Zn-coated steel. ► The joint strength exceeded 6000 N on a 25 mm wide specimen. ► A 450 nm thick layer of Fe3Al was uniformly formed on the steel surface. -- Abstract: The characteristics of laser lap welding of AZ31B magnesium alloy to Zn-coated steel were investigated. Welding was difficult when the laser beam was irradiated onto the AZ31B alloy and the processing parameters were set to obtain a keyhole welding mode. The difference in the physical properties between the two materials resulted in unstable welding process particularly when the laser beam penetrated into the steel specimen and a keyhole was formed therein. By switching to a conduction mode, the process stability was improved and successful welding could be achieved because the liquid metal film remained unbroken and the laser beam did not penetrate into the material. A 25 mm wide joint failed in tensile shear testing at loads exceeding 6000 N. This high joint strength was attributed to the formation of a 450 nm thick layer of Fe3Al intermetallic compound on the steel surface as a result of the interaction between Al from the AZ31B alloy and Fe. The presence of Zn-coating layer was essential to eliminate the negative effects of oxides on the joining process.

  18. Hot deformation behavior of a spray-deposited AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    LI Yongbing; CHEN Yunbo; CUI Hua; DING Jie; ZUO Lingli; ZHANG Jishan

    2009-01-01

    The flow stress behavior of an as-spray-deposited AZ31 magnesium alloy with fine grains was investigated by means of compression tests with a Gleeble 1500 thermal mechanical simulator at isothermal constant strain rates of 0.01, 0.1, 1.0, and 10 s-1; the testing temperatures ranged from 623 to 723 K. It is demonstrated that a linear equation can be fitted between the Zemer-Hollomon parameter Z and stress in a double-log scale. The effect of deformation parameters on the behavior of recrystallization was analyzed. Dynamic recrystallization (DRX) generally occurs at a higher temperature and at a lower strain rate. The constitutive equation of the spray-deposited AZ31 magnesium alloy is elevated temperatures due to the fine grain, which provides a large amount of nucleation sites and a high-diffnsivity path for the atom.

  19. Dynamic recrystallization and texture development during hot deformation of magnesium alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    YANG Xu-yue; JI Ze-sheng; H. MIURA; T. SAKAI

    2009-01-01

    The dynamic recrystallization(DRX) and texture development, taking place during hot deformation of magnesium alloy AZ31 with a strong wire texture, were studied in compression at 673 K (0.73 Tm). Two kinds of samples were machined parallelly to the extruded and transverse directions of Mg alloy rods. New fine grains are evolved at original grain boundaries corrugated at low strains and develop rapidly in the medium range of strain, finally leading to a roughly full evolution of equiaxial fine grains. Kink bands are evolved at grain boundaries corrugated and also frequently in grain interiors at low strains. The boundary misorientations of kink band increase rapidly with increasing strain and approach a saturation value in high strain. The average size of the regions fragmented by kink band is almost the same as that of new grains evolved in high strain. These characteristics of new grain evolution process are not changed by the orientation of the samples, while the flow behaviors clearly depend on it. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction, i.e. continuous dynamic recrystallization(DRX). The latter is discussed by comparing with conventional, i.e. discontinuous DRX.

  20. Dynamic recrystallization and texture development during hot deformation of a magnesium alloy AZ31

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.; Miura, H.; Sakai, T. [Univ. of Electro-Communications, Dept. of Mechanical Engineering and Intelligent Systems, Chofu, Tokyo (Japan)]. E-mail: Sakai@mce.uec.ac.jp

    2002-07-01

    Dynamic recrystallization (DRX) and texture development, taking place during hot deformation of a magnesium alloy AZ31 with a strong wire texture, was studied in compression at 673K (0.73T{sub m}). Two kinds of samples were machined parallel to the extruded and transverse direction of the Mg alloy rods. New fine grains are evolved at original grain boundaries corrugated at low strains and developed rapidly in the medium range of strain, finally leading to a roughly full evolution of equiaxial fine grains. Kink bands are evolved at grain boundaries corrugated and also frequently in grain interiors at low strains. The boundary misorientations of kink band increase rapidly with increasing strain and approach a saturation value in high strain. The average size of the regions fragmented by kink band is almost the same as that of new grains evolved in high strain. These characteristics of new grain evolution process are not changed by the orientation of the samples, while the flow behaviors clearly depend on it. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction, i.e. continuous dynamic recrystallization (DRX). The latter is discussed comparing with conventional, i.e. discontinuous, DRX. (author)

  1. Atmospheric corrosion of magnesium alloys AZ31 and AZ61 under continuous condensation conditions

    OpenAIRE

    Feliu Jr., S.; Maffiotte, C.; Galván Sierra, Juan Carlos; Barranco, Violeta

    2011-01-01

    This paper studies the corrosion rate of magnesium alloys AZ31 and AZ61 exposed in humid air under continuous condensation conditions. The shape of the gravimetric curves for corrosion progress suggests that the process is controlled by factors related with the corrosion product layer growing on the metallic surface according to gravimetric results there is an initial period in which only a small part of the corroded metal is incorporated in the corrosion product layer, but after longer testi...

  2. Resistance to corrosion of magnesium alloy AZ31 after plastic working

    OpenAIRE

    J. Przondziono; W. Walke; A. Szuła; Hadasik, E.; J. Szala; Wieczorek, J.

    2011-01-01

    The study presents results of electrochemical and chemical corrosion resistance tests of magnesium alloy AZ31 after plastic working. Electrochemical measurements were carried out in 1,35 % solution of NaCl. On the ground of registered polarisation curves, typical features characterising resistance to electrochemical corrosion, were determined. Resistance to chemical corrosion was tested by means of immersion in 3,5%solution of NaCl for the period of 1_5 days. By means of scanning electron mic...

  3. Evaluation of diffusion welding of 6061 aluminum and AZ31 magnesium alloys without using an interlayer

    International Nuclear Information System (INIS)

    Highlights: • Diffusion welding of Al to Mg alloys was performed without using an interlayer. • The voids were not observed at the interface because of the proper pressure. • The optimum bonding parameters involved T = 440 °C, P = 29 MPa and t = 60 min. • The bond strength at temperature of 440 °C was achieved as 42 MPa. • The hardness in the interfacial transition zone was increased by temperature rise. - Abstract: In this research, in order to join 6061 aluminum and AZ31 magnesium alloys without using an interlayer, the diffusion welding method was used. The tests were performed in temperature of 430–450 °C for 60 min and under pressure of 29 MPa in vacuum of 1 × 10−3 torr. Microstructural studies and determination of phase combinations in interfacial bonding were done by using of scanning electron microscopy (SEM). Mechanical properties of joints were measured by using a Vickers microhardness and shear strength. The results of studies have revealed a successful join between two alloys and confirmed the presence of different reaction layers in the diffusion zone. The chemical composition of these layers was determined by Energy-dispersive X-ray Spectroscopy (EDS). The formation of intermetallic compounds such as Al12Mg17 and Al3Mg2 was predicted by use of the phase diagram of aluminum–magnesium. According to the studies performed, interfacial transition zone (ITZ) with 23 and 27 μm thicknesses were formed respectively at 440 and 450 °C and the maximum amount of bond strength, 42 MPa, was achieved at 440 °C which was due to the suitable coalescence of metal surfaces

  4. XPS study of the surface chemistry on AZ31 and AZ91 magnesium alloys in dilute NaCl solution

    Science.gov (United States)

    Wang, Lei; Shinohara, Tadashi; Zhang, Bo-Ping

    2010-08-01

    The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH) 2 and MgCO 3 species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH) 2, MgO and MgCO 3 species was observed for both alloys. The presence of Al 3+ in the surface electrolyte to form Al 2O 3/Al(OH) 3 and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone.

  5. XPS study of the surface chemistry on AZ31 and AZ91 magnesium alloys in dilute NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lei [Materials Reliability Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shinohara, Tadashi, E-mail: SHINOHARA.Tadashi@nims.go.jp [Materials Reliability Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Zhang Boping [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2010-08-01

    The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH){sub 2} and MgCO{sub 3} species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH){sub 2}, MgO and MgCO{sub 3} species was observed for both alloys. The presence of Al{sup 3+} in the surface electrolyte to form Al{sub 2}O{sub 3}/Al(OH){sub 3} and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone.

  6. XPS study of the surface chemistry on AZ31 and AZ91 magnesium alloys in dilute NaCl solution

    International Nuclear Information System (INIS)

    The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH)2 and MgCO3 species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH)2, MgO and MgCO3 species was observed for both alloys. The presence of Al3+ in the surface electrolyte to form Al2O3/Al(OH)3 and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone.

  7. Characterization and degradation behavior of AZ31 alloy surface modified by bone-like hydroxyapatite for implant applications

    Science.gov (United States)

    Wen, Cuilian; Guan, Shaokang; Peng, Li; Ren, Chenxing; Wang, Xiang; Hu, Zhonghua

    2009-04-01

    Hydroxyapatite (HA) coating on AZ31 alloy substrate was prepared by a cathodic electrodeposition method. The as-deposited specimen was then post-treated with hot alkali solution to improve the corrosion resistance and bioactivity for implant applications. The microstructure and composition of HA coating, as well as its degradation behavior in simulated body fluid (SBF) were investigated. It reveals that the as-deposited coating consists of dicalcium phosphate dehydrate (DCPD, CaHPO 4·2H 2O) and HA. While 10 μm-thick nanowhisker HA coatings doped with Na +, Mg +, HPO 42-and CO 32- can be found after NaOH alkali treatment, which exhibits a very similar composition of natural bone. The post-treated coating was composed of needle-like particles with 1000 nm in length and 35 nm in diameter, having a slenderness ratio of about 28.6. Electrochemical tests shows that the Ecorr of Mg substrate significantly increased from -1.6 to -1.42 V after surface modified by HA coatings. There was obvious mass gain on post-treated specimen immersed in SBF during the first 30 days due to the Ca-P-Mg deposition. The HA-coated AZ31 alloy could slow down the degradation rate and effectively induce the deposition of Ca-P-Mg apatite in SBF, showing a good bioactivity.

  8. Effect of Thermal History on Microstructures and Mechanical Properties of AZ31 Magnesium Alloy Prepared by Friction Stir Processing

    Directory of Open Access Journals (Sweden)

    Fang Chai

    2014-02-01

    Full Text Available Hot-rolled AZ31 (Mg-2.57Al-0.84Zn-0.32Mn, in mass percentage magnesium alloy is subjected to friction stir processing in air (normal friction stir processing, NFSP and under water (submerged friction stir processing, SFSP. Thermal history of the two FSP procedures is measured, and its effect on microstructures and mechanical properties of the experimental materials is investigated. Compared with NFSP, the peak temperature during SFSP is lower and the duration time at a high temperature is shorter due to the enhanced cooling effect of water. Consequently, SFSP results in further grain refinement, and the average grain size of the NFSP and SFSP specimens in the stir zone (SZ are 2.9 μm and 1.3 μm, respectively. Transmission electron microscopy (TEM examinations confirm that grain refinement is attributed to continuous dynamic recrystallization both for NFSP and SFSP. The average Vickers hardness in the SZ of the NFSP and SFSP AZ31 magnesium alloy are 76 HV and 87 HV. Furthermore, the ultimate tensile strength and the elongation of the SFSP specimen increase from 191 MPa and 31.3% in the NFSP specimen to 210 MPa and 50.5%, respectively. Both the NFSP and SFSP alloys fail through ductile fracture, but the dimples are much more obvious in the SFSP alloy.

  9. Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    JIANG Jia; GODFREYB Andy; LIU Qing

    2009-01-01

    The evolution of the microstructure and texture with strain during compression at 150℃ of the mag-nesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) tech-nique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal <c+a> slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.AZ31, electron backscattered diffraction (EBSD), texture, slip, twinning.

  10. Nano grained AZ31 alloy achieved by equal channel angular rolling process

    International Nuclear Information System (INIS)

    Equal channel angular rolling (ECAR) is a severe plastic deformation process which is carried out on large, thin sheets. The grain size could be significantly decreased by this process. The main purpose of this study is to investigate the possibility of grain refinement of AZ31 magnesium alloy sheet by this process to nanometer. The effect of the number of ECAR passes on texture evolution of AZ31 magnesium alloy was investigated. ECAR temperature was controlled to maximize the grain refinement efficiency along with preventing cracking. The initial microstructure of as-received AZ31 sheet showed an average grain size of about 21 μm. The amount of grain refinement increased with increasing the pass number. After 10 passes of the process, significant grain refinement occurred and the field emission scanning electron microscopic (FESEM) micrographs showed that the size of grains were decreased significantly to about 14-70 nm. These grains were formed at the grain boundaries and inside some of the previous larger micrometer grains. Observation of optical microstructures and X-ray diffraction patterns (XRD) showed the formation of twins after ECAR process. Micro-hardness of material was studied at room temperature. There was a continuous enhancement of hardness by increasing the pass number of ECAR process. At the 8th pass, hardness values increased by 53%. At final passes hardness reduced slightly, which was attributed to saturation of strain in high number of passes.

  11. Stamping of Thin-Walled Structural Components with Magnesium Alloy AZ31 Sheets

    International Nuclear Information System (INIS)

    In the present study, the stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. In order to determine the proper forming temperature and set up a fracture criterion, tensile tests and forming limit tests were first conducted to obtain the mechanical behaviors of AZ31 sheets at various elevated temperatures. The mechanical properties of Z31 sheets obtained from the experiments were then adopted in the finite element analysis to investigate the effects of the process parameters on the formability of the stamping process of cell phone cases. The finite element simulation results revealed that both the fracture and wrinkle defects could not be eliminated at the same time by adjusting blank-holder force or blank size. A drawbead design was then performed using the finite element simulations to determine the size and the location of drawbead required to suppress the wrinkle defect. An optimum stamping process, including die geometry, forming temperature, and blank dimension, was then determined for manufacturing the cell phone cases. The finite element analysis was validated by the good agreement between the simulation results and the experimental data. It confirms that the cell phone cases can be produced with magnesium alloy AZ31 sheet by the stamping process at elevated temperatures

  12. Microstructure Evolutions during the Hot Extrusion Process of AZ 31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Luoxing

    2009-01-01

    The hot bulk deformation processes (such as extrusion, forging and rolling) are efficient ways to produce fine microstmcture. The effects of extrusion parameters on the evolved microstructure of directly extruded AZ 31B magnesium alloy were investigated. Extrusion processes were carried out at five different combinations with ram speed ranging from 2 to 8 mm·s-1 and billet temperature ranging from 350 to 450 ℃. The experimental results show that the peak extrusion force decreases with increase in billet temperature and decreases in ram speed. During all the extrusion the profile temperature and die temperature rise continuously. Small particles of secondary phase (β-Mg17A112) are uniformly distributed near the edge of the extruded profiles whereas their distribution is nonuniform in the centre of the extrudates. The size of secondary phase particles present in the central region of the specimens was found to increase with billet temperature and extrusion speed. All the specimens showed mixed microstructure-In the central region of the specimen, low volume fraction of dynamically recrystallized fine grains presented at the grain boundaries of original coarse grains; but near the edge region, the microstructure consisted nearly equiaxed free reerystallized grains.

  13. Analysis of metallic traces from the biodegradation of endomedullary AZ31 alloy temporary implants in rat organs after long implantation times.

    Science.gov (United States)

    Bodelón, O G; Iglesias, C; Garrido, J; Clemente, C; Garcia-Alonso, M C; Escudero, M L

    2015-08-01

    AZ31 alloy has been tested as a biodegradable material in the form of endomedullary implants in female Wistar rat femurs. In order to evaluate the accumulation of potentially toxic elements from the biodegradation of the implant, magnesium (Mg), aluminium (Al), zinc (Zn), manganese (Mn) and fluorine (F) levels have been measured in different organs such as kidneys, liver, lungs, spleen and brain. Several factors that may influence accumulation have been taken into account: how long the implant has been in place, whether or not the bone is fractured, and the presence of an MgF2 protective coating on the implant. The main conclusions and the clinical relevance of the study have been that AZ31 endomedullary implants have a degradation rate of about 60% after 13 months, which is fully compatible with fracture consolidation. Neither bone fracture nor an MgF2 coating seems to influence the accumulation of trace elements in the studied organs. Aluminium is the only alloying element in this study that requires special attention. The increase in Al recovered from the sampled organs represents 3.95% of the amount contained in the AZ31 implant. Al accumulates in a statistically significant way in all the organs except the brain. All of this suggests that in long-term tests AZ31 may be a suitable material for osteosynthesis. PMID:26238295

  14. Effect of rolling temperature of the magnesium alloy AZ31B formability; Efeito da temperatura de laminacao na deformabilidade da liga de magnesio AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Catorceno, L.L.C.; Zimmermann, A.J.O.; Padilha, A.F., E-mail: litzy.catorceno@poli.usp.b [Universidade de Sao Paulo (DEMM/EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica e de Materiais

    2010-07-01

    The magnesium alloy AZ31B presents an interesting set of properties, which makes it potential candidate for applications in automotive and aeronautics. The main limitation of magnesium alloys is the low capacity of plastic forming at room temperature. The main motivation of this project is to understand and control the microstructure and crystallographic texture of magnesium alloys, to improve their formability. The effect of rolling temperature on the formability of the alloy was studied in this stage of the project. The alloy in the form of annealed and recrystallized sheets (2 mm thick) was deformed by rolling at four different temperatures: 25, 100, 200 and 250 deg C. The microstructural characterization was achieved using several complementary techniques of microstructural analysis, such as optical microscopy, scanning electron microscopy, X-ray analysis by energy dispersive, X-ray diffraction and microhardness. Results about the effect of rolling temperature on the alloy formability were presented and discussed. (author)

  15. The analysis of the plastic deformation of two-layered magnesium – aluminium alloys (AZ31 – Al

    Directory of Open Access Journals (Sweden)

    R. Mola

    2016-10-01

    Full Text Available The paper presents the results of physical modelling of the plastic deformation of the two-layered AZ31 - Al alloys. The AZ31 - Al feedstock was produced using the diffusion bonding method. Heating under pressure led to the formation of a continuous layer of the intermetallic phases at the bond interface of AZ31 - Al. A compression test was used to determine the plastic deformation of the two-layered AZ31 - Al alloys. Based on the analysis of the investigation results it has been found that, as the strain rate decreases and temperature increases, the intermetallic phase yields, and a distinct thinning of the intermetallic phase layer has occurred in the zone directly affected by the anvil.

  16. Preliminary research on a novel bioactive silicon doped calcium phosphate coating on AZ31 magnesium alloy via electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xun [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Wan, Peng, E-mail: pwan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Tan, LiLi [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Fan, XinMin [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Ke [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China)

    2014-03-01

    A silicon doped calcium phosphate coating was obtained successfully on AZ31 alloy substrate via pulse electrodeposition. A novel dual-layer structure was observed with a porous lamellar-like and outer block-like apatite layer. In vitro immersion tests were adopted in simulated body fluid within 28 days of immersion. Slow degradation rate obtained from weight loss was observed for the Si-doped Ca–P coating, which was also consistent with the results of electrochemical experiments showing an enhanced corrosion resistance for the coating. Further formation of an apatite-like layer on the surface after immersion proved better integrity and biomineralization performance of the coating. Biological characterization was carried out for viability, proliferation and differentiation of MG63 osteoblast-like cells. The coating showed a good cell growth and an enhanced cell proliferation. Moreover, an increased activity of osteogenic marker ALP was found. All the results demonstrated that the Si-doped calcium phosphate was perspective to be used as a coating for magnesium alloy implants to control the degradation rate and enhance the bioactivity, which would facilitate the rapidity of bone tissue repair. - Highlights: • A Si-doped calcium phosphate coating was achieved via pulse ED on AZ31 alloy. • The coating was composed of a porous lamellar-like layer and outer block-like apatite. • The coating showed slow degradation rate and better biomineralization property. • The coating improved cell proliferation and activity of osteogenic marker ALP.

  17. Preliminary research on a novel bioactive silicon doped calcium phosphate coating on AZ31 magnesium alloy via electrodeposition

    International Nuclear Information System (INIS)

    A silicon doped calcium phosphate coating was obtained successfully on AZ31 alloy substrate via pulse electrodeposition. A novel dual-layer structure was observed with a porous lamellar-like and outer block-like apatite layer. In vitro immersion tests were adopted in simulated body fluid within 28 days of immersion. Slow degradation rate obtained from weight loss was observed for the Si-doped Ca–P coating, which was also consistent with the results of electrochemical experiments showing an enhanced corrosion resistance for the coating. Further formation of an apatite-like layer on the surface after immersion proved better integrity and biomineralization performance of the coating. Biological characterization was carried out for viability, proliferation and differentiation of MG63 osteoblast-like cells. The coating showed a good cell growth and an enhanced cell proliferation. Moreover, an increased activity of osteogenic marker ALP was found. All the results demonstrated that the Si-doped calcium phosphate was perspective to be used as a coating for magnesium alloy implants to control the degradation rate and enhance the bioactivity, which would facilitate the rapidity of bone tissue repair. - Highlights: • A Si-doped calcium phosphate coating was achieved via pulse ED on AZ31 alloy. • The coating was composed of a porous lamellar-like layer and outer block-like apatite. • The coating showed slow degradation rate and better biomineralization property. • The coating improved cell proliferation and activity of osteogenic marker ALP

  18. Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

    International Nuclear Information System (INIS)

    Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

  19. Structure and plasticity of the AZ31 magnesium alloy after hot deformation

    Directory of Open Access Journals (Sweden)

    D. Kuc

    2008-03-01

    Full Text Available Purpose: The favourable properties of magnesium account for the fact that it is applied not only in cast structural components but also in those subjected to plastic working. Currently, intensive works are conducted to optimize the processes of plastic working of these alloys The following work concentrates on the analysis of microstructure and plasticity of magnesium alloy AZ31 type during hot plastic deformation process.Design/methodology/approach: After rolling and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 200 to 450°C at 0.01 and 1.0 s-1 strain rates. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. Structural examination was carried out using light microscopy.Findings: The processes of structural reconstruction such as dynamic recrystallization, which take place during hot - deformation, have been detected.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated AZ31 type alloy. The results will constitute the basis for modelling the structural changes.Originality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated Fe3Al-5Cr alloy.

  20. Research on the drawing process with a large total deformation wires of AZ31 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bajor, T; Muskalski, Z; Suliga, M, E-mail: tbajor@wip.pcz.p [Czestochowa University of Technology, Faculty of Materials Processing Technology and Applied Physics, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland)

    2010-07-01

    Magnesium and their alloys have been extensively studied in recent years, not only because of their potential applications as light-weight engineering materials, but also owing to their biodegradability. Due to their hexagonal close-packed crystallographic structure, cold plastic processing of magnesium alloys is difficult. The preliminary researches carried out by the authors have indicated that the application of the KOBO method, based on the effect of cyclic strain path change, for the deformation of magnesium alloys, provides the possibility of obtaining a fine-grained structure material to be used for further cold plastic processing with large total deformation. The main purpose of this work is to present research findings concerning a detailed analysis of mechanical properties and changes occurring in the structure of AZ31 alloy wire during the multistage cold drawing process. The appropriate selection of drawing parameters and the application of multistep heat treatment operations enable the deformation of the AZ31 alloy in the cold drawing process with a total draft of about 90%.

  1. Effect of rolling temperature of the magnesium alloy AZ31B formability

    International Nuclear Information System (INIS)

    The magnesium alloy AZ31B presents an interesting set of properties, which makes it potential candidate for applications in automotive and aeronautics. The main limitation of magnesium alloys is the low capacity of plastic forming at room temperature. The main motivation of this project is to understand and control the microstructure and crystallographic texture of magnesium alloys, to improve their formability. The effect of rolling temperature on the formability of the alloy was studied in this stage of the project. The alloy in the form of annealed and recrystallized sheets (2 mm thick) was deformed by rolling at four different temperatures: 25, 100, 200 and 250 deg C. The microstructural characterization was achieved using several complementary techniques of microstructural analysis, such as optical microscopy, scanning electron microscopy, X-ray analysis by energy dispersive, X-ray diffraction and microhardness. Results about the effect of rolling temperature on the alloy formability were presented and discussed. (author)

  2. Hybrid laser-TIG welding, laser beam welding and gas tungsten arc welding of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Welding of AZ31B magnesium alloy was carried out using hybrid laser-TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW. Besides, the penetration of LATIG doubles that of TIG, and was four times that of LBW. In addition, arc stability was improved in hybrid of laser-TIG welding compared with using the TIG welding alone, especially at high welding speed and under low TIG current. It was found that the heat affect zone of joint was only observed in TIG welding, and the size of grains in it was evidently coarse. In fusion zone, the equiaxed grains exist, whose size was the smallest welded by LBW, and was the largest by TIG welding. It was also found that Mg concentration of the fusion zone was lower than that of the base one by EPMA in three welding processes

  3. Effects of benzotriazole on anodized film formed on AZ31B magnesium alloy in environmental-friendly electrolyte

    International Nuclear Information System (INIS)

    An environmental-friendly electrolyte of silicate and borate, which contained an addition agent of 1H-benzotriazole (BTA) with low toxicity (LD50 of 965 mg/kg), was used to prepare an anodized film on AZ31B magnesium alloy under the constant current density of 1.5 A/dm2 at room temperature. Effects of BTA on the properties of the anodized film were studied by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), loss weight measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results demonstrated that anodized growth process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependant on the BTA concentration, which might be attributed to the formation of an BTA adsorption layer on magnesium substrate surface. When the BTA concentration was 5 g/L in the electrolyte, a compact and thick anodized film could provide excellent corrosion resistance for AZ31B magnesium alloy.

  4. Quantitative Analysis of Composition Change in AZ31 Magnesium Alloy Using CF-LIBS After Laser Material Processing

    Science.gov (United States)

    Zhu, Dehua; Cao, Yu; Zhong, Rong; Chen, Xiaojing

    2015-11-01

    The concentration of elements in molten metal of AZ31 magnesium alloy after long pulsed Nd:YAG laser processing was quantitatively analyzed by using calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The composition change in AZ31 magnesium alloy under different laser pulse width was also investigated. The experimental results showed that CF-LIBS can obtain satisfactory quantitative or semi-quantitative results for matrix or major elements, while only qualitative analysis was possible for minor or trace elements. Moreover, it is found that the chemical composition of molten metal will change after laser processing. The concentration of magnesium in molten metal is lower than that present in the base metal. The Mg loss increases with an increase of pulse width in the laser processing. This result shows that the selective vaporization of different elements is affected by the pulse width during laser processing. supported by National Natural Science Foundation of China (Nos. 61405147, 51375348) and the Scientific Research Fund of Zhejiang Provincial Education Department, China (No. Y201430387)

  5. A novel simple strategy for in situ deposition of apatite layer on AZ31B magnesium alloy for bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Mousa, Hamouda M. [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley University, Qena 83523 (Egypt); Lee, Do Hee [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Park, Chan Hee, E-mail: biochan@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2015-10-01

    Graphical abstract: - Highlights: • Anodizing process was used for the surface modification of AZ31B magnesium alloy. • An appetite-like film was deposited on the surface of AZ31B magnesium alloy. • Ceramic film was investigated by XRD and XPS. • Nano-plates growth are observed though the implemented experimental design. • Significant increase in the substrate hardness and surface roughness was observed. - Abstract: In this study, for the first time, the degradation performance of AZ31B Mg alloy was tuned by an in situ deposition of apatite thin layer within a short time in one step. Using Taguchi method for experimental design, anodization process was designed under control conditions (time and voltage), and simulated body fluid (SBF) was used as the electrolyte to nucleate apatite-like compounds. The coated alloy was characterized through field emission scanning electron microscopy (FE-SEM), EDS, X-ray diffraction and XPS analysis. The results show that the applied voltage has a significant effect on the formation of apatite-like layers. Compared to the uncoated samples, microhardness and surface roughness of the coated samples showed remarkably different values. The potentiodynamic polarization results demonstrate that the polarization resistance of the anodized samples is higher than the substrate polarization resistance, thus improving the alloy corrosion resistant. Based on the experimental results, the proposed nanostructure apatite-like coating can offer a promising way to improve the biocompatibility and degradability properties of the Mg alloy for bone tissue regeneration.

  6. A novel simple strategy for in situ deposition of apatite layer on AZ31B magnesium alloy for bone tissue regeneration

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Anodizing process was used for the surface modification of AZ31B magnesium alloy. • An appetite-like film was deposited on the surface of AZ31B magnesium alloy. • Ceramic film was investigated by XRD and XPS. • Nano-plates growth are observed though the implemented experimental design. • Significant increase in the substrate hardness and surface roughness was observed. - Abstract: In this study, for the first time, the degradation performance of AZ31B Mg alloy was tuned by an in situ deposition of apatite thin layer within a short time in one step. Using Taguchi method for experimental design, anodization process was designed under control conditions (time and voltage), and simulated body fluid (SBF) was used as the electrolyte to nucleate apatite-like compounds. The coated alloy was characterized through field emission scanning electron microscopy (FE-SEM), EDS, X-ray diffraction and XPS analysis. The results show that the applied voltage has a significant effect on the formation of apatite-like layers. Compared to the uncoated samples, microhardness and surface roughness of the coated samples showed remarkably different values. The potentiodynamic polarization results demonstrate that the polarization resistance of the anodized samples is higher than the substrate polarization resistance, thus improving the alloy corrosion resistant. Based on the experimental results, the proposed nanostructure apatite-like coating can offer a promising way to improve the biocompatibility and degradability properties of the Mg alloy for bone tissue regeneration

  7. Effect of temperature on mechanical behavior of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    TAN Cheng-wen; XU Shan-na; WANG Lu; CHEN Zhi-yong; WANG Fu-chi; CAI Hong-nian

    2007-01-01

    Strain rate sensitivity and tension/compression asymmetry of AZ31 magnesium alloy at different temperatures and strain rates were investigated. Both of mechanical behaviors are temperature dependent. Strain rate sensitivity increases with increasing temperature. Thermally activated slip is the source of strain rate sensitivity. At the temperature below or near 373 K, strain rate sensitivity is very little. Tension/compression asymmetry in yielding decreases with increasing temperature. Twinning is the reason of tension/compression asymmetry. At the temperature above or near 573 K, the material shows little tension/compression asymmetry of the flow stress.

  8. Microstructure and texture evolution in multi-pass warm rolled AZ31 magnesium alloy

    OpenAIRE

    Liu Di; Liu Zuyan

    2015-01-01

    Electron Backscatter Diffraction (EBSD) is employed to characterize the microstructure and texture established during the process of warm rolled AZ31 magnesium alloy sheets. The grain size was refined from 17.4 μm to 3.8 μm after 4 pass rolling. Texture of as-rolled sheets was expressed by (0002) basal texture, and the texture intensity was increased with the rolling pass increasing. The mechanical properties of as-rolled sheets were greatly improved by warm rolling.

  9. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-07-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  10. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-06-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  11. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, S., E-mail: sfeliu@cenim.csic.es; Llorente, I.

    2015-08-30

    Highlights: • Surface chemistry of the corrosion product layers on magnesium alloys. • Influence of the type of alloy on the carbonate surface enrichment. • Relation between surface composition and protection properties. - Abstract: This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS.

  12. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    International Nuclear Information System (INIS)

    Highlights: • Surface chemistry of the corrosion product layers on magnesium alloys. • Influence of the type of alloy on the carbonate surface enrichment. • Relation between surface composition and protection properties. - Abstract: This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS

  13. Influence of post-weld hot rolling on the microstructure and mechanical properties of AZ31 magnesium alloy sheet

    International Nuclear Information System (INIS)

    The as-rolled AZ31 Mg alloy sheet was welded by double-sided tungsten inert gas (TIG) welding, followed by annealing and hot rolling with different reduction. The influence of the rolling reduction on the microstructure, tensile properties and microhardness of the specimens was examined. Results showed that the microstructure of the weld fusion zone (FZ) and heat affected zone (HAZ) became more and more consistent with that of the base metal (BM) as the hot rolling reduction increased. The β-Mg17Al12 phases in the FZ dissolved gradually during hot rolling. Both the weld joint and BM were strengthened by hot rolling; the tensile strength of weld joint and BM were closest when the rolling reduction was 27%. The microhardness of the welded sheet increased with rolling reduction

  14. Deformation behaviors of magnesium alloy AZ31 sheet in cold deep drawing

    Institute of Scientific and Technical Information of China (English)

    YANG Lian-fa; MORI Ken-ichiro; TSUJI Hirokazu

    2008-01-01

    To investigate how the popular magnesium alloy AZ31 sheet (aluminum 3%, zinc 1%) behaves in cold working, deep drawing experiments at room temperature, along with finite element(FE) simulation,were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions. The activities were focused on the fracture pattern, limit drawing ratio(LDR), deformation load, thickness distribution, anisotropic effect, as well as the influences of the annealing conditions and tool configuration on them. The results display that punch shoulder radius instead of die clearance, has much influence on the thickness distribution. The anisotropy is remarkable in cold working, which adversely impacts the LDR. The fracture often happens on the side wall at an angle to axis of the deformed specimen. The results also imply that the LDR for the material under present experimental conditions is 1.72, and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.

  15. Improving the fatigue property of welded joints for AZ31 magnesium alloy by ultrasonic peening treatment

    Institute of Scientific and Technical Information of China (English)

    Zhang Jinwang; Wang Wenxian; Zhang Lan; Mu Wei; Xu Bingshe

    2008-01-01

    The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment (UPT) was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20.0 MPa and 17.2 MPa at 2×106 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30.3 MPa and 24.7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2.74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40.0 MPa.

  16. Theoretical and Experimental Research on Forge Rolling Process of Preforms From Magnesium Alloy AZ31

    Directory of Open Access Journals (Sweden)

    Bulzak T.

    2015-04-01

    Full Text Available This paper presents results of theoretical and experimental research works on the rolling process of a lever preform from magnesium alloy AZ31. The forge rolling process of the preform was realized in the system oval-circle. The paper focuses mainly on kinematics of material flow and proper filling of rolling impressions. Research aiming at determining possibilities of faults presence in the form of cracks, overlapping and improper filling of the impressions were also conducted. During experimental research it was noticed that material cracking took place at the moment of material clamping by rolls. Moreover, it was stated that this cracking may be the result of large shearing stresses action, appearing at the moment of material clamping by rolls. Shearing stresses values were determined on the basis of numerical calculations. Next, tools were modified in order to lower tangential stresses at the moment of material clamping by rolls. The further experimental research with modified tools confirmed the rightness of the assumptions. On the basis of conducted works on the forge rolling process of magnesium alloy AZ31, it was stated that when material is clamped by tools tangential stresses intensification should not take place.

  17. Study on hot deformation behavior and microstructure evolution of cast-extruded AZ31B magnesium alloy and nanocomposite using processing map

    International Nuclear Information System (INIS)

    Highlights: ► Hot deformation behavior of AZ31B Mg alloy and nanocomposite were studied. ► Activation energy of AZ31B Mg alloy and nanocomposite were determined. ► Twining, shear bands and flow localization were observed. - Abstract: The hot deformation behavior and microstructural evolution of cast-extruded AZ31B magnesium alloy and nanocomposite have been studied using processing-maps. Compression tests were conducted in the temperature range of 250–400 °C and strain rate range of 0.01–1.0 s−1. The three-dimensional (3D) processing maps developed in this work, describe the variations of the efficiency of power dissipation and flow instability domains in the strain rate (ε) and temperature (T) space. The deformation mechanisms namely dynamic recrystallization (DRX), dynamic recovery (DRY) and instability regions were identified using processing maps. The deformation mechanisms were also correlated with transmission electron microscopy (TEM) and optical microscopy (OM). The optimal region for hot working has been observed at a strain rate (ε) of 0.01 s−1 and the temperature (T) of 400 °C for both magnesium alloy and nanocomposite. Few instability regimes have been identified in this study at higher strain rate (ε) and temperature (T). The stability domains have been identified in the lower strain rate regimes

  18. Effect of filler wire on the joint properties of AZ31 magnesium alloys using CO2 laser welding

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun

    2007-01-01

    Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that the weld appearance can be effectively improved when using laser welding with filler wire. The microhardness and tensile strength of joints are almost the same as those of the base metal when ER AZ31 or ER AZ61 wire is adopted. However, when the filler wire of ER 5356 aluminum alloy is used, the mechanical properties of joints become worse. For ER AZ31 and ER AZ61 filler wires, the microstructure of weld zone shows small dendrite grains. In comparison, for ER 5356 filler wire, the weld shows a structure of snowy dendrites and many intermetallic compounds and eutectic phases distribute in the dendrites. These intermetallic constituents with low melting point increase the tendency of hot crack and result in fragile joint properties. Therefore, ER AZ31 and ER AZ61 wire are more suitable filler material than ER 5356 for CO2 laser welding of AZ31 magnesium alloys.

  19. Numerical analysis of self-pierce riveting of AZ31 magnesium alloy sheets

    Science.gov (United States)

    Han, S. L.; Wu, Y. W.; Zeng, Q. L.; Gao, Y.

    2013-05-01

    Magnesium alloy sheet has a broad development prospect for lightweight metal in automotive industry. Selfpierce Riveting (SPR) process is a suitable joining technology to fasten materials of different nature. This paper is concerned with the development of numerical models of the SPR process of AZ31 magnesium alloy sheet. Based on DEFORM-2D finite element software, a two-dimensional axisymmetric model has been built for the SPR process. Then the distribution of stress and strain, and the stroke-load curve are analyzed in the forming process of the riveting. After a 2D simulation of SPR process, the quality of riveted joint is evaluated in terms of joint cross-sectional shape. The results show a better understanding of mechanical properties of SPR joints of magnesium alloy sheets. As a sufficient interlock and bottom thickness leading to a reasonably good joint, the numerical simulation method plays a significant role to predict the final strength of the joint.

  20. Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys

    International Nuclear Information System (INIS)

    X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 deg. C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH)2 and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of MgO and Mg(OH)2. A linear relation between the amount of magnesium carbonate formed on the surface and the subsequent corrosion behaviour in the humid environment was found. The AZ80 alloy revealed the highest amount of magnesium carbonate in the air-formed film and the highest atmospheric corrosion resistance, even higher than the AZ91D alloy, indicating that aluminium distribution in the alloy microstructure influenced the amount of magnesium carbonate formed.

  1. Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, S. [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain)], E-mail: anpardo@quim.ucm.es; Merino, M.C. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040 Madrid (Spain); Coy, A.E.; Viejo, F.; Arrabal, R. [Corrosion and Protection Centre, School of Materials, University of Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD (United Kingdom)

    2009-01-15

    X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 deg. C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH){sub 2} and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of MgO and Mg(OH){sub 2}. A linear relation between the amount of magnesium carbonate formed on the surface and the subsequent corrosion behaviour in the humid environment was found. The AZ80 alloy revealed the highest amount of magnesium carbonate in the air-formed film and the highest atmospheric corrosion resistance, even higher than the AZ91D alloy, indicating that aluminium distribution in the alloy microstructure influenced the amount of magnesium carbonate formed.

  2. Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys

    Science.gov (United States)

    Feliu, S., Jr.; Pardo, A.; Merino, M. C.; Coy, A. E.; Viejo, F.; Arrabal, R.

    2009-01-01

    X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 °C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH) 2 and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of MgO and Mg(OH) 2. A linear relation between the amount of magnesium carbonate formed on the surface and the subsequent corrosion behaviour in the humid environment was found. The AZ80 alloy revealed the highest amount of magnesium carbonate in the air-formed film and the highest atmospheric corrosion resistance, even higher than the AZ91D alloy, indicating that aluminium distribution in the alloy microstructure influenced the amount of magnesium carbonate formed.

  3. Microstructural evolution during the annealing of an extruded AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Research highlights: The manuscript presents an experimental investigation on the microstructure and texture development during a post-extrusion heat treatment of an AZ31 alloy, by using neutron as well as electron diffraction techniques. The results show clearly the texture changes from the fibre to the fibre component with grain growth and the role of internal misorientation as an important driving force for the grain growth. The preferred growth of the grains having the fibre component leads to a transition of the main texture component to the corresponding global texture. - Abstract: Microstructural evolution during the annealing of AZ31 extruded rod at 400 oC has been examined by employing neutron diffraction and electron backscatter diffraction (EBSD). In the as-extruded bar, equiaxed grains smaller than 5 μm and large elongated grains having significant degrees of internal misorientation are oriented mainly with parallel to the extrusion direction. Rapid grain growth occurs within the 180 s annealing period at 400 oC at the expense of the small grains with the internal orientation gradient as driving force. After short time annealing, small equiaxed grains are formed inside the large elongated grains, and grains having parallel to the extrusion direction show preferred growth. As a result, a transition of the main texture component to the component occurs after annealing for 1800 s at 400 oC.

  4. Corrosion of magnesium alloy AZ31 screws is dependent on the implantation site

    Energy Technology Data Exchange (ETDEWEB)

    Willbold, E. [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany); Kaya, A.A. [Mugla University, Engineering Faculty, Metallurgy and Materials Engineering Department, Mugla (Turkey); Kaya, R.A. [MedicalPark Hospital, Kueltuer Sok No:1, 34160 Bahcelievler, Istanbul (Turkey); Beckmann, F. [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str.1, D - 21502 Geesthacht (Germany); Witte, F., E-mail: witte.frank@mh-hannover.de [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany)

    2011-12-15

    The corrosion of biodegradable materials is a crucial issue in implant development. Among other materials, magnesium and magnesium based alloys are one of the most promising candidates. Since the corrosion of biodegradable materials depends on different physiological parameters like pH or ion concentrations, the corrosion might be different in different biological environments. To investigate this issue, we produced screws from magnesium alloy AZ31 and implanted them into the hip bone of 14 sheep. After 3 and 6 months, the screws were explanted and analyzed with synchrotron-radiation based micro-computed tomography and hard tissue histology. We found considerable differences in the corrosion behavior of the magnesium screws with respect to its original tissue location. However, we could detect a normal immunological tissue response.

  5. CO2 and diode laser welding of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Magnesium alloys are being increasingly used in automotive and aerospace structures. Laser welding is an important joining method in such applications. There are several kinds of industrial lasers available at present, including the conventional CO2 and Nd:YAG lasers as well as recently available high power diode lasers. A 1.5 kW diode laser and a 2 kW CO2 laser are used in the present study for the welding of AZ31 alloys. It is found that different welding modes exist, i.e., keyhole welding with the CO2 laser and conduction welding with both the CO2 and the diode lasers. This paper characterizes welds in both welding modes. The effect of beam spot size on the weld quality is analyzed. The laser processing parameters are optimized to obtain welds with minimum defects

  6. Grain size and texture changes of magnesium alloy AZ31 during multi-directional forging

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Grain size and texture changes of magnesium alloy AZ31 were studied in multidirectional forging(MDF) under decreasing temperature conditions. MDF was carried out up to large cumulative strains of 4.8 with changing the loading direction during decrease in temperature from pass to pass. MDF can accelerate the uniform development of fine-grained structures and increase the plastic workability at low temperatures. As a result, the MDFed alloy shows excellent higher strength as well as moderate ductility at room temperature even at the grain size below 1 μm. Superplastic flow takes place at 423 K and depends on the anisotropy of MDFed samples. The mechanisms of strain-induced free-grained structure development and of the plastic deformation were discussed in detail.

  7. Corrosion of magnesium alloy AZ31 screws is dependent on the implantation site

    International Nuclear Information System (INIS)

    The corrosion of biodegradable materials is a crucial issue in implant development. Among other materials, magnesium and magnesium based alloys are one of the most promising candidates. Since the corrosion of biodegradable materials depends on different physiological parameters like pH or ion concentrations, the corrosion might be different in different biological environments. To investigate this issue, we produced screws from magnesium alloy AZ31 and implanted them into the hip bone of 14 sheep. After 3 and 6 months, the screws were explanted and analyzed with synchrotron-radiation based micro-computed tomography and hard tissue histology. We found considerable differences in the corrosion behavior of the magnesium screws with respect to its original tissue location. However, we could detect a normal immunological tissue response.

  8. Formation of Ha-Containing Coating on AZ31 Magnesium Alloy by Micro-Arc Oxidation

    Science.gov (United States)

    Tang, Hui; Li, Deyu; Chen, Xiuping; Wu, Chao; Wang, Fuping

    2013-08-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this study, a HA-containing coating was fabricated by micro-arc oxidation (MAO). The active plasma species of micro-discharge was studied by optical emission spectroscopy (OES). The microstructure and composition were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion behavior and apatite-forming ability were studied by electrochemical tests and immersed samples in simulated body fluids (SBF). The results show that the microdischarge channel model is gas discharges and oxide layer discharges. The elements from the substrate and electrolyte take part in the formation of the coating. The MAO coating significantly improves the corrosion resistance of AZ31 magnesium alloy and enhances the apatite formation ability.

  9. Effect of Mucin and Bicarbonate Ion on Corrosion Behavior of AZ31 Magnesium Alloy for Airway Stents

    Directory of Open Access Journals (Sweden)

    Yongseok Jang

    2014-08-01

    Full Text Available The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO3− and mucin in Gamble’s solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX and X-ray diffraction (XRD. Electrochemical impedance spectroscopy (EIS was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble’s solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.

  10. Corrosion mechanism of micro-arc oxidation treated biocompatible AZ31 magnesium alloy in simulated body fluid

    Institute of Scientific and Technical Information of China (English)

    Ying Lia; Fang Lu; Honglong Li; Wenjun Zhu; Haobo Pan; Guoxin Tand; Yonghua Lao; Chengyun Ning; Guoxin Ni

    2014-01-01

    The rapid degradation of magnesium (Mg) based alloys has prevented their further use in orthopedic trauma fixation and vascular intervention, and therefore it is essential to investigate the corrosion mechanism for improving the corrosion resistance of these alloys. In this work, the effect of applied voltage on the surface morphology and the corrosion behavior of micro-arc oxidation (MAO) with different voltages were carried out to obtain biocompatible ceramic coatings on AZ31 Mg alloy. The effects of applied voltage on the surface morphology and the corrosion behavior of MAO samples in the simulated body fluid (SBF) were studied systematically. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were employed to characterize the morphologies and phase compositions of coating before and after corrosion. The results showed that corrosion resistance of the MAO coating obtained at 250 V was better than the others in SBF. The dense layer of MAO coating and the corrosion precipitation were the key factors for corrosion behavior. The corrosion of precipitation Mg(OH)2 and the calcium phosphate (Ca–P) minerals on the surface of MAO coatings could enhance their corrosion resistance effectively. In addition, the mechanism of MAO coated Mg alloys was proposed.

  11. Effects of nano-particles strengthening activating flux on the microstructures and mechanical properties of TIG welded AZ31 magnesium alloy joints

    International Nuclear Information System (INIS)

    Highlights: • Increased nano-particles strengthening activating flux degraded TIGed seams. • The reaction between SiC particles and Mg alloy produced Al4C3 and Mg2Si phases. • Al4C3 and SiC particles promoted the nucleation and suppressed the growth of α-Mg. • Refined α-Mg grains, precipitated phase and SiC particles enhanced TIGed joints. - Abstract: In this paper, AZ31 magnesium alloy joints were processed by nano-particles strengthening activating flux tungsten inert gas (NSA-TIG) welding, which was achieved by the mixed TiO2 and nano-SiC particles coated on the samples before welding tests. The macro/micro structural observation and mechanical properties evaluation of the welding joints were conducted by using optical microscope, scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction and tension and microhardness tests. The results showed that nano-particles strengthening activating flux effective improved the microstructure, microhardness in fusion zone, ultimate tensile strength of the TIG welding joints. In addition, the chemical reaction between part of SiC particles and AZ31 magnesium alloy produced Al4C3 and Mg2Si in the joints. The Al4C3 performed as nucleating agents for α-Mg and the dispersed Mg2Si and SiC particles enhanced the mechanical properties of the NSA-TIG welding joints. However, large heat input induced by the increase of the surface coating density of the nano-particles strengthening activating flux, increased the α-Mg grain sizes and weakened the mechanical properties of the welded joints. Therefore, the grain size of α-Mg, distribution of β-Mg17Al12, Mg2Si and SiC particles together influenced the evolution of the mechanical properties of the NSA-TIG welded AZ31 magnesium alloy joints

  12. Lap shear strength and fatigue life of friction stir spot welded AZ31 magnesium and 5754 aluminum alloys

    International Nuclear Information System (INIS)

    Lightweighting is today considered as one of the key strategies in reducing fuel consumption and anthropogenic greenhouse gas emissions. The structural applications of lightweight magnesium and aluminum alloys in the transportation industry inevitably involve welding and joining while guaranteeing the safety and reliability of motor vehicles. This study was aimed at evaluating lap shear strength and fatigue properties of friction stir spot welded (FSSWed) AZ31B-H24 Mg and 5754-O Al alloys in three combinations, i.e., similar Mg-to-Mg, Al-to-Al, and dissimilar Al-to-Mg joints. The Mg/Mg similar weld had a nugget-shaped stir zone (SZ) around the keyhole where fine recrytallized equiaxed grains were observed. While the hardness profile of the Mg/Mg similar weld exhibited a W-shaped appearance, the lower hardness values appeared in the TMAZ and HAZ of both Mg/Mg and Al/Al similar welds. In the Al/Mg dissimilar weld, a characteristic interfacial layer consisting of intermetallic compounds (IMC) Al12Mg17 and Al3Mg2 was observed. Both Mg/Mg and Al/Al similar welds had significantly higher lap shear strength, failure energy and fatigue life than the Al/Mg dissimilar weld. While the Al/Al weld displayed a slightly lower lap shear strength than the Mg/Mg weld, the Al/Al weld had higher failure energy and fatigue life. Three types of failure modes were observed. In the Mg/Mg and Al/Al similar welds, at higher cyclic loads nugget pullout failure occurred due to fatigue crack propagation circumferentially around the nugget, while at lower cyclic loads fatigue failure occurred perpendicular to the loading direction caused by the opening of keyhole through crack initiation in the TMAZ and HAZ. In the Al/Mg dissimilar weld nugget debonding failure mode was observed because of the presence of an interfacial IMC layer.

  13. Combined effect of pulse electron beam treatment and thin hydroxyapatite film on mechanical features of biodegradable AZ31 magnesium alloy

    Science.gov (United States)

    Surmeneva, M. A.; Tyurin, A. I.; Teresov, A. D.; Koval, N. N.; Pirozhkova, T. S.; Shuvarin, I. A.; Surmenev, R. A.

    2015-11-01

    The morphology, elemental, phase composition, nanohardness, and Young's modulus of the hydroxyapatite (HA) coating deposited via radio frequency (RF) magnetron sputtering onto the AZ31 surface were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and nanoindentationtechniques. The calcium phosphate (Ca/P) molar ratio of the HA coating deposited via RF-magnetron sputtering onto AZ31 substrates according to EDX was 1.57+0.03. The SEM experiments revealed significant differences in the morphology of the HA film deposited on untreated and treated with the pulsed electron beam (PEB) AZ31 substrate. Nanoindentation studies demonstrated significant differences in the mechanical responses of the HA film deposited on the initial and PEB-modified AZ31 substrates. The nanoindentation hardness and the Young's modulus of the HA film on the magnesium alloy modified using the PEB treatment were higher than that of the HA layer on the untreated substrate. Moreover, the HA film fabricated onto the PEB-treated surface was more resistant to plastic deformation than the same film on the untreated AZ31 surface.

  14. Biofunctional composite coating architectures based on polycaprolactone and nanohydroxyapatite for controlled corrosion activity and enhanced biocompatibility of magnesium AZ31 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zomorodian, A., E-mail: amir.zomorodian@ist.utl.pt [ICEMS-DEQ, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Garcia, M.P. [Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of Porto, Porto (Portugal); Moura e Silva, T. [ICEMS-DEQ, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); ISEL, Department of Mechanical Engineering, 1959-007 Lisboa (Portugal); Fernandes, J.C.S. [ICEMS-DEQ, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Fernandes, M.H. [Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of Porto, Porto (Portugal); Montemor, M.F. [ICEMS-DEQ, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2015-03-01

    In this work a biofunctional composite coating architecture for controlled corrosion activity and enhanced cellular adhesion of AZ31 Mg alloys is proposed. The composite coating consists of a polycaprolactone (PCL) matrix modified with nanohydroxyapatite (HA) applied over a nanometric layer of polyetherimide (PEI). The protective properties of the coating were studied by electrochemical impedance spectroscopy (EIS), a non-disturbing technique, and the coating morphology was investigated by field emission scanning electron microscopy (FE-SEM). The results show that the composite coating protects the AZ31 substrate. The barrier properties of the coating can be optimized by changing the PCL concentration. The presence of nanohydroxyapatite particles influences the coating morphology and decreases the corrosion resistance. The biocompatibility was assessed by studying the response of osteoblastic cells on coated samples through resazurin assay, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The results show that the polycaprolactone to hydroxyapatite ratio affects the cell behavior and that the presence of hydroxyapatite induces high osteoblastic differentiation. - Highlights: • A biofunctional coating architecture for bioresorbable AZ31 Mg alloys is proposed. • The composite coating provides corrosion protection of the bare material. • The coating enhances alkaline phosphatase activity of osteoblastic cells. • The presence of hydroxyapatite results in higher osteoblastic differentiation.

  15. Biofunctional composite coating architectures based on polycaprolactone and nanohydroxyapatite for controlled corrosion activity and enhanced biocompatibility of magnesium AZ31 alloy

    International Nuclear Information System (INIS)

    In this work a biofunctional composite coating architecture for controlled corrosion activity and enhanced cellular adhesion of AZ31 Mg alloys is proposed. The composite coating consists of a polycaprolactone (PCL) matrix modified with nanohydroxyapatite (HA) applied over a nanometric layer of polyetherimide (PEI). The protective properties of the coating were studied by electrochemical impedance spectroscopy (EIS), a non-disturbing technique, and the coating morphology was investigated by field emission scanning electron microscopy (FE-SEM). The results show that the composite coating protects the AZ31 substrate. The barrier properties of the coating can be optimized by changing the PCL concentration. The presence of nanohydroxyapatite particles influences the coating morphology and decreases the corrosion resistance. The biocompatibility was assessed by studying the response of osteoblastic cells on coated samples through resazurin assay, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The results show that the polycaprolactone to hydroxyapatite ratio affects the cell behavior and that the presence of hydroxyapatite induces high osteoblastic differentiation. - Highlights: • A biofunctional coating architecture for bioresorbable AZ31 Mg alloys is proposed. • The composite coating provides corrosion protection of the bare material. • The coating enhances alkaline phosphatase activity of osteoblastic cells. • The presence of hydroxyapatite results in higher osteoblastic differentiation

  16. Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

    Science.gov (United States)

    Ying-hong, Peng; Qun-feng, Chang; Da-yong, Li; Xiao-qin, Zeng

    2007-05-01

    AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal - mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double-action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing depth of square parts of AZ31 magnesium alloy sheet.

  17. Application of Anand's constitutive model on twin roll casting process of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-dong; JU Dong-ying

    2006-01-01

    Twin-roll thin strip casting process combines casting and hot rolling into a single process,in which thermal stress and thermal mechanical stress were involved. Considering the high temperature gradient,the existing of liquid and solid regions and rolling deformation,suitable constitutive model is the key to describe the process. Anand's model is a temperature-dependent,rate-dependent and unified of creep and plasticity model and the Jaumann derivative was employed in Anand's model which makes the constitutive model frame-indifferent or objective,therefore the highly nonlinearities behavior in the twin-roll casting process can be simulated. The parameters of the Anand's model were regressed based on the compression tests of AZ31 magnesium alloy. The simulation results reveal that the Anand's model can well describe the deformation characteristics of twin-roll casting process. Based on the simulation results,the form of evolution equations in Anand's model was discussed.

  18. Metallurgical Evaluation of AZ31B-H24 Magnesium Alloy Friction Stir Welds

    Science.gov (United States)

    Pareek, M.; Polar, A.; Rumiche, F.; Indacochea, J. E.

    2007-10-01

    Friction Stir welding of 3.175 mm (0.125 in.) thick plates of AZ31-H24 magnesium alloy was performed using several travel velocities and tool-rotation speeds. After production the welds were cross-sectioned and a metallurgical characterization was performed using optical microscopy, and scanning electron microscopy. Assessment of the weld nugget or “stirred zone” shows evidence of dynamic recrystallization and the start of grain growth in some spots of this region compared to the parent metal. Recrystallization was identified in the thermomechanically affected zone (TAZ) as well. The mechanical properties of the weld are correlated with the corresponding microstructures present in the weld nugget and TMAZ. Corrosion resistance of the weld was assessed using Electrochemical Impedance Spectroscopy (EIS) techniques and immersion tests in a corrosive environment; it showed better corrosion resistance than the base metal.

  19. Fatigue and material characteristics of a hot-formed AZ31 magnesium alloy

    Science.gov (United States)

    Suh, Chang-Min; Hor, Kwang-Ho; Nahm, Seung-Hoon; Suh, Min-Soo

    2015-03-01

    Magnesium alloys are known to be hard-forming materials at room temperature owing to their material structure. This study analyzes the optimal temperature conditions of warm-forming and the forming process by using a high-pressure laminating test and FM analysis, respectively. The effect of temperatures on the fatigue limit was examined from the collected specimens by analyzing the material properties after the fatigue test. The material formed at a temperature of 230°C shows occasional defects, but the best forming quality was obtained at 270°C. The optimal temperature for the forming process was found to be 250°C considering the material quality and thermal efficiency. The overall fatigue life of specimens decreases with an increase in the processing temperature. The fatigue limit of AZ31 formed at 250°C was approximately 100 MPa after 106 cycles.

  20. Effect of driver roll rotational speed on hot ring rolling of AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Xiaodong Luo

    2014-06-01

    Full Text Available Based on the ABAQUS/Explicit code, A 3D elastic–plastic and coupled thermo-mechanical FE model of radial ring rolling of AZ31 Magnesium alloy has been proposed to analyze the influence of rotational speed of driver roll to study the inhomogeneity distribution of strain and temperature, fishtail coefficient, rolling force parameters. The results show that: (1 when the rotational speed of driver roll n increases, the strain distribution of the rolled ring becomes less homogeneous, and the temperature distribution more homogeneous yet, and leading to an optimal n value; (2 the fishtail coefficient firstly decreases, then increases with the increase of n; (3 the rolling force, contact area and rolling moment gradually descend with the increase of n.

  1. Microstructure, Textures and Deformation Behaviors of Fine-grained Magnesium Alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    Ping YANG; Zude ZHAO; Xueping REN; Shaodong HUANG

    2005-01-01

    Channel die compression and initial textures are used to activate different deformation mechanisms in a fine-grained magnesium alloy AZ31. The σ-ε curves, microstructures and, particularly, textures are analyzed to reveal different deformation mechanisms and to compare with those of coarse grained samples. Dominant double-prismatic slip,{1012} twinning and basal slip are detected in three types of samples, respectively, which is similar to those of coarse grained samples. The detrimental effect of shear band formation or {1011} twinning is limited in fine grained microstructure. In addition to the higher flow stress at low temperature an early decrease in flow stress at higher temperature is also found in fine-grained samples in comparison with their coarse-grained counterparts. This softening is ascribed to the early dynamic recrystallization or grain boundary glide.

  2. Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    GODFREYB; Andy

    2009-01-01

    The evolution of the microstructure and texture with strain during compression at 150℃ of the magnesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) technique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.

  3. Influence of initial textures on dynamic recrystallization and textures in AZ31 magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    YANG Ping(杨平); CUI Feng-e(崔凤娥); MA Shi-cai(马世才); G Gottstein

    2003-01-01

    Microscopy and X-ray diffractometry were applied to inspect the influence of initial texture on dynamic recrystallization and texture formation in AZ31 magnesium alloys during channel die compression. The results show that stress-strain curves, microstructures and textures depend on initial textures. Two types of nucleation sites are detected which are in different proportions depending on initial textures. Dynamic recrystallization proceeds faster in samples with more inhomogeneity. When the basal planes of grains are parallel to rolling plane of sample with scattering around transverse direction, no new texture component occurs and texture is strengthened together with dynamic recrystallization. By other initial textures there are texture changes during hot deformation. New grains rotate gradually to basal orientation at heavy strain.

  4. Effect of microalloying (Ca, Sr, and Ce) on elevated temperature tensile behavior of AZ31 magnesium sheet alloy

    International Nuclear Information System (INIS)

    Research highlights: → Hot tensile behavior of AZ31 sheet microalloyed with Ca, Sr and Ce was investigated. → Under superplastic conditions the formability is notably improved by microalloying. → Second phase particles resist grain coarsening and retard cavitations' development. → Under the high Z conditions the deformation is controlled by the dislocation creep. → Under the low Z conditions the deformation is controlled by grain boundary sliding. - Abstract: The effect of microalloying with calcium, strontium, and cerium on the microstructure and the elevated temperature deformation behavior of magnesium sheet alloy AZ31 was investigated. Base composition and microalloyed AZ31 materials were cast and rolled into wrought sheet by an identical thermo-mechanical process. A series of hot tensile tests (temperatures of 300 deg. C, 400 deg. C, and 450 deg. C; constant true strain rates of 0.1 s-1, 0.01 s-1, 0.001 s-1, and 0.0003 s-1) were performed to characterize the deformation behavior of the sheet alloys. Interrupted tensile tests were used to study microstructural evolution with strain. A well-dispersed and thermally stable second phase produced by microalloying refines, stabilizes the grain structure, and significantly enhances hot formability of AZ31 sheet. The enhancement is most pronounced under deformation conditions of 450 deg. C and; 0.0003 s-1 strain rate, with tensile elongation increasing from 347% for the base alloy, to 406% with Ca only, 437% with Ca and Ce, and 552% with Ca, Sr and Ce for microalloyed AZ31 alloys. The second phase particles resist grain coarsening, promote grain boundary sliding, retard strain localization or necking, and postpone cavitation to higher strain levels to achieve this improvement in formability.

  5. Development of surface composite based on Mg–Al–Ni system on AZ31 magnesium alloy and evaluation of formation mechanism

    International Nuclear Information System (INIS)

    Highlights: • This research showed that by applying friction stir processing (FSP) in-situ surface composite based on Mg–Al/Ni alloying systems is produced on AZ31 plate under different FSP passes. • Thermodynamic and kinetic study of interfacial solid state reactions confirmed phase formation during different FSP passes. • Moreover, the effective Gibbs free energy of formation graphs for the compounds were plotted at 711 K. • Based on kinetic standpoint, schematic diagram of Mg–Ni intermetallic compounds during difference FSP passes is plotted. • Due to presence of intermetallic phases the mean hardness of the stir zone reached about 106 Hv, which is about two times higher than the base metal. - Abstract: The in-situ synthesis of Mg–Al–Ni composite on the surface of AZ31 plate by friction stir processing (FSP), has been investigated in this article. The unprocessed AZ31 plate consisted of grains of 25 μm size. By increasing the number of FSP passes from one to five, the grain size of the AZ31 plate decreased to 7.5 and 3 μm, respectively. A uniform distribution of the reinforcements was also obtained by increasing the number of FSP passes. Based on the results of X-ray diffraction (XRD) and Energy dispersive spectrometry (EDS) analyses, Mg2Ni and Al3Ni2 intermetallic compounds are in-situ formed by a single-pass FSP of the composite specimens. By increasing the number of FSP passes, the amounts of Mg2Ni and Al3Ni2 compounds are dramatically reduced and AlNi and MgNi2 intermetallic compounds take their place. Thermodynamic and kinetic of interfacial solid state reactions were studied to determine the reactive mechanisms and phase evolutions during different passes of FSP. The maximum amount of hardness (∼106 Hv), was obtained for the composite sample after five passes of FSP

  6. Resistance spot weld fatigue behavior and dislocation substructures in two different heats of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, L.; Liu, L. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON M5B 2K3 (Canada); Esmaeili, S. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Zhou, Y., E-mail: nzhou@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1 (Canada)

    2011-11-25

    Highlights: {yields} AZ31 SA resistance spot welds with a refined fusion zone microstructure had a longer fatigue life than SB. {yields} Typical dislocation configurations in the coarse-grained SB welds were parallel dislocation lines produced by basal slip. {yields} Dislocation configurations in the fine-grained SA were elongated cells arising from basal and pyramidal multiple slips. {yields} Slip incompatibilities led to high stress that activated twinning in SB, while pyramidal slip and twinning in SA. {yields} An increase of the amount and dispersibility of slip systems contributed to the improvement of fatigue life in SA welds. - Abstract: Fatigue life and dislocation substructure were evaluated in two groups of AZ31 Mg alloy resistance spot welds (heats SA and SB respectively, which had similar chemical compositions but different fusion zone microstructures). The results showed that the SA welds with a refined microstructure displayed a higher fatigue resistance than the SB welds when tested under conditions of higher cyclic load range causing interfacial failure across the fusion zone. TEM examinations revealed that typical dislocation configurations in the coarse-grained SB welds were parallel dislocation lines and parallelogram dislocation cells produced by basal slip, while elongated dislocation cells arising from basal and pyramidal multiple slips occurred in the SA welds. Twinning was observed to occur in both SA and SB welds, with more twins present in the SB welds. The strong slip incompatibilities between adjacent dendritic grains led to high local stress concentrations that activated twinning in the coarse-grained SB welds, while pyramidal slip together with twinning occurred in the fine-grained SA welds. This resulted in increased number and dispersion of slip systems which improved fatigue life in the SA welds.

  7. Resistance spot weld fatigue behavior and dislocation substructures in two different heats of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: → AZ31 SA resistance spot welds with a refined fusion zone microstructure had a longer fatigue life than SB. → Typical dislocation configurations in the coarse-grained SB welds were parallel dislocation lines produced by basal slip. → Dislocation configurations in the fine-grained SA were elongated cells arising from basal and pyramidal multiple slips. → Slip incompatibilities led to high stress that activated twinning in SB, while pyramidal slip and twinning in SA. → An increase of the amount and dispersibility of slip systems contributed to the improvement of fatigue life in SA welds. - Abstract: Fatigue life and dislocation substructure were evaluated in two groups of AZ31 Mg alloy resistance spot welds (heats SA and SB respectively, which had similar chemical compositions but different fusion zone microstructures). The results showed that the SA welds with a refined microstructure displayed a higher fatigue resistance than the SB welds when tested under conditions of higher cyclic load range causing interfacial failure across the fusion zone. TEM examinations revealed that typical dislocation configurations in the coarse-grained SB welds were parallel dislocation lines and parallelogram dislocation cells produced by basal slip, while elongated dislocation cells arising from basal and pyramidal multiple slips occurred in the SA welds. Twinning was observed to occur in both SA and SB welds, with more twins present in the SB welds. The strong slip incompatibilities between adjacent dendritic grains led to high local stress concentrations that activated twinning in the coarse-grained SB welds, while pyramidal slip together with twinning occurred in the fine-grained SA welds. This resulted in increased number and dispersion of slip systems which improved fatigue life in the SA welds.

  8. Prediction of corrosion rate of AZ31B magnesium alloy under salt fog environment in NaCl solution

    OpenAIRE

    even">D.Thirumalaikumarasamy,; , K.Shanmugam and V. Balasubramanian

    2013-01-01

    Magnesium alloys have gained considerable interest as a material for automotive and aerospace applications due to its low density, high specific strength, and good castability. However, another considerable issue is their corrosion properties. This restricts their practical applications. In this present research, corrosion behavior of the AZ31B magnesium alloy was evaluated by conducting salt fog test in NaCl solution at different chloride ion concentrations, pH values, spraying times, and ai...

  9. Biodegradation behavior of micro-arc oxidized AZ31 magnesium alloys formed in two different electrolytes

    International Nuclear Information System (INIS)

    Highlights: ► Phosphate coating has lesser degradation rate than silicate coating in r-SBF solution. ► Farringtonite phase is chemically more stable than forsterite phase in SBF solution. ► Apatite forming ability of forsterite containing coating is better than farringtonite containing film. ► The hydrophilisity nature of silicate film on magnesium alloy with respect to its roughness, is greater than phosphate film. - Abstract: Degradation behavior of coated magnesium alloys is among most prominent factors for their biomedical applications. In this study, bio-corrosion behavior of micro-arc oxidized magnesium AZ31 alloys formed in silicate and phosphate baths was investigated in r-SBF medium. For this purpose polarization behavior and open circuit profile of the coated samples were achieved by electrochemical and immersion tests, respectively. Moreover, the morphology and composition of the coatings were evaluated before and after immersion test using scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The results showed that the phosphate film had better corrosion resistance and greater thickness than silicate film and, in turn, the lesser degradability in SBF solution, so that Ca2+ and PO43− containing compounds were more abundant on silicate film than phosphate film. Moreover phosphate film had greater surface roughness and lesser hydrophilic nature.

  10. The hot blow forming of AZ31 Mg sheet: Formability assessment and application development

    Science.gov (United States)

    Carter, Jon T.; Krajewski, Paul E.; Verma, Ravi

    2008-11-01

    The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General Motors Corporation is reviewed.

  11. Microstructure and properties of AZ31 magnesium alloy by continuous variable cross-section recycled extrusion%连续变断面循环挤压AZ31镁合金的组织与性能

    Institute of Scientific and Technical Information of China (English)

    刘长瑞; 任红霞; 王庆娟

    2009-01-01

    采用连续变断面循环挤压法分别对变形镁合金AZ31铸锭和商业AZ31进行不同循环道次的变形,考察其组织、性能变化.结果表明:AZ31镁合金铸锭经过一个循环的挤压,晶粒明显细化.商业AZ31铝合金材料分别进行2、4、6、8次循环变形,随着变形量增大,平均晶粒尺寸不断减小,组织趋于均匀;真应变为16时,平均晶粒尺寸为5.5 μm;随着循环次数增加,伸长率不断增加,与原始态的相比可提高2倍左右,但强度没有明显变化.%Melted AZ31 magnesium alloy ingot and commercial magnesium alloy AZ31 material were deformed different procedures and cycles by continuous variable section extrusion cycle. The results showed that CVCE technology can make the material structure refine, and the refining effect was very notable. As the deformation amount increases, average grain size decreases, structure tends to homogeneous. When the real strain is 16, its average grain size is 5.5 μm and homogeneous. As the cycle index increases, elongation percentage increases end to end, comparing to that of before deformation, it increases about 2 times.

  12. Achieving Superplasticity in AZ31 Magnesium Alloy Processed by Hot Extrusion and Rolling

    Science.gov (United States)

    Wang, Xin; Wu, Mengling; Ma, Wenliang; Lu, Yi; Yuan, Shuai

    2016-01-01

    Experiments were conducted on ultrafine-grained AZ31 magnesium alloy sheet which was prepared through nano-grained powders processed by hot extrusion at 300 °C plus hot-rolling for four passes at 200. The superplastic behavior had been evaluated in a low-temperature range of 423-523 K and strain rates varied from 5 × 10-4 to 5 × 10-3 s-1. The experiment results showed that tensile testing revealed the superplastic elongations with a maximum measured elongation of 227% when tested at 523 K and strain rate of 5 × 10-4 s-1. The superplastic deformation behavior was attributed to the ultrafine-grained microstructures. The measured elongations mainly depended upon the initial strain rate and temperature, and the strain rate sensitivity m was ~0.5 for this condition. The results indicated that powder metallurgy and subsequent hot extrusion plus rolling were promising approaches to produce the ultrafine-grained magnesium alloy sheet with superplasticity.

  13. Dynamic tensile behavior of AZ31B magnesium alloy at ultra-high strain rates

    Directory of Open Access Journals (Sweden)

    Geng Changjian

    2015-04-01

    Full Text Available The samples having {0001} parallel to extruding direction (ED present a typical true stress–true strain curve with concave-down shape under tension at low strain rate. Ultra-rapid tensile tests were conducted at room temperature on a textured AZ31B magnesium alloy. The dynamic tensile behavior was investigated. The results show that at ultra-high strain rates of 1.93 × 102 s−1 and 1.70 × 103 s−1, the alloy behaves with a linear stress–strain response in most strain range and exhibits a brittle fracture. In this case, {10-12}  extension twinning is basic deformation mode. The brittleness is due to the macroscopic viscosity at ultra-high strain rate, for which the external critical shear stress rapidly gets high to result in a cleavage fracture before large amounts of dislocations are activated. Because {10-12} tension twinning, {10-11} compressive twinning, basal slip, prismatic slip and pyramidal slip have different critical shear stresses (CRSS, their contributions to the degree of deformation are very differential. In addition, Schmid factor plays an important role in the activity of various deformation modes and it is the key factor for the samples with different strain rates exhibit various mechanical behavior under dynamic tensile loading.

  14. Influence of shot peening on corrosion properties of biocompatible magnesium alloy AZ31 coated by dicalcium phosphate dihydrate (DCPD).

    Science.gov (United States)

    Mhaede, Mansour; Pastorek, Filip; Hadzima, Branislav

    2014-06-01

    Magnesium alloys are promising materials for biomedical applications because of many outstanding properties like biodegradation, bioactivity and their specific density and Young's modulus are closer to bone than the commonly used metallic implant materials. Unfortunately their fatigue properties and low corrosion resistance negatively influenced their application possibilities in the field of biomedicine. These problems could be diminished through appropriate surface treatments. This study evaluates the influence of a surface pre-treatment by shot peening and shot peening+coating on the corrosion properties of magnesium alloy AZ31. The dicalcium phosphate dihydrate coating (DCPD) was electrochemically deposited in a solution containing 0.1M Ca(NO3)2, 0.06M NH4H2PO4 and 10mL/L of H2O2. The effect of shot peening on the surface properties of magnesium alloy was evaluated by microhardness and surface roughness measurements. The influence of the shot peening and dicalcium phosphate dihydrate layer on the electrochemical characteristics of AZ31 magnesium alloy was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy in 0.9% NaCl solution at a temperature of 22±1°C. The obtained results were analyzed by the Tafel-extrapolation method and equivalent circuit method. The results showed that the application of shot peening process followed by DCPD coating improves the properties of the AZ31 surface from corrosion and mechanical point of view. PMID:24863232

  15. Dry sliding tribological behavior of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

    International Nuclear Information System (INIS)

    The dry sliding tribological behavior of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at energy density of 3.4 J/cm2 with 10 shots is investigated by dry sliding wear tests in order to explore the effect of HIPIB irradiation on tribological property of magnesium alloy. Surface morphologies, composition and structure of the irradiated AZ31 magnesium alloys are examined by electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The results indicated that HIPIB irradiation led to the increase in surface microhardness and the reduction in friction coefficient and wear rate. Wear rate for both the original and the irradiated samples increased with increasing sliding load from 0.1 to 0.5 N. The transition from severe metallic wear to mild oxidative wear induced by HIPIB irradiation was observed by a combined analysis in surface morphology and chemical composition of wear tracks, mechanically mixed materials and wear debris, which is mainly attributed to the significant increase in microhardness resulting from grain refinement on the irradiated surface. In addition, defects induced by HIPIB irradiation promoted the diffusion of oxygen during sliding wear and therefore led to the formation of compact mixed materials and protective films on the wear tracks surface, which also contributes to the transition in wear mechanism of AZ31 magnesium alloy induced by HIPIB irradiation.

  16. Preliminary research on a novel bioactive silicon doped calcium phosphate coating on AZ31 magnesium alloy via electrodeposition.

    Science.gov (United States)

    Qiu, Xun; Wan, Peng; Tan, Lili; Fan, Xinmin; Yang, Ke

    2014-03-01

    A silicon doped calcium phosphate coating was obtained successfully on AZ31 alloy substrate via pulse electrodeposition. A novel dual-layer structure was observed with a porous lamellar-like and outer block-like apatite layer. In vitro immersion tests were adopted in simulated body fluid within 28 days of immersion. Slow degradation rate obtained from weight loss was observed for the Si-doped Ca-P coating, which was also consistent with the results of electrochemical experiments showing an enhanced corrosion resistance for the coating. Further formation of an apatite-like layer on the surface after immersion proved better integrity and biomineralization performance of the coating. Biological characterization was carried out for viability, proliferation and differentiation of MG63 osteoblast-like cells. The coating showed a good cell growth and an enhanced cell proliferation. Moreover, an increased activity of osteogenic marker ALP was found. All the results demonstrated that the Si-doped calcium phosphate was perspective to be used as a coating for magnesium alloy implants to control the degradation rate and enhance the bioactivity, which would facilitate the rapidity of bone tissue repair. PMID:24433888

  17. AZ31镁合金400°C本构律之有限元验证分析%Finite element verification on constitutive law of AZ31 magnesium alloy at 400 °C

    Institute of Scientific and Technical Information of China (English)

    曾世聪; 胡宣德

    2013-01-01

    A constitutive law is offered for an AZ31B-H24 Mg alloy within a strain rate range of 10-5-10-2 s-1 at a temperature of 400 °C. The constitutive law, which is developed by curve fitting the tensile tests data, is expressed as a flow stress function of strain and strain rate. Furthermore, the constitutive law is embedded into a proper FE model to simulate the tensile experiments for the purpose of verifying reliability, where the incremental stress-strain relationships are calculated by an elastic-plastic theory in the finite element analysis (FEA). The results show that the stress-strain characteristics and the final deformed shapes in the FEA agree well with the experiments. In addition, the predicting analysis of constant-velocity stretch conditions and the verification of a free bulge forming experiment show that the proposed FE model is practicable for mechanical analysis on superplastic forming problems. A selective numerical method is offered for advanced superplastic analysis on AZ31 Mg alloys.%本文以曲线拟合方法,分析AZ31B-H24镁合金的单轴拉伸试验,针对材料在400°C温度下,应变率ε&=10-5-10-2 s-1范围之应力-应变关系曲线,找出一个以应变、应变率为函数的应力流方程式之本构模型,并将此模型掺入有限元(FEM)建构一合理的数值分析模式,仿真该单轴拉伸试验,以验证其可靠性。有限元分析(FEA)时以固体力学的弹-塑性理论来运算材料塑性流演化行为的应力增量-应变增量之关系。分析结果显示,FEA与单轴拉伸试验的应力-应变关系曲线,在各变形阶段上,二者皆具有相当不错的吻合性;且实验与FEA在极限应变状态下之杆件的变形形状,二者结果亦相当接近;本文并以此FEM分析模式预测固定速率之单轴拉伸案例,对该材料的吹制成型试验进行仿真,结果亦验证了本文所提出的本构模型拥有超塑性成型力学分析的实用性。本文对AZ

  18. The Origin of Fracture in the I-ECAP of AZ31B Magnesium Alloy

    Science.gov (United States)

    Gzyl, Michal; Rosochowski, Andrzej; Boczkal, Sonia; Qarni, Muhammad Jawad

    2015-11-01

    Magnesium alloys are very promising materials for weight-saving structural applications due to their low density, comparing to other metals and alloys currently used. However, they usually suffer from a limited formability at room temperature and low strength. In order to overcome those issues, processes of severe plastic deformation (SPD) can be utilized to improve mechanical properties, but processing parameters need to be selected with care to avoid fracture, very often observed for those alloys during forming. In the current work, the AZ31B magnesium alloy was subjected to SPD by incremental equal-channel angular pressing (I-ECAP) at temperatures varying from 398 K to 525 K (125 °C to 250 °C) to determine the window of allowable processing parameters. The effects of initial grain size and billet rotation scheme on the occurrence of fracture during I-ECAP were investigated. The initial grain size ranged from 1.5 to 40 µm and the I-ECAP routes tested were A, BC, and C. Microstructures of the processed billets were characterized before and after I-ECAP. It was found that a fine-grained and homogenous microstructure was required to avoid fracture at low temperatures. Strain localization arising from a stress relaxation within recrystallized regions, namely twins and fine-grained zones, was shown to be responsible for the generation of microcracks. Based on the I-ECAP experiments and available literature data for ECAP, a power law between the initial grain size and processing conditions, described by a Zener-Hollomon parameter, has been proposed. Finally, processing by various routes at 473 K (200 °C) revealed that route A was less prone to fracture than routes BC and C.

  19. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature

    Science.gov (United States)

    Park, Jingee; Lee, Jongshin; You, Bongsun; Choi, Seogou; Kim, Youngsuk

    2007-05-01

    Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation of steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model.

  20. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature

    International Nuclear Information System (INIS)

    Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation of steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model

  1. Lap shear strength and fatigue life of friction stir spot welded AZ31 magnesium and 5754 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, S.H. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3 (Canada); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3 (Canada); Bhole, S.D. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada M5B 2K3 (Canada); Cao, X.; Wanjara, P. [Aerospace Manufacturing Technology Centre, National Research Council Canada, 5145 Decelles Avenue, Montreal, Quebec, Canada H3T 2B2 (Canada)

    2012-10-30

    Lightweighting is today considered as one of the key strategies in reducing fuel consumption and anthropogenic greenhouse gas emissions. The structural applications of lightweight magnesium and aluminum alloys in the transportation industry inevitably involve welding and joining while guaranteeing the safety and reliability of motor vehicles. This study was aimed at evaluating lap shear strength and fatigue properties of friction stir spot welded (FSSWed) AZ31B-H24 Mg and 5754-O Al alloys in three combinations, i.e., similar Mg-to-Mg, Al-to-Al, and dissimilar Al-to-Mg joints. The Mg/Mg similar weld had a nugget-shaped stir zone (SZ) around the keyhole where fine recrytallized equiaxed grains were observed. While the hardness profile of the Mg/Mg similar weld exhibited a W-shaped appearance, the lower hardness values appeared in the TMAZ and HAZ of both Mg/Mg and Al/Al similar welds. In the Al/Mg dissimilar weld, a characteristic interfacial layer consisting of intermetallic compounds (IMC) Al{sub 12}Mg{sub 17} and Al{sub 3}Mg{sub 2} was observed. Both Mg/Mg and Al/Al similar welds had significantly higher lap shear strength, failure energy and fatigue life than the Al/Mg dissimilar weld. While the Al/Al weld displayed a slightly lower lap shear strength than the Mg/Mg weld, the Al/Al weld had higher failure energy and fatigue life. Three types of failure modes were observed. In the Mg/Mg and Al/Al similar welds, at higher cyclic loads nugget pullout failure occurred due to fatigue crack propagation circumferentially around the nugget, while at lower cyclic loads fatigue failure occurred perpendicular to the loading direction caused by the opening of keyhole through crack initiation in the TMAZ and HAZ. In the Al/Mg dissimilar weld nugget debonding failure mode was observed because of the presence of an interfacial IMC layer.

  2. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    OpenAIRE

    D. Thirumalaikumarasamy; K. Shanmugam; Balasubramanian, V

    2014-01-01

    Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 w...

  3. Experimental study on tensile property of AZ31B magnesium alloy at different high strain rates and temperatures

    International Nuclear Information System (INIS)

    Highlights: • Fracture elongation of AZ31B under high strain rate is larger than quasi-static. • Fracture elongation reduce with the increasing of strain rate under high strain rate. • The improvement plasticity may be attributed to adiabatic heating. • Fracture pattern of AZ31B quasi-static tensile at room temperature is quasi-cleavage. • Fracture pattern of AZ31B under high strain rate high temperature is ductile fracture. - Abstract: As the lightest metal material, magnesium alloy is widely used in the automobile and aviation industries. Due to the crashing of the automobile is a process of complicated and highly nonlinear deformation. The material deformation behavior has changed significantly compared with quasi-static, so the deformation characteristic of magnesium alloy material under the high strain rate has great significance in the automobile industry. In this paper, the tensile deformation behavior of AZ31B magnesium alloy is studied over a large range of the strain rates, from 700 s−1 to 3 × 103 s−1 and at different temperatures from 20 to 250 °C through a Split-Hopkinson Tensile Bar (SHTB) with heating equipment. Compared with the quasi-static tension, the tensile strength and fracture elongation under high strain rates is larger at room temperature, but when at the high strain rates, fracture elongation reduces with the increasing of the strain rate at room temperature, the adiabatic temperature rising can enhance the material plasticity. The morphology of fracture surfaces over wide range of strain rates and temperatures are observed by Scanning Electron Microscopy (SEM). The fracture appearance analysis indicates that the fracture pattern of AZ31B in the quasi-static tensile tests at room temperature is mainly quasi-cleavage pattern. However, the fracture morphology of AZ31B under high strain rates and high temperatures is mainly composed of the dimple pattern, which indicates ductile fracture pattern. The fracture mode is a

  4. Influence of local strain on twinning behavior during compression of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.T., E-mail: huanghongtao401@163.com [Laboratory for Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Department of Reactor Engineering Research and Design, China Institute of Atomic Energy, Beijing 102413 (China); Godfrey, A. [Laboratory for Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zheng, J.P. [Department of Reactor Engineering Research and Design, China Institute of Atomic Energy, Beijing 102413 (China); Liu, W. [Laboratory for Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-07-29

    The effect of local strain state on twinning behavior during compression of AZ31 magnesium alloy was investigated, making use of a micro-grid method to correlate the local strain tensor with observations of twinning using electron backscatter diffraction (EBSD) measurements. Eight prism samples were used to get deformation zones subjected to different strain states. The strain distribution across the whole sample surface was measured with the micro-grid method and the results show that the local strain states exhibit much variation, with zones subjected to large shear strain as well as zones subjected to little shear strain. Samples were compressed at room temperature and detailed EBSD measurements were taken in two zones, where one zone was subject to only small shear strains and the other was subject to large shear strains. Twin variant selection was then analyzed with respect to both stress-based (Schmid factor) and strain-based criteria. The former was found to provide the best explanation for the observed pattern of twinning.

  5. Influence of local strain on twinning behavior during compression of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    The effect of local strain state on twinning behavior during compression of AZ31 magnesium alloy was investigated, making use of a micro-grid method to correlate the local strain tensor with observations of twinning using electron backscatter diffraction (EBSD) measurements. Eight prism samples were used to get deformation zones subjected to different strain states. The strain distribution across the whole sample surface was measured with the micro-grid method and the results show that the local strain states exhibit much variation, with zones subjected to large shear strain as well as zones subjected to little shear strain. Samples were compressed at room temperature and detailed EBSD measurements were taken in two zones, where one zone was subject to only small shear strains and the other was subject to large shear strains. Twin variant selection was then analyzed with respect to both stress-based (Schmid factor) and strain-based criteria. The former was found to provide the best explanation for the observed pattern of twinning

  6. Wettability and corrosion of alumina embedded nanocomposite MAO coating on nanocrystalline AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gheytani, M.; Aliofkhazraei, M., E-mail: maliofkh@gmail.com; Bagheri, H.R.; Masiha, H.R.; Rouhaghdam, A. Sabour

    2015-11-15

    In this paper, micro- and nanocrystalline AZ31B magnesium alloy were coated by micro-arc oxidation method. In order to fabricate nanocrystalline surface layer, surface mechanical attrition treatment was performed and nano-grains with average size of 5–10 nm were formed on the surface of the samples. Coating process was carried out at different conditions including two coating times and two types of electrolyte. Alumina nanoparticles were utilized as suspension in electrolyte to form nanocomposite coatings by micro-arc oxidation method. Potentiodynamic polarization, percentage of porosity, and wettability tests were performed to study various characteristics of the coated samples. The results of scanning electron microscope imply that samples coated in silicate-based electrolyte involve much lower surface porosity (∼25%). Besides, the results of wettability test indicated that the maximum surface tension with deionized water is for nanocrystalline sample. In this regard, the sample coated in silicate-based suspension was 4 times more hydrophilic than the microcrystalline sample. - Highlights: • MAO in phosphate electrolyte needs higher energy as compared to silicate electrolyte. • Less porosity and finer grain size on free surface of the silicate-based coatings. • Observed porosity from top surface of coating shows the effect of the final MAO sparks. • SMAT affects surface roughness and accelerates growth kinetics.

  7. Material flow and microstructural evolution during friction stir spot welding of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, W. [Center for Friction Stir Processing, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Mishra, R.S., E-mail: rajiv.mishra@unt.edu [Center for Friction Stir Processing, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Department of Materials Science and Engineering, University of North Texas, Denton, TX 76203 (United States); Carlson, B.; Verma, R.; Mishra, R.K. [General Motors R and D Center, Warren, MI 48090 (United States)

    2012-05-01

    Material flow and local texture evolution during friction stir spot welding (FSSW) of AZ31 magnesium alloy was characterized by varying tool rotation rates. Texture at various locations of the welded region was measured using electron backscatter diffraction (EBSD). Material flow is significantly influenced by tool rotation rate with a conical step spiral pin tool, and FSSW introduces a unique basal fiber texture in the welded region. Results indicate that local texture evolution is dominated by shear deformation through material flow. The tool shoulder applies both shear and compressive deformation to the upper region material; however, the rotating pin introduces only shear deformation to the adjacent material. As the tool rotation rate increases, the effect of both tool shoulder and pin becomes more prominent by introducing a higher degree of basal pole tilt with respect to the initial rolling texture at the periphery of the pin, but less tilt in the upper region beneath the tool shoulder undersurface. The equiaxed fine grain structure in the stir zone appears to result from the twinning-induced dynamic recrystallization and discontinuous dynamic recrystallization.

  8. The correlation between the impression and double shear creep of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    This study reports the application of an impression creep test to measure the creep behavior of AZ31 magnesium alloy. The correlation between the impression and double shear creep data on the same sample was determined. The creep parameters determined via impression and double shear creep assessments were found to be identical, with n = ∼3.5 and Q = ∼109.1 kJ/mol in the low-stress region, indicating that creep deformation was found to be controlled by the viscous glide of dislocations and that the viscous glide was governed by the diffusion of aluminum atoms in magnesium. The punching stress conversion factor α was determined to be 3.4 with a correlation factor β = 0.755. The Dorn constant A was determined to be 11.4 s−1. The ratio of As to Ai was 967.8, which is close to the predicted value of 928.6. This fact indicates that the impression creep relationship and double shear creep relationship can be converted into the equivalent uniaxial creep relationship.

  9. Characteristics of magnesium AZ31 alloys subjected to high speed rolling

    International Nuclear Information System (INIS)

    Magnesium AZ31 alloy sheets were rolled at a high (1000 m/min) and a low (15 m/min) rolling speed. The microstructure and texture evolution were tracked using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) techniques. At 100 °C, a total reduction of 72% was achieved in one pass at the high rolling speed, while the sheet fractured at a reduction of only 37% during low speed rolling. In the former case, dynamic recrystallization was observed to be well under way at a reduction of 49% and full recrystallization was achieved at a reduction of 72%. For a given reduction, the maximum intensity of the basal texture is weaker after high speed rolling than after low speed rolling. The far better rollability achieved during high speed rolling is attributed to the activation of slip and dynamic recrystallization at the higher temperatures developed; the weaker texture is due to the activation of a larger number of twinning and slip systems

  10. Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

    Directory of Open Access Journals (Sweden)

    Karl Ulrich Kainer

    2012-08-01

    Full Text Available The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 °C, 350 °C and 450 °C have been studied in compression. The extruded material had a fiber texture with  parallel to the extrusion axis. When extruded at 450 °C, the texture was less intense and the  direction moved away from the extrusion axis. The processing maps for the material extruded at 300 °C and 350 °C are qualitatively similar to the material with near-random texture (cast-homogenized and exhibited three dynamic recrystallization (DRX domains. In domains #1 and #2, prismatic slip is the dominant process and DRX is controlled by lattice self-diffusion and grain boundary self-diffusion, respectively. In domain #3, pyramidal slip occurs extensively and DRX is controlled by cross-slip on pyramidal slip systems. The material extruded at 450 °C exhibited two domains similar to #1 and #2 above, which moved to higher temperatures, but domain #3 is absent. The results are interpreted in terms of the changes in  fiber texture with extrusion temperature. Highly intense  texture, as in the rod extruded at 350 °C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 °C (domain #3.

  11. Wettability and corrosion of alumina embedded nanocomposite MAO coating on nanocrystalline AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    In this paper, micro- and nanocrystalline AZ31B magnesium alloy were coated by micro-arc oxidation method. In order to fabricate nanocrystalline surface layer, surface mechanical attrition treatment was performed and nano-grains with average size of 5–10 nm were formed on the surface of the samples. Coating process was carried out at different conditions including two coating times and two types of electrolyte. Alumina nanoparticles were utilized as suspension in electrolyte to form nanocomposite coatings by micro-arc oxidation method. Potentiodynamic polarization, percentage of porosity, and wettability tests were performed to study various characteristics of the coated samples. The results of scanning electron microscope imply that samples coated in silicate-based electrolyte involve much lower surface porosity (∼25%). Besides, the results of wettability test indicated that the maximum surface tension with deionized water is for nanocrystalline sample. In this regard, the sample coated in silicate-based suspension was 4 times more hydrophilic than the microcrystalline sample. - Highlights: • MAO in phosphate electrolyte needs higher energy as compared to silicate electrolyte. • Less porosity and finer grain size on free surface of the silicate-based coatings. • Observed porosity from top surface of coating shows the effect of the final MAO sparks. • SMAT affects surface roughness and accelerates growth kinetics

  12. Potentiostatic Conversion of Phosphate Mineral Coating on AZ31 Magnesium Alloy in 0.1 M K2HPO4 Solution

    International Nuclear Information System (INIS)

    Highlights: • A four layered phosphate coating was electro-deposited on AZ31 alloy in deaerated 0.1 M K2HPO4 solution with pH 9.5. • The formation process of phosphate conversion coating contains five characterization stages. • Amorphous Mg(OH)2, MgHPO4 and crystallized KMgPO4• 6H2O are in sequence deposited to form the conversion coating. • The innermost layer of the coating consists of Mg(OH)2, and the inner layer consists of Mg(OH)2 and MgHPO4. • The middle layer consists of Mg(OH)2, MgHPO4 and KMgPO4• 6H2O, and the topmost layer consists of MgHPO4 and KMgPO4• 6H2O. - Abstract: The coating process of a four layered phosphate mineral conversion coating on AZ31 Mg alloy deposited at −0.8 V in 0.1 M K2HPO4 solution with pH 9.5 was studied by in situ potentiostatic polarization, together with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetry (TG), differential scanning calorimetry (DSC), differential thermal gravimetry (DTG) and electron probe micro-analyzer (EPMA). Our results show that the coating process can be divided into five stages. The initial two stages are caused by the rapid decrease of charging current of the electrical double layer capacitance and the slow increase of faraday current density on AZ31 Mg alloy, and Mg(OH)2 was detected in the corrosion product in these two stages. The third process corresponds to the deposition of amorphous MgHPO4 film, followed by the fourth process corresponding to the decrease of the corrosion resistance of MgHPO4. In the last stage, crystallized KMgPO4 · 6H2O (struvite-K) forms. The SEM, XPS, TG, DSC, DTG and EPMA indicate that the deposited coating consists of four layers. The innermost layer is composed of a corosion product, Mg(OH)2, followed by the inner layer composed of Mg(OH)2 and MgHPO4, subsequently the middle layer consisting of Mg(OH)2, MgHPO4 and struvite-K, and finally the

  13. Research on Relationship of AZ31B Magnesium Alloy Fracture Strain and Stress Triaxiality%AZ31B镁合金断裂应变与应力三轴度的关系研究

    Institute of Scientific and Technical Information of China (English)

    周梦成; 冯飞; 胡建华; 雷雨; 何鹏; 黄尚宇; 邹方利

    2015-01-01

    AZ31 B镁合金光滑圆棒和缺口圆棒进行了系列准静态拉伸试验,采用 ABAQUS 对各试样拉伸过程进行了模拟分析。拟合得到了 Johnson-Cook 断裂失效模型的部分材料常数,建立了AZ31 B镁合金断裂应变与应力三轴度的关系模型。将建立的失效模型输入到ABAQUS中进行仿真模拟,模拟结果与试验结果基本一致,验证了断裂失效模型的正确性。%Series of quasi-static tensile tests were conducted on smooth and notched round rod made of AZ31B magnesium alloy.ABAQUS software was used to simulate the tensile process of each sample.Part material constants of Johnson-Cook fracture failure model were fitted out,and the rela-tional model between fracture strain and stress triaxiality of AZ31B magnesium alloy were estab-lished.Inputing the fracture failure model into ABAQUS for simulation,the simulation results and ex-perimental results are basically consistent,thus the correctness of the fracture failure model was veri-fied.

  14. Influence of second-phase particles on grain growth in AZ31 magnesium alloy during equal channel angular pressing by phase field simulation

    Science.gov (United States)

    He, Ri; Wang, Mingtao; Zhang, Xiangang; Yaping Zong, Bernie

    2016-06-01

    A phase-field model was established to simulate the refinement effect of different morphological factors of second-phase particles such as Al2O3 on the grain growth of AZ31 magnesium alloy during equal channel angular pressing (ECAP) in realistic spatiotemporal evolution. The simulation results agreed well with limited existing experimental data for the ECAP-processed AZ31 magnesium alloy and were consistent with the law of Zener. Simulations were performed to evaluate the influences of the fraction, size, distribution, and shape of incoherent second-phase particles. The simulation results showed that during high-temperature ECAP processes, the addition of 2 wt.% Al2O3 particles resulted in a strong refinement effect, reducing the grain size by 28.7% compared to that of the alloy without the particles. Nevertheless, when the fraction of particles was greater than 4 wt.%, adding more particles had little effect. In AZ31 Mg alloy, it was found that second-phase particles should have a critical size of 0.5–0.8 μm for the grain refinement effect to occur. If the size is smaller than the critical size, large particles will strongly hinder grain growth; in contrast, if the size is larger than the critical size, large particles will exhibit a weaker hindering effect than small particles. Moreover, the results showed that the refinement effect increased with increasing particle fraction located at grain boundaries with respect to the total particle content. However, the refinement effect was less pronounced when the fraction of particles located at boundaries was greater than 70%. Further simulations indicated that spherical second-phase particles hindered grain growth more than ellipsoid particles and much more than rod-shaped particles when the volume fraction of reinforcing particles was 2%. However, when the volume fraction was greater than 8%, rod-shaped particles best hindered grain growth, and spherical particles exhibited the weakest effect.

  15. Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant

    International Nuclear Information System (INIS)

    This study was conducted to identify the differences between corrosion rates, corrosion types, and corrosion products in different physiological environments for AZ31 magnesium alloy and plasma electrolytic oxidation (PEO) treated AZ31 magnesium alloy. In vitro and in vivo tests were performed in Hank's Balanced Salt Solution (HBSS) and mice for 12 weeks, respectively. The corrosion rates of both AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy were calculated based on DC polarization curves, volume of hydrogen evolution, and the thickness of corrosion products formed on the surface. Micro X-ray computed tomography (Micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to analyze morphological and chemical characterizations of corrosion products. The results show that there is more severe localized corrosion after in vitro test in HBSS; however, the thicknesses of corrosion products formed on the surface for AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy in vivo were about 40% thicker than the thickness of corrosion products generated in vitro. The ratio of Ca and P (Ca/P) in the corrosion products also differed. The Ca deficient region and higher content of Al in corrosion product than AZ31 magnesium alloy were identified after in vivo test in contrast with the result of in vitro test. - Highlights: • Effects of plasma electrolytic oxidation on AZ31 in vitro and in vivo • Retardation of degradation via plasma electrolytic oxidation in vitro and in vivo • Differentiation of in vitro and in vivo corrosion types and products

  16. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    Science.gov (United States)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-03-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  17. Mussel-inspired functionalization of PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Tian, Peng; Xu, Demin; Liu, Xuanyong

    2016-05-01

    The rapid degradation of magnesium-based implants in physiological environments in vivo not only will quickly deteriorate their mechanical strengths but will also lead to a severe change of the micro-environment around the implants, which may cause the final failure of magnesium-based implants. In this work, a polycaprolactone (PCL) layer was prepared to seal the plasma electrolytic oxidization coating (PEO) to form a PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy, followed by further surface functionalization with polydopamine. The in vitro degradation behaviors of the bare AZ31 alloy and coated samples were evaluated in a simulated body fluid (SBF) using the potentiodynamic polarization curve test and the static immersion test. The bioactivity of the samples was investigated using the SBF soaking test. The cytocompatibility of all samples was evaluated using the cytotoxicity test and analysis of the adhesion and proliferation of osteoblast cells (MC3T3-E1) directly cultivated on the sample surface. The results showed that the PCL layer successfully sealed the pores of the PEO coating, and then the polydopamine layer formed on its surface. The in vitro degradation tests showed that the PEO/PCL composite coating improved the corrosion resistance of the AZ31 alloy in SBF with a more positive corrosion potential and a lower corrosion current density. Due to the protection of the PEO/PCL composite coating, the surrounding environment showed nearly no influence on the degradation of the coated sample, which led to no obvious local alkalization and hydrogen evolution. Moreover, compared with the AZ31 alloy and PEO coating, the PEO/PCL composite coating was more suitable for cell adhesion and proliferation. After further surface functionalization by polydopamine, the corrosion resistance of the composite coating was maintained, while its bioactivity was significantly enhanced with a large amount of hydroxyapatite (HA) formed on its surface after

  18. Effect of the chemistry and structure of the native oxide surface film on the corrosion properties of commercial AZ31 and AZ61 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, Sebastian, E-mail: sfeliu@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Maffiotte, C. [CIEMAT-DT edificio 30, Avda. Complutense, 22, 28040 Madrid (Spain); Samaniego, A.; Galvan, Juan Carlos [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Barranco, Violeta [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Instituto de Ciencias de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Cientificas, CSIC, Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049, Madrid (Spain)

    2011-08-01

    The purpose of this study has been to advance in knowledge of the chemical composition, structure and thickness of the thin native oxide film formed spontaneously in contact with the laboratory atmosphere on the surface of freshly polished commercial AZ31 and AZ61 alloys with a view to furthering the understanding of protection mechanisms. For comparative purposes, and to more fully describe the behaviour of the native oxide film, the external oxide films formed as a result of the manufacturing process (as-received condition) have been characterised. The technique applied in this research to study the thin oxide films (thickness of just a few nanometres) present on the surface of the alloys has basically been XPS (X-ray photoelectron spectroscopy) in combination with ion sputtering. Corrosion properties of the alloys were studied in 0.6 M NaCl by measuring charge transfer resistance values, which are deduced from EIS (electrochemical impedance spectroscopy) measurements after 1 h of exposure. Alloy AZ61 generally showed better corrosion resistance than AZ31, and the freshly polished alloys showed better corrosion resistance than the alloys in as-received condition. This is attributed to a combination of (1) higher thickness of the native oxide film on the AZ61 alloy and (2) greater uniformity of the oxide film in the polished condition. The formation of an additional oxide layer composed by a mixture of spinel (MgAl{sub 2}O{sub 4}) and MgO seems to diminish the protective properties of the passive layer on the surface of the alloys in as-received condition.

  19. Dynamic behaviors of a Ca–P coated AZ31B magnesium alloy during in vitro and in vivo degradations

    International Nuclear Information System (INIS)

    Surface modification can be an effective way to control the biodegradation behavior of magnesium alloys and even improve their biological properties. Much attention has been paid to the initial protection ability and biological properties of magnesium alloys coating. In this work, the dynamic behaviors of a Ca–P coated AZ31B magnesium alloy during the degradations in vitro and in vivo, including hemolysis, mechanical loading capability and implantation in animals, were investigated. The hemolytic rates of the alloy with and without coating were all declined to be lower than 5% after more than 20 days immersion in PBS, though an increase happened to the alloy at the early immersion of 3–7 days. Reduction of the mechanical loading capacity was gradually evolved for the coated alloy and the peak load retention of 85% was still maintained after 120 days degradation. The in vivo implantation indicated that the Ca–P coated AZ31B alloy showed a more suitable time dependent degradation behavior which was favorable for growth of the new tissue and the healing dynamics of bones, making it a promising choice for medical application.

  20. Mechanical Behavior and Microstructural Analysis of Extruded AZ31B Magnesium Alloy Processed by Backward Extrusion

    Science.gov (United States)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.; Grünheid, Thomas

    2016-07-01

    This study investigates the mechanical behavior of an extruded AZ31B magnesium alloy profile at various strain rates from 0.001 to 375/s. The electron backscatter diffraction analysis revealed that the profile has \\{ { 0 0 0 1} \\}extrusion direction (ED), the profile shows the highest yield strength (YS) but the lowest total elongation at fracture (TE) due to a hard activation of non-basal slip and \\{ { 1 0overline{1} 1} \\}< { 1 0overline{1} overline{2} } rangle twinning; in the diagonal direction (DD), it shows the lowest ultimate tensile strength (UTS) but the highest TE due to an easy activation of basal slip; in the transverse direction (TD), it shows the lowest YS due to an easy activation of \\{ {10overline{1} 2} \\}< {10overline{1} overline{1} } rangle twinning. Moreover, the number of twins increases with the increasing strain rate. This indicates that deformation twinning becomes prevalent to accommodate high-rate deformation. Due to the different deformation mechanisms, the profile exhibits an orientation-dependent effect of strain rate on the mechanical properties. A positive effect of strain rate on the YS and UTS was found in the ED, while the effect of strain rate on the YS is negligible in the DD and TD. The TE in the ED, DD, and TD decreases in general as the strain rate increases. Fractographic analysis under a scanning electron microscope revealed that the fracture is a mixed mode of ductile and brittle fracture, and the magnesium oxide inclusions could be the origins of the fracture.

  1. Influence of chloride ion concentration on immersion corrosion behaviour of plasma sprayed alumina coatings on AZ31B magnesium alloy

    OpenAIRE

    D. Thirumalaikumarasamy; K. Shanmugam; Balasubramanian, V

    2014-01-01

    Corrosion attack of aluminium and magnesium based alloys is a major issue worldwide. The corrosion degradation of an uncoated and atmospheric plasma sprayed alumina (APS) coatings on AZ31B magnesium alloy was investigated using immersion corrosion test in NaCl solutions of different chloride ion concentrations viz., 0.01 M, 0.2 M, 0.6 M and 1 M. The corroded surface was characterized by an optical microscope and X-ray diffraction. The results showed that the corrosion deterioration of uncoate...

  2. Evaluation of the Quality of Coatings Deposited on AZ31 Magnesium Alloy Using the Anodising Method / Ocena Jakości Powłok Wykonanych Na Stopie Magnezu Az31 Metodą Anodowania

    OpenAIRE

    Wieczorek J.; Oleksiak B.; Mizera J.; Kulikowski K.; Maj P.

    2015-01-01

    The paper presents results of a study on the quality of coatings deposited on surfaces of AZ31 magnesium alloy products. In order to obtain protective coatings (corrosion and erosive wear protection), the methods of anodising (specimens A, B and C) and, for comparison, electroless plating (specimen D) were applied. The assessment of coating quality was based on the scratch test results. The results were used for determination of critical loads resulting in coating rupture. The best result was...

  3. Development of surface composite based on Mg–Al–Ni system on AZ31 magnesium alloy and evaluation of formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Abdollahi, S.H.; Karimzadeh, F., E-mail: karimzadeh_f@cc.iut.ac.ir; Enayati, M.H.

    2015-02-25

    Highlights: • This research showed that by applying friction stir processing (FSP) in-situ surface composite based on Mg–Al/Ni alloying systems is produced on AZ31 plate under different FSP passes. • Thermodynamic and kinetic study of interfacial solid state reactions confirmed phase formation during different FSP passes. • Moreover, the effective Gibbs free energy of formation graphs for the compounds were plotted at 711 K. • Based on kinetic standpoint, schematic diagram of Mg–Ni intermetallic compounds during difference FSP passes is plotted. • Due to presence of intermetallic phases the mean hardness of the stir zone reached about 106 Hv, which is about two times higher than the base metal. - Abstract: The in-situ synthesis of Mg–Al–Ni composite on the surface of AZ31 plate by friction stir processing (FSP), has been investigated in this article. The unprocessed AZ31 plate consisted of grains of 25 μm size. By increasing the number of FSP passes from one to five, the grain size of the AZ31 plate decreased to 7.5 and 3 μm, respectively. A uniform distribution of the reinforcements was also obtained by increasing the number of FSP passes. Based on the results of X-ray diffraction (XRD) and Energy dispersive spectrometry (EDS) analyses, Mg{sub 2}Ni and Al{sub 3}Ni{sub 2} intermetallic compounds are in-situ formed by a single-pass FSP of the composite specimens. By increasing the number of FSP passes, the amounts of Mg{sub 2}Ni and Al{sub 3}Ni{sub 2} compounds are dramatically reduced and AlNi and MgNi{sub 2} intermetallic compounds take their place. Thermodynamic and kinetic of interfacial solid state reactions were studied to determine the reactive mechanisms and phase evolutions during different passes of FSP. The maximum amount of hardness (∼106 Hv), was obtained for the composite sample after five passes of FSP.

  4. In vitro degradation behavior and cytocompatibility of biodegradable AZ31 alloy with PEO/HT composite coating.

    Science.gov (United States)

    Tian, Peng; Liu, Xuanyong; Ding, Chuanxian

    2015-04-01

    Biodegradable magnesium-based implants have attracted much attention recently in orthopedic applications because of their good mechanical properties and biocompatibility. However, their rapid degradation in vivo will not only reduce their mechanical strength, but also induce some side effects, such as local alkalization and gas cavity, which may lead to a failure of the implant. In this work, a hydroxyapatite (HA) layer was prepared on plasma electrolytic oxidization (PEO) coating by hydrothermal treatment (HT) to fabricate a PEO/HT composite coating on biodegradable AZ31 alloy. The in vitro degradation behaviors of all samples were evaluated in simulated body fluid (SBF) and their surface cytocompatibility was also investigated by evaluating the adhesion and proliferation of osteoblast cells (MC3T3-E1). The results showed that the HA layer consisted of a dense inner layer and a needle-like outer layer, which successfully sealed the PEO coating. The in vitro degradation tests showed that the PEO/HT composite coating improved the corrosion resistance of AZ31 alloy in SBF, presenting nearly no severe local alkalization and hydrogen evolution. The lasting corrosion resistance of the PEO/HT composite coating may attribute to the new hydroxyapatite formation during the degradation process. Moreover, compared with AZ31 alloy and PEO coating, PEO/HT composite coating was more suitable for cells adhesion and proliferation, indicating improved surface cytocompatibility. The results show that the PEO/HT composite coating is promising as protective coating on biodegradable magnesium-based implants to enhance their corrosion resistance as well as improve their surface cytocompatibility for orthopedic applications. PMID:25731092

  5. Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading

    Energy Technology Data Exchange (ETDEWEB)

    Asgari, H., E-mail: hamed.asgari@usask.ca [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon (Canada); Odeshi, A.G.; Szpunar, J.A. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon (Canada); Zeng, L.J.; Olsson, E. [Department of Applied Physics, Chalmers University of Technology, Göteborg (Sweden)

    2015-08-15

    The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6, 18 and 37 μm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s{sup −} {sup 1}. It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading. - Highlights: • A double-peak basal texture developed in all shock loaded samples. • Both strength and ductility increased with decreasing grain size. • Twinning fraction and strain hardening rate decreased with decreasing grain size. • ‘g.b’ analysis confirmed the presence of dislocations in shock loaded alloy.

  6. Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading

    International Nuclear Information System (INIS)

    The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6, 18 and 37 μm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s− 1. It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading. - Highlights: • A double-peak basal texture developed in all shock loaded samples. • Both strength and ductility increased with decreasing grain size. • Twinning fraction and strain hardening rate decreased with decreasing grain size. • ‘g.b’ analysis confirmed the presence of dislocations in shock loaded alloy

  7. Microstructure Characteristics and Mechanical Properties of Al-12Si Coatings on AZ31 Magnesium Alloy Produced by Cold Spray Technique

    Science.gov (United States)

    Hao, Yi; Wang, Ji-qiang; Cui, Xin-yu; Wu, Jie; Li, Tie-fan; Xiong, Tian-ying

    2016-06-01

    The cold spray technique was to deposit Al-12Si coatings on AZ31 magnesium alloy. The influence of gas pressure and gas temperature on the microstructure of coatings was investigated so as to optimize the process parameters. OM, SEM, and XRD were used to characterize the as-sprayed coatings. Mechanical properties including Vickers microhardness and adhesion strength were measured in order to evaluate coating quality. Test results indicate that the Al-12Si coatings possess the same crystal structure with powders, sufficient thickness, low porosity, high hardness, and excellent adhesion strength under optimal cold spray process parameters.

  8. Microstructure Characteristics and Mechanical Properties of Al-12Si Coatings on AZ31 Magnesium Alloy Produced by Cold Spray Technique

    Science.gov (United States)

    Hao, Yi; Wang, Ji-qiang; Cui, Xin-yu; Wu, Jie; Li, Tie-fan; Xiong, Tian-ying

    2016-04-01

    The cold spray technique was to deposit Al-12Si coatings on AZ31 magnesium alloy. The influence of gas pressure and gas temperature on the microstructure of coatings was investigated so as to optimize the process parameters. OM, SEM, and XRD were used to characterize the as-sprayed coatings. Mechanical properties including Vickers microhardness and adhesion strength were measured in order to evaluate coating quality. Test results indicate that the Al-12Si coatings possess the same crystal structure with powders, sufficient thickness, low porosity, high hardness, and excellent adhesion strength under optimal cold spray process parameters.

  9. Metallurgical characterization of pulsed current gas tungsten arc, friction stir and laser beam welded AZ31B magnesium alloy joints

    International Nuclear Information System (INIS)

    This paper reports the influences of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on mechanical and metallurgical properties of AZ31B magnesium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy and X-Ray diffraction technique were used to evaluate the metallurgical characteristics of welded joints. LBW joints exhibited superior tensile properties compared to FSW and PCGTAW joints due to the formation of finer grains in weld region, higher fusion zone hardness, the absence of heat affected zone, presence of uniformly distributed finer precipitates in weld region.

  10. Effect of rolling process on microstructures and mechanical properties of AZ31B alloy sheets

    Institute of Scientific and Technical Information of China (English)

    LE Qi-chi; ZHANG Zhi-qiang; CUI Jian-zhong

    2006-01-01

    AZ31B magnesium extruded slabs prepared from LFEC were rolled at fairly lower temperature at 3, 6 and 16 m/min rolling speeds into 1 mm thickness. The results indicate that the microstructures achieved by rolling at low temperature or at low rolling speed are composed of many prismatic regions divided by shear strips due to pile-up of twin crystals; the prismatic regions increase at elevated rolling temperature or at high rolling speed, and finally all are composed of equiaxed crystals without twin crystals due to dynamic recrystallization. After optimizing control of rolling process, excellent mechanical properties would be acquired. The mechanical properties of AZ31B sheet are σb=350 MPa, σ0.2=300 MPa, and δ=12.0% when rolled at 6 m/min. At the same time, the difference of mechanical properties between transverse and longitudinal direction reduced markedly.

  11. An ultrasonic internal friction study of ultrafine-grained AZ31magnesium alloy

    Czech Academy of Sciences Publication Activity Database

    Koller, M.; Sedlák, Petr; Seiner, Hanuš; Ševčík, Martin; Landa, Michal; Stráská, J.; Janeček, M.

    2015-01-01

    Roč. 50, č. 2 (2015), s. 808-818. ISSN 0022-2461 R&D Projects: GA ČR GA13-13616S Institutional support: RVO:61388998 Keywords : AZ31 * internal friction * resonant ultrasound spectroscopy * grain boundary sliding Subject RIV: BI - Acoustics Impact factor: 2.371, year: 2014 http://link.springer.com/article/10.1007/s10853-014-8641-1

  12. Microstructures and mechanical properties of AZ31-0.1Ca magnesium alloy produced by soft-contact electromagnetic casting and hot extrusion

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An AZ31-0.1Ca magnesium alloy produced by Soft-contact electromagnetic continuous casting(SEMC) was investigated.The fine homogeneous structure and the precipitated phases were obtained by SEMC.The effects of microalloying of Ca and middle frequency electromagnetic field on AZ31-0.1Ca magnesium alloy were discussed.And the as-cast billets were extruded with different extrusion ratios subsequently.The alloy showed an ultrafine grain size of 2-5 μm due to dynamic recrytallization(DRX) in the course of hot ext...

  13. Sliding wear behaviour of AZ31B magnesium alloy and nano-composite%AZ31B镁合金及其纳米复合材料的滑动磨损行为

    Institute of Scientific and Technical Information of China (English)

    M.SRINIVASAN; C.LOGANATHAN; M.KAMARAJ; Q.B.NGUYE; M.GUPTA; R.NARAYANASAMY

    2012-01-01

    AZ31B magnesium alloy and nano-composite were manufactured by hybrid casting process and hot extruded at 350 ℃.The sliding wear behaviour of alloy and nano-composite was estimated at room temperature using the standard pin-on-disc wear test equipment.The tests were conducted under a normal load of 10 N at different sliding speeds ranging from 0.60 to 1.2 m/s for distance up to 2000 m.The wear mechanisms of the wom out surface were studied using SEM analysis.The influence of test parameters on wear rate of the pins was established using a linear regression model statistically.Compared with the AZ31B magnesium alloy,the nano-composite shows lower wear rates due to higher hardness improvement caused by the reinforcement.The wear mechanism appears to be a mix-up of ploughing,rows of furrows,delamination and oxidation.%采用复合铸造工艺制备AZ31B镁合金及其纳米复合材料,再对所得材料在350℃进行热挤压.采用标准的销-盘式摩擦磨损试验机对AZ31B镁合金及其纳米复合材料的室温滑动磨损行为进行研究.实验条件为法向载荷10 N、滑移速度0.60~1.2 m/s、滑移距离2000 m.采用SEM观察来研究磨损表面的磨损机理.通过构建一个线性回归模型来研究试验参数对磨销磨损率的影响.与AZ31B镁合金相比,由于增强体的作用而导致的硬度增强使复合材料表现出低的磨损率.犁削、犁沟、分层和氧化构成混合的磨损机理.

  14. Effect of Casting Parameters on the Microstructural and Mechanical Behavior of Magnesium AZ31-B Alloy Strips Cast on a Single Belt Casting Simulator

    Directory of Open Access Journals (Sweden)

    Ahmad Changizi

    2014-01-01

    Full Text Available Strips of magnesium alloy AZ31-B were cast on a simulator of a horizontal single belt caster incorporating a moving mold system. Mixtures of CO2 and sulfur hexafluoride (SF6 gases were used as protective atmosphere during melting and casting. The castability of the AZ31-B strips was investigated for a smooth, low carbon steel substrate, and six copper substrates with various textures and roughnesses. Graphite powder was used to coat the substrates. The correlation between strip thickness and heat flux was investigated. It was found that the heat flux from the forming strip to the copper substrate was higher than that to the steel substrate, while coated substrates registered lower heat fluxes than uncoated substrates. The highest heat flux from the strip was recorded for casting on macrotextured copper substrates with 0.15 mm grooves. As the thickness of the strip decreased, the net heat flux decreased. As the heat flux increased, the grain sizes of the strips were reduced, and the SDAS decreased. The mechanical properties were improved when the heat flux increased. The black layers which formed on the strips’ surfaces were analyzed and identified as nanoscale MgO particles. Nano-Scale particles act as light traps and appeared black.

  15. Texture evolution in Nd:YAG-laser welds of AZ31 magnesium alloy hot rolled sheets and its influence on mechanical properties

    International Nuclear Information System (INIS)

    Research highlights: → AZ31 LBW fusion zone results in Mg17(Al-Zn)12 precipitation, twins formation and {0 0 2} texture modification. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → A recovery of elongation and UTS can be achieved by a 300 deg. C/1 h heat treatment. The texture evolution is mainly responsible for the yield strength reduction in the fusion zone. - Abstract: AZ31 hot rolled magnesium alloy presents a strong basal texture. Using laser beam welding (LBW) as a joining process induces high temperature gradients leading to major texture changes. Electron back scattered diffraction (EBSD) was used to study the texture evolution, and tensile tests coupled with speckle interferometry were performed to understand its influence on mechanical properties. The random texture obtained in the LBW fusion zone is mainly responsible for the yield strength reduction.

  16. Preferential dynamic recrystallization at original grain boundaries in the hot-rolling process of AZ31 alloy

    International Nuclear Information System (INIS)

    Highlights: ► DRX preferentially occurred at grain boundaries in the hot rolling of AZ31 alloy. ► DRX slightly decreased the starting basal texture of matrix. ► DRX did not follow previous orientation gradient from original matrix. ► DRX orientation was influenced by the localized strain within shearing bands. - Abstract: Single pass hot-rolling was conducted on commercial AZ31 magnesium alloy. Dynamic recrystallization (DRX) preferentially initiated at original grain boundaries in the hot-rolling process, producing the characteristic necklace-like microstructure at higher strain stage. Electron back-scattering diffraction (EBSD) was used to investigate this preferential DRX at grain boundaries. Progressive orientation gradient was found to be involved in subgrain formation, while DRX did not follow previous orientation gradient from matrix and had a tendency to align their (0 0 0 2) plane with shearing plane as they got close to the middle layer of DRX region, which was ascribed to the expanding effect of localized shearing strain.

  17. In vitro degradation, cytocompatibility and hemolysis tests of CaF2 doped TiO2-SiO2 composite coating on AZ31 alloy

    Science.gov (United States)

    Li, Bing; Chen, Yun; Huang, Wei; Yang, Wenzhong; Yin, Xiaoshuang; Liu, Ying

    2016-09-01

    In this study, a CaF2 doped TiO2-SiO2 composite coating was successfully coated onto AZ31 alloy by sol-gel method. Electrochemical tests, in vitro degradation, direct cellular experiment and hemolysis tests were conducted and the results showed that the CaF2 doped TiO2-SiO2 composite coating can not only improve the corrosion resistance, but also enhance the biocompatibility of AZ31 alloy. XRD, SEM and EDX were also performed to characterize the crystalline structures, morphologies and chemical compositions of the coatings.

  18. Effects of carbon dioxide plasma immersion ion implantation on the electrochemical properties of AZ31 magnesium alloy in physiological environment

    Science.gov (United States)

    Xu, Ruizhen; Yang, Xiongbo; Zhang, Xuming; Wang, Mei; Li, Penghui; Zhao, Ying; Wu, Guosong; Chu, Paul K.

    2013-12-01

    Plasma immersion ion implantation (PIII) is conducted to improve the intrinsically poor corrosion properties of biodegradable AZ31 magnesium alloy in the physiological environment. Carbon dioxide is implanted into the samples and X-ray photoelectron spectroscopy and scanning electron microscopy are used to characterize the materials. The corrosion properties are systematically studied by potentiodynamic polarization tests in two simulated physiological environments, namely simulated body fluids and cell culture medium. The plasma-implanted materials exhibit a lower initial corrosion rate. Being a gaseous ion PIII technique, conformal ion implantation into an object with a complex shape such as an orthopedic implant can be easily accomplished and CO2 PIII is a potential method to improve the biological properties of magnesium and its alloys in clinical applications.

  19. Effects of carbon dioxide plasma immersion ion implantation on the electrochemical properties of AZ31 magnesium alloy in physiological environment

    International Nuclear Information System (INIS)

    Plasma immersion ion implantation (PIII) is conducted to improve the intrinsically poor corrosion properties of biodegradable AZ31 magnesium alloy in the physiological environment. Carbon dioxide is implanted into the samples and X-ray photoelectron spectroscopy and scanning electron microscopy are used to characterize the materials. The corrosion properties are systematically studied by potentiodynamic polarization tests in two simulated physiological environments, namely simulated body fluids and cell culture medium. The plasma-implanted materials exhibit a lower initial corrosion rate. Being a gaseous ion PIII technique, conformal ion implantation into an object with a complex shape such as an orthopedic implant can be easily accomplished and CO2 PIII is a potential method to improve the biological properties of magnesium and its alloys in clinical applications.

  20. Evaluation of the anti-corrosive effect of acid pickling and sol-gel coating on magnesium AZ31 alloy

    International Nuclear Information System (INIS)

    The effect of different acid pre-treatment procedures on the corrosion of magnesium AZ31 alloy was compared by measuring the amount of hydrogen gas formed when the surface was in contact with aqueous 5% sodium chloride solution. A 4-7 μm thick sol-gel coating prepared by phosphoric acid catalyzed sol-gel processing of a methyltriethoxysilane/tetraethoxysilane mixture was applied to the differently pre-treated magnesium surfaces. The corrosion rate of the alloy decreased by a factor of up to 60 by combination of acid pickling and sol-gel coating. The addition of triethylphosphate or 1,2,4-triazole as corrosion inhibitors led to further improvements. Composition and texture of the films was investigated by scanning electron microscopy and energy dispersive X-ray analysis

  1. Fusion welding of Fe-added lap joints between AZ31B magnesium alloy and 6061 aluminum alloy by hybrid laser-tungsten inert gas welding technique

    International Nuclear Information System (INIS)

    Highlights: → Hybrid Laser-TIG fusion welding technique was used for joining Mg to Al alloys. → Laser defocusing amount determined penetration depth inside Al alloy of joints. → The addition of Fe interlayer suppressed Mg-Al intermetallics greatly in joints. → A maximum joint strength with optimum thickness of Fe interlayer was obtained. → Excessive addition of Fe interlayer was adverse for the strength improvement. -- Abstract: AZ31B magnesium alloy and 6061-T6 aluminum alloy were lap joined together with the addition of Fe interlayer by fusion welding of hybrid laser-tungsten inert gas (TIG) technique. The influence of location of laser focal spot (LFS) on joint penetration depth and that of the depth on joint strength were investigated. The results showed that when the LFS was just on the surface of Al plate, the deepest penetration could be obtained, which contributed to the improvement of shear strength of Fe-added joints, but not to the elevation of the strength of Mg/Al direct joints. The addition of Fe interlayer suppressed massive production of Mg-Al intermetallics but produced Fe-Al intermetallics in the fusion zone of the joints, whose micro-hardness was extremely high and was also adverse for the enhancement of joint shear strength. The effect of Fe-interlayer thickness on the joint shear strength was also examined, and the maximum shear strength of Fe-added joint could achieve 100 MPa with 0.13 mm thick Fe interlayer. The fracture modes of 0.07 and 0.13 mm Fe-interlayer-added joints were both quasi-cleavage, while those of direct and 0.22 mm interlayer-added joints were completely cleavage. The theoretical shear strength of the Fe-added joints was also discussed.

  2. Ram speed profile design for isothermal extrusion of AZ31 magnesium alloy by using FEM simulation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the conventional hot extrusion of metallic materials,the temperature of the workpiece varies during the whole extrusion process,leading to the non-uniformity of the product dimension,microstructure and properties.In the present research,a simulation model based on the principle of PID control was developed to establish ram speed profiles that can suppress the temperature evolution during the process to allow for isothermaI extrusion.With this simulation model,the real-time extrusion ram speed was adjusted according to the simulated exit temperature.The results show that temperature homogeneity is significantly improved not only along the extrudate length but also on its cross section in the case of extrusion in the isothermal mode with a designed ram speed profile in the extrusion process of AZ31 magnesium.In addition,die temperature varies over a more narrow range in comparison with extrusion in the conventional iso-speed mode.

  3. Research on backward extrusion for AZ31 magnesium alloy based on servo press%基于伺服压力机的AZ31镁合金反挤压成形

    Institute of Scientific and Technical Information of China (English)

    程永奇; 郭强; 刘易凡; 许仕宁

    2012-01-01

    为探讨挤压速度模式对AZ31镁合金杯形件反挤压成形的影响,对伺服压力机反挤压成形进行有限元分析与实验,并与普通曲柄压力机和液压机反挤压成形进行比较.有限元分析结果表明,反挤压终了阶段,伺服挤压和液压挤压最大损伤值分别为3.41和3.30,远低于普通挤压的最大损伤值6.08;挤压过程中杯形件最大温差伺服挤压为45℃,而普通挤压和液压挤压分别为127℃和70℃.实验结果表明,在1100kN伺服压力机上,采用伺服挤压模式,可成功获得壁厚为3mm的AZ31镁合金反挤压杯形件,而采用普通挤压模式,在杯形件边缘则出现破裂.实验与有限元分析结果基本吻合.%In order to explore the effect of the velocity mode on backward extrusion forming of AZ31 magnesium alloy cup, the finite element method and experiment were used to analyze the procedure on servo press, which was compared with the forming on ordinary crank press and hydraulic press. The results of finite element analysis indicated that the maximum damage of backward extrusion for servo press and hydraulic press at the final forming stage were 3. 41 and 3. 30 respectively, which were lower than 6. 08 for ordinary crank press. The maximum difference temperature was only 45*C for servo press, 127℃ for ordinary crank press and 70 ℃ for hydraulic press. The experimental results proved that the backward extrusion cup of AZ31 magnesium alloy with the thickness of 3mm could be formed under the 1100kN servo press, while the fracture appeared at the flange under the ordinary crank press. The experimental results were agreed with the numerical results.

  4. Role of biomineralization on the degradation of fine grained AZ31 magnesium alloy processed by groove pressing

    International Nuclear Information System (INIS)

    Groove pressing (GP) has been successfully adopted to achieve fine grain size up to 7 μm in AZ31 magnesium alloy with an initial grain size of 55 μm. The effect of microstructural evolution and surface features on wettability, corrosion resistance, bioactivity and cell adhesion were investigated with an emphasis to study the influence of deposited phases when the samples were immersed in simulated body fluid (SBF 5 ×). The role of microstructure was also evaluated without any surface treatments or coatings on the material. GPed samples exhibit improved hydrophilicity compared to the annealed sample. After immersion in SBF, specimens were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD) methods. More amount of white precipitates composed of hydroxyapatite and magnesium phosphate along with magnesium hydroxide was observed on the surfaces of groove pressed specimens as compared to the annealed specimens with an increase in immersion time in SBF. Corrosion behavior of the samples estimated using potentiodynamic polarization curves indicate good corrosion resistance for GPed samples before and after immersion in SBF. The MTT assay using rat skeletal muscle (L6) cells revealed that both the processed and unprocessed samples are nontoxic and cell adhesion was promising for GPed sample. - Highlights: ► Fine grain structure was achieved in AZ31 magnesium alloy by groove pressing. ► Influence of microstructure and surface roughness on surface energy and biomineralization was studied. ► Early biomineralization due to high wettability reduced the degradation rate in groove pressed samples. ► Better cell viability and adhesion due to surface micro-features induced by groove pressing were observed

  5. Role of biomineralization on the degradation of fine grained AZ31 magnesium alloy processed by groove pressing

    Energy Technology Data Exchange (ETDEWEB)

    Sunil, B. Ratna [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036 (India); Kumar, Arun Anil [Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli, 620015 (India); Sampath Kumar, T.S., E-mail: tssk@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036 (India); Chakkingal, Uday [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036 (India)

    2013-04-01

    Groove pressing (GP) has been successfully adopted to achieve fine grain size up to 7 μm in AZ31 magnesium alloy with an initial grain size of 55 μm. The effect of microstructural evolution and surface features on wettability, corrosion resistance, bioactivity and cell adhesion were investigated with an emphasis to study the influence of deposited phases when the samples were immersed in simulated body fluid (SBF 5 ×). The role of microstructure was also evaluated without any surface treatments or coatings on the material. GPed samples exhibit improved hydrophilicity compared to the annealed sample. After immersion in SBF, specimens were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD) methods. More amount of white precipitates composed of hydroxyapatite and magnesium phosphate along with magnesium hydroxide was observed on the surfaces of groove pressed specimens as compared to the annealed specimens with an increase in immersion time in SBF. Corrosion behavior of the samples estimated using potentiodynamic polarization curves indicate good corrosion resistance for GPed samples before and after immersion in SBF. The MTT assay using rat skeletal muscle (L6) cells revealed that both the processed and unprocessed samples are nontoxic and cell adhesion was promising for GPed sample. - Highlights: ► Fine grain structure was achieved in AZ31 magnesium alloy by groove pressing. ► Influence of microstructure and surface roughness on surface energy and biomineralization was studied. ► Early biomineralization due to high wettability reduced the degradation rate in groove pressed samples. ► Better cell viability and adhesion due to surface micro-features induced by groove pressing were observed.

  6. Effect of calcium content on the microstructural evolution and mechanical properties of wrought Mg-3Al-1Zn alloy

    International Nuclear Information System (INIS)

    The effect of Ca element on the hot workability and microstructure evolution of AZ31 magnesium alloy was investigated. Conventional AZ31, AZ31 + 0.7 wt.%Ca, and AZ31 + 2.0 wt.%Ca alloys were tested. Electron back scattered diffraction microscopy revealed that the alloys containing Ca exhibited much finer and more homogeneous microstructure than the conventional AZ31 alloy. Hot compression and tensile tests showed that the Ca element generally increased flow strength and decreased ductility at low temperature. High temperature elongation was considerably improved by the operation of the thermally activated process. TEM work suggested that the large volume fraction of fine (Mg, Al)2Ca particles played an important role in preventing significant grain growth of the AZ31 + 2.0Ca alloy.

  7. Surface Protection of Friction Stir Welding Joint for AZ31 Magnesium Alloy Coated by Microarc Oxidation%AZ31镁合金搅拌摩擦焊接头微弧氧化表面防护研究

    Institute of Scientific and Technical Information of China (English)

    薛文斌; 陈廷芳; 李永良; 邹志锋; 刘晓龙; 赵衍华

    2012-01-01

    A uniform ceramic coating on friction stir welding (FSW) joint of AZ31 magnesium alloy was fabricated by microarc oxidation (MAO) in silicate electrolyte. Microstructure, phase constituent and microhardness profile of the MAO coating at the different zones of FSW joint were analyzed. The influence of microarc oxidation surface treatment on corrosion behaviors of FSW joint was evaluated by immersion and potentiodynamic polarization tests. The results show that hardness of stir zone is higher than that of base alloy, but the hardness of heat-affected zone is lower than that of base alioy. However, the microhardness of MAO coating at different zones of FSW joint is the same, which is about seven times higher than that of AZ31 base alloy. After immersion test in 3. 5%NaCl(mass fraction) solution, the serious pitting corrosion on heat-affected zone takes place, but no pitting corrosion is observed on the MAO coating surface. In addition, the heat-affected zone of FSW joint has a lower corrosion potential and higher corrosion current density, but the corrosion current density of MAO coating at different zones is very close, which is much lower than that of bare AZ31 magnesium alloy. So the MAO surface treatment can significantly improve the corrosion resistance of FSW joint of AZ31 magnesium alloy.%在硅酸盐溶液中于AZ31镁合金搅拌摩擦焊接头表面制备一层均匀的微弧氧化膜.分析微弧氧化膜的截面组织、相组成和显微硬度分布,并采用浸泡和电化学方法评估微弧氧化表面处理对焊接接头腐蚀行为的影响.结果表明:接头搅拌区的显微硬度高于镁合金母相区,热影响区硬度低于母相区,但接头不同区域对应的微弧氧化膜硬度都相同,比镁合金基体提高约7倍.在3.5% NaCl溶液中浸泡后,焊接样品热影响区腐蚀严重,而微弧氧化膜表面形貌没有明显变化.未表面处理的接头热影响区电位低于搅拌区和母相区,其腐蚀电流密度也较

  8. The effect of sodium silicate concentration on microstructure and corrosion properties of MAO-coated magnesium alloy AZ31 in simulated body fluid

    OpenAIRE

    B. Salami; Afshar, A.; Mazaheri, A.

    2014-01-01

    In recent years, magnesium and its alloys are considered as biodegradable implants. However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed. In this investigation, micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid. Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current. The effects of silicate concentration and conductivity...

  9. Constitutive Equations and Flow Behavior of an As-Extruded AZ31 Magnesium Alloy Under Large Strain Condition

    Science.gov (United States)

    Dong, Yuanyuan; Zhang, Cunsheng; Lu, Xing; Wang, Cuixue; Zhao, Guoqun

    2016-06-01

    A reasonable constitutive model is the key to achieving the accurate numerical simulation of magnesium alloy extrusion process. Based on the hot compression tests of the as-extruded AZ31 magnesium alloy, the strain-compensated Arrhenius equation, the constitutive equation taking into account dynamic recovery (DRV) and dynamic recrystallization (DRX), and the modified Fields-Backofen equation (FB) are established to describe the deformation behavior of this alloy under large strain condition (strain level greater than 1.0) and wide strain rate range (0.01 to 10 s-1), respectively. Then material parameters in each constitutive model are determined by linear fitting method. The comparison of these three kinds of equations shows that the strain-compensated Arrhenius model provides the best prediction of flow stress, and the calculated value of correlation coefficient ( R) is the highest as 0.9945 and the average absolute relative error (AARE) is the lowest as 3.11%. The constitutive equation with DRV + DRX can also predict flow stress accurately, and its values of R and AARE are 0.9920 and 4.41%, respectively. However, compared to the other two constitutive equations, the modified FB equation does not give good description of hot deformation behavior for this magnesium alloy. Finally, the advantages and drawbacks of these three kinds of constitutive models are discussed and compared. Therefore, this work could provide theoretical guidelines for investigating hot deformation behavior of wrought magnesium alloys and determining the appropriate extrusion process parameters under large strain condition.

  10. Influence of Microstructure of Friction Stir Welded Joints on Growth and Properties of Microarc Oxidation Coatings on AZ31B Magnesium Alloy

    Science.gov (United States)

    Chen, Tingfang; Li, Yongliang; Xue, Wenbin; Yang, Chaolin; Qu, Yao; Hua, Ming

    2015-03-01

    Ceramic coatings on friction stir welded (FSW) joints of AZ31B magnesium alloy were fabricated by microarc oxidation (MAO) method in silicate electrolyte. Microstructure, phase constituents, microhardness and electrochemical corrosion behaviors of bare and coated magnesium alloys at different zones of FSW joints for different oxidation time were investigated. The influence of microstructure at different zones on the growth of MAO coatings was analyzed. The results show that the MAO coatings on FSW joints are uniform, and they have almost the same morphology, phase constituents, hardness and corrosion resistance at base metal, stir zone and heat-affected zone. The properties of MAO coatings are independent on the microstructures of AZ31B alloy. In addition, the microstructures of magnesium alloy near the coating/alloy interface at different zones of FSW joint was not changed by microarc discharge process.

  11. Effect of interlayer configurations on joint formation in TLP bonding of Ti-6Al-4V to Mg-AZ31

    International Nuclear Information System (INIS)

    In this research work, the transient liquid phase (TLP) bonding process was utilized to fabricate joints using thin (20μm) nickel and copper foils placed between two bonding surfaces to help facilitate joint formation. Two joint configurations were investigated, first, Ti-6Al-4V/CuNi/Mg-AZ31 and second, Ti-6Al-4V/NiCu/Mg-AZ3L The effect of bonding time on microstructural developments across the joint and the changes in mechanical properties were studied as a function of bonding temperature and pressure. The bonded specimens were examined by metallographic analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD). In both cases, intermetallic phase of CuMg2 and Mg3AlNi2 was observed inside the joint region. The results show that joint shear strengths for the Ti-6Al-4V/CuNi/Mg-AZ31 setup produce joints with shear strength of 57 MPa compared to 27MPa for joints made using the Ti-6Al-4V/NiCu/Mg-AZ31 layer arrangement

  12. Improving corrosion resistance of AZ31B magnesium alloy via a conversion coating produced by a protic ammonium-phosphate ionic liquid

    International Nuclear Information System (INIS)

    Magnesium alloys are susceptible to corrosion because of their high reactivity and low electrode potential. The present work introduces a conversion coating using a protic ammonium-phosphate ionic liquid (IL). Initial results on the AZ31B Mg alloy have demonstrated substantially improved corrosion resistance for the IL treatment at 300 °C (IL300C) compared to the treatment at room temperature. Potentiodynamic polarization analysis of the IL300C treated Mg surface in a NaCl solution exhibited a strong passivation behavior. No pretreatment is needed and the treated surface morphology is well preserved. Cross-sectional nanostructure examination using transmission electron microscopy and element mapping using energy-dispersive X-ray spectroscopy have revealed the IL300C conversion coating to be a 70–80 nm thick with a two-layer structure. Further surface chemical analysis using X-ray photoelectron spectroscopy suggested such an IL conversion coating possibly composed of metal oxides, metal phosphates, and carbonaceous compounds. - Highlights: • Anti-corrosion conversion film for Mg by a protic ammonium-phosphate ionic liquid • No pretreatment needed and no change in surface appearance and morphology • The ionic liquid conversion film of 70–80 nm thick and a two-layer structure

  13. INFLUENCE OF MICROSTRUCTURE OF FRICTION STIR WELDED JOINTS ON GROWTH AND PROPERTIES OF MICROARC OXIDATION COATINGS ON AZ31B MAGNESIUM ALLOY

    OpenAIRE

    TINGFANG CHEN; YONGLIANG LI; WENBIN XUE; CHAOLIN YANG; YAO QU; MING HUA

    2015-01-01

    Ceramic coatings on friction stir welded (FSW) joints of AZ31B magnesium alloy were fabricated by microarc oxidation (MAO) method in silicate electrolyte. Microstructure, phase constituents, microhardness and electrochemical corrosion behaviors of bare and coated magnesium alloys at different zones of FSW joints for different oxidation time were investigated. The influence of microstructure at different zones on the growth of MAO coatings was analyzed. The results show that the MAO coatings o...

  14. A study on the relationships between corrosion properties and chemistry of thermally oxidised surface films formed on polished commercial magnesium alloys AZ31 and AZ61

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, Sebastián, E-mail: sfeliu@cenim.csic.es [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Samaniego, Alejandro [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Barranco, Violeta [Instituto de Ciencias de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Científicas, CSIC, Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049, Madrid (Spain); El-Hadad, A.A. [Physics Department, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo (Egypt); Llorente, Irene [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Serra, Carmen [Servicio de Nanotecnologia y Análisis de Superficies, CACTI, Universidade de Vigo, 36310 Vigo (Spain); Galván, J.C. [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2014-03-01

    Highlights: • Surface chemistry of heat treated magnesium alloys. • Relation between heat treatment and aluminium subsurface enrichment. • Relation between surface composition and corrosion behaviour. - Abstract: This paper studies the changes in chemical composition of the thin oxide surface films induced by heating in air at 200 °C for time intervals from 5 min to 60 min on the freshly polished commercial AZ31 and AZ61 alloys with a view to better understanding their protective properties. This thermal treatment resulted in the formation of layers enriched in metallic aluminium at the interface between the outer MgO surface films and the bulk material. A strong link was found between the degree of metallic Al enrichment in the subsurface layer (from 10 to 15 at.%) observed by XPS (X-ray photoelectron spectroscopy) in the AZ61 treated samples and the increase in protective properties observed by EIS (electrochemical impedance spectroscopy) in the immersion test in 0.6 M NaCl. Heating for 5–60 min in air at 200 °C seems to be an effective, easy to perform and inexpensive method for increasing the corrosion resistance of the AZ61 alloy by approximately two or three times.

  15. The effect of sodium silicate concentration on microstructure and corrosion properties of MAO-coated magnesium alloy AZ31 in simulated body fluid

    Directory of Open Access Journals (Sweden)

    B. Salami

    2014-03-01

    Full Text Available In recent years, magnesium and its alloys are considered as biodegradable implants. However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed. In this investigation, micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid. Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current. The effects of silicate concentration and conductivity of electrolyte solution on microstructure and corrosion properties of coating were evaluated. Scanning electron microscopy showed that a thick and condensed coating is formed after enough anodizing period. Energy dispersive spectroscopy showed that Si, O and Mg are the main components of the coating. Corrosion resistance of the coated and uncoated samples was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy tests in SBF at 37 °C and pH of 7.4. Maximum corrosion resistance was achieved at 30 g/L concentration of sodium silicate in anodizing solution. It was observed that further increase in silicate concentration decreased the corrosion resistance.

  16. Cold metal transfer welding–brazing of pure titanium TA2 to magnesium alloy AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Cao, R., E-mail: caorui@lut.cn; Wang, T.; Wang, C.; Feng, Z.; Lin, Q.; Chen, J.H.

    2014-08-25

    Highlights: • Mg–Ti joints can be successfully performed at suitable welding variables by CMT. • Typical brazing–welding joints can be formed for Mg–Ti joint and Ti–Mg joint. • The brazing interface is mainly composed of Ti{sub 3}Al, Mg{sub 17}Al{sub 12} and Mg{sub 0.97}Zn{sub 0.03}. • Elements Al and Zn are crucial to join successfully Mg and Ti base metals. - Abstract: Pure titanium TA2 was joined to Mg AZ31B by cold metal transfer (CMT) welding–brazing method in the form of two lap-shear joints (Mg–Ti joint and Ti–Mg joint) with Mg AZ61 wire. The microstructure of Ti/Mg CMT joints was identified and characterized by means of optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties of various welding parameters were compared and analyzed. Desired Ti/Mg CMT joints with satisfied weld appearances and mechanical properties were achieved at suitable welding variables. The Ti/Mg CMT joints had dual characteristics of a welding joint at the Mg side and a brazing joint at the Ti side. Moreover, for two joints, the brazing interfaces were composed of an intermetallic compounds (IMCs) layer including Ti{sub 3}Al, Mg{sub 17}Al{sub 12} and Mg{sub 0.97}Zn{sub 0.03} phases. Mg–Ti joint had the higher tensile load of 2.10 kN, and Ti–Mg joint had the tensile load of 1.83 kN.

  17. Cold metal transfer welding–brazing of pure titanium TA2 to magnesium alloy AZ31B

    International Nuclear Information System (INIS)

    Highlights: • Mg–Ti joints can be successfully performed at suitable welding variables by CMT. • Typical brazing–welding joints can be formed for Mg–Ti joint and Ti–Mg joint. • The brazing interface is mainly composed of Ti3Al, Mg17Al12 and Mg0.97Zn0.03. • Elements Al and Zn are crucial to join successfully Mg and Ti base metals. - Abstract: Pure titanium TA2 was joined to Mg AZ31B by cold metal transfer (CMT) welding–brazing method in the form of two lap-shear joints (Mg–Ti joint and Ti–Mg joint) with Mg AZ61 wire. The microstructure of Ti/Mg CMT joints was identified and characterized by means of optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties of various welding parameters were compared and analyzed. Desired Ti/Mg CMT joints with satisfied weld appearances and mechanical properties were achieved at suitable welding variables. The Ti/Mg CMT joints had dual characteristics of a welding joint at the Mg side and a brazing joint at the Ti side. Moreover, for two joints, the brazing interfaces were composed of an intermetallic compounds (IMCs) layer including Ti3Al, Mg17Al12 and Mg0.97Zn0.03 phases. Mg–Ti joint had the higher tensile load of 2.10 kN, and Ti–Mg joint had the tensile load of 1.83 kN

  18. Multi-passes warm rolling of AZ31 magnesium alloy, effect on evaluation of texture, microstructure, grain size and hardness

    International Nuclear Information System (INIS)

    In this study the effect of multi-passes warm rolling of AZ31 magnesium alloy on texture, microstructure, grain size variation and hardness of as cast sample (A) and two rolled samples (B and C) taken from different locations of the as-cast ingot was investigated. The purpose was to enhance the formability of AZ31 alloy in order to help manufacturability. It was observed that multi-passes warm rolling (250 degree C to 350 degree C) of samples B and C with initial thickness 7.76mm and 7.73 mm was successfully achieved up to 85% reduction without any edge or surface cracks in ten steps with a total of 26 passes. The step numbers 1 to 4 consist of 5, 2, 11 and 3 passes respectively, the remaining steps 5 to 10 were single pass rolls. In each discrete step a fixed roll gap is used in a way that true strain per step increases very slowly from 0.0067 in the first step to 0.7118 in the 26th step. Both samples B and C showed very similar behavior after 26th pass and were successfully rolled up to 85% thickness reduction. However, during 10th step (27th pass) with a true strain value of 0.772 the sample B experienced very severe surface as well as edge cracks. Sample C was therefore not rolled for the 10th step and retained after 26 passes. Both samples were studied in terms of their basal texture, microstructure, grain size and hardness. Sample C showed an equiaxed grain structure after 85% total reduction. The equiaxed grain structure of sample C may be due to the effective involvement of dynamic recrystallization (DRX) which led to formation of these grains with relatively low misorientations with respect to the parent as cast grains. The sample B on the other hand showed a microstructure in which all the grains were elongated along the rolling direction (RD) after 90 % total reduction and DRX could not effectively play its role due to heavy strain and lack of plastic deformation systems. The microstructure of as cast sample showed a near-random texture (mrd 4.3), with

  19. Multi-passes warm rolling of AZ31 magnesium alloy, effect on evaluation of texture, microstructure, grain size and hardness

    International Nuclear Information System (INIS)

    In this study the effect of multi-passes warm rolling of AZ31 magnesium alloy on texture, microstructure, grain size variation and hardness of as cast sample (A) and two rolled samples (B and C) taken from different locations of the as-cast ingot was investigated. The purpose was to enhance the formability of AZ31 alloy in order to help manufacturability. It was observed that multi-passes warm rolling (250°C to 350°C) of samples B and C with initial thickness 7.76mm and 7.73 mm was successfully achieved up to 85% reduction without any edge or surface cracks in ten steps with a total of 26 passes. The step numbers 1 to 4 consist of 5, 2, 11 and 3 passes respectively, the remaining steps 5 to 10 were single pass rolls. In each discrete step a fixed roll gap is used in a way that true strain per step increases very slowly from 0.0067 in the first step to 0.7118 in the 26th step. Both samples B and C showed very similar behavior after 26th pass and were successfully rolled up to 85% thickness reduction. However, during 10th step (27th pass) with a true strain value of 0.772 the sample B experienced very severe surface as well as edge cracks. Sample C was therefore not rolled for the 10th step and retained after 26 passes. Both samples were studied in terms of their basal texture, microstructure, grain size and hardness. Sample C showed an equiaxed grain structure after 85% total reduction. The equiaxed grain structure of sample C may be due to the effective involvement of dynamic recrystallization (DRX) which led to formation of these grains with relatively low misorientations with respect to the parent as cast grains. The sample B on the other hand showed a microstructure in which all the grains were elongated along the rolling direction (RD) after 90 % total reduction and DRX could not effectively play its role due to heavy strain and lack of plastic deformation systems. The microstructure of as cast sample showed a near-random texture (mrd 4.3), with average grain

  20. Improvement in Cold Formability of AZ31 Magnesium Alloy Sheets Processed by Equal Channel Angular Pressing (ECAP)

    OpenAIRE

    Suh, Joung Sik

    2016-01-01

    The present study contributes to enhance the cold formability and competitiveness of magnesium sheet AZ31 as lightweight material using the process equal channel angular pressing (ECAP). The systematic parameter study of ECAP process leads to a fundamental understanding of the interactions between microstructure and texture evolution, activation of deformation mechanisms and mechanical properties of AZ31 sheets. On this basis, the fundamentals are established in order that ECAP process can be...

  1. Effect of current frequency on the mechanical properties, microstructure and texture evolution in AZ31 magnesium alloy strips during electroplastic rolling

    International Nuclear Information System (INIS)

    The effect of electroplastic rolling (ER) on the mechanical properties, microstructure and texture in the AZ31 magnesium alloy strips has been investigated by tensile testing and electron back scattered diffraction (EBSD) methods. It is shown that the mechanical properties, microstructure, and texture are highly current frequency-dependent. Best mechanical properties are obtained from the 500 Hz ER specimen by carrying out tensile tests for all the rolled strips. Besides, the frequencies of twin boundaries, which are reduced to the minimum at 500 Hz, vary with the current frequency. Moreover, it can be seen from the calculated (0001) and (101¯0) pole figures that texture evolved into an obvious off-basal texture, and non-basal slip systems are activated under 500 Hz. The mechanisms of twinning growth and texture evolution in AZ31 magnesium alloy strips during ER are considered to be responsible for the experimental results

  2. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  3. Characterization of High Strain Rate Mechanical behavior of AZ31 magnesium alloy using 3D Digital Image Correlation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanli [ORNL; Xu, Hanbing [ORNL; ERDMAN III, DONALD L [ORNL; Starbuck, J Michael [ORNL; Simunovic, Srdjan [ORNL

    2011-01-01

    Characterization of the material mechanical behavior at sub-Hopkinson regime (0.1 to 1000 s{sup -1}) is very challenging due to instrumentation limitations and the complexity of data analysis involved in dynamic loading. In this study, AZ31 magnesium alloy sheet specimens are tested using a custom designed servo-hydraulic machine in tension at nominal strain rates up to 1000 s{sup -1}. In order to resolve strain measurement artifacts, the specimen displacement is measured using 3D Digital Image correlation instead from actuator motion. The total strain is measured up to {approx} 30%, which is far beyond the measurable range of electric resistance strain gages. Stresses are calculated based on the elastic strains in the tab of a standard dog-bone shaped specimen. Using this technique, the stresses measured for strain rates of 100 s{sup -1} and lower show little or no noise comparing to load cell signals. When the strain rates are higher than 250 s{sup -1}, the noises and oscillations in the stress measurements are significantly decreased from {approx} 250 to 50 MPa. Overall, it is found that there are no significant differences in the elongation, although the material exhibits slight work hardening when the strain rate is increased from 1 to 100 s{sup -1}.

  4. Characterization of high-strain rate mechanical behavior of AZ31 magnesium alloy using 3D digital image correlation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yanli; Xu, Hanbing; Erdman, Donald L.; Starbuck, Michael J.; Simunovic, Srdjan [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2011-10-15

    Characterization of the material mechanical behavior at sub-Hopkinson regime (0.1 to 1 000 s{sup -1}) is very challenging due to instrumentation limitations and the complexity of data analysis involved in dynamic loading. In this study, AZ31 magnesium alloy sheet specimens are tested using a custom designed servo-hydraulic machine in tension at nominal strain rates up to 1 000 s{sup -1}. In order to resolve strain measurement artifacts, the specimen displacement is measured using 3D Digital Image correlation instead from actuator motion. The total strain is measured up to {approx} 30%, which is far beyond the measurable range of electric resistance strain gages. Stresses are calculated based on the elastic strains in the tab of a standard dog-bone shaped specimen. Using this technique, the stresses measured for strain rates of 100 s{sup -1} and lower show little or no noise comparing to load cell signals. When the strain rates are higher than 250 s{sup -1}, the noises and oscillations in the stress measurements are significantly decreased from {approx} 250 to 50 MPa. Overall, it is found that there are no significant differences in the elongation, although the material exhibits slight work hardening when the strain rate is increased from 1 to 100 s{sup -1}. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    Science.gov (United States)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  6. In vitro degradation of AZ31 magnesium alloy coated with nano TiO2 film by sol-gel method

    International Nuclear Information System (INIS)

    A nano TiO2 film was coated on AZ31 alloy substrate by sol-gel method. The TiO2 film was characterized by X-ray diffractometry (XRD), differential scanning calorimetry-thermogravimetric analysis (DSC-TG), field emission scanning electron microscopy (FE-SEM) and energy dispersion spectroscopy (EDS). The degradation of the nano-TiO2 coated alloy was evaluated by immersion test and electrochemical measurement. An attempt was made to relate corrosion of coated alloys with the annealing treatment and resultant structural evolution.

  7. Effects of rare earth elements and Ca additions on high temperature mechanical properties of AZ31 magnesium alloy processed by ECAP

    International Nuclear Information System (INIS)

    High temperature mechanical properties of equal channel angularly pressed (ECAPed) AZ31 magnesium alloy with 0.6%RE, 0.6%Ca and 0.3%RE-0.3%Ca additions were investigated. After extruding, the materials were ECAPed for 4 passes using route BC. Due to the textural effects induced by ECAP, the flow stress of the ECAPed AZ31 was lower than that of the extruded alloy at 523 K while tensile ductility was not changed. Thermal stability of the grain structure was achieved by RE-and Ca-containing particles, mainly due to the suppression of grain growth. Addition of the RE elements and calcium increased tensile strength mainly by dispersive strengthening effects of particles. The improved tensile ductility of the extruded material, however, was achieved by the presence of stable fine grains. Among all tested materials, AZ31-0.6%RE showed the maximum ductility of 198% at 523 K and a strain rate of 10-4 s-1.

  8. Study on laser surface remelting of plasma-sprayed Al–Si/1 wt% nano-Si3N4 coating on AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Plasma sprayed micro-structured Al–Si based and 1 wt% nano-structured Si3N4 coating was successfully fabricated on an AZ31B magnesium alloy using a high efficiency supersonic atmosphere plasma spraying system, and then the as-sprayed coating was remelted by a continuous wave CO2 laser. The remelted coating was investigated by optical microscope, scanning electron microscope, energy-dispersive spectroscopy, X-ray diffractometer and Vickers microhardness tester. The results indicated that the laser remelted coating possessed an excellent metallurgical bonding to the substrate. A finer dendritic structure was exhibited after laser remelting. The nano-Si3N4 decomposed fully in the coating, and the remelted coating was mainly composed of Al, AlN, Al9Si, Al3.21Si0.47 and Mg2Si. Moreover, the microhardness of remelted coating was enhanced to 200–514HV0.05, which was much higher than that of the substrate(about 50 HV0.05).

  9. Nanomechanical analysis of AZ31 magnesium alloy and pure magnesium correlated with crystallographic orientation

    Czech Academy of Sciences Publication Activity Database

    Bočan, Jiří; Maňák, Jan; Jäger, Aleš

    2015-01-01

    Roč. 644, Sep (2015), s. 114-120. ISSN 0921-5093 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : EBSD * electron microscopy * hardness measurement * magnesium alloy s * mechanical characterization * nanoindentation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.567, year: 2014

  10. FORMATION OF HA-CONTAINING COATING ON AZ31 MAGNESIUM ALLOY BY MICRO-ARC OXIDATION

    OpenAIRE

    HUI TANG; DEYU LI; XIUPING CHEN; CHAO WU; FUPING WANG

    2013-01-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this study, a HA-containing coating was fabricated by micro-arc oxidation (MAO). The active plasma species of micro-discharge was studied by optical emission spectroscopy (OES). The microstructure and composition were analyzed by scanning electron microscopy (SEM) and X-ray ...

  11. Evaluation of the Quality of Coatings Deposited on AZ31 Magnesium Alloy Using the Anodising Method / Ocena Jakości Powłok Wykonanych Na Stopie Magnezu Az31 Metodą Anodowania

    Directory of Open Access Journals (Sweden)

    Wieczorek J.

    2015-12-01

    Full Text Available The paper presents results of a study on the quality of coatings deposited on surfaces of AZ31 magnesium alloy products. In order to obtain protective coatings (corrosion and erosive wear protection, the methods of anodising (specimens A, B and C and, for comparison, electroless plating (specimen D were applied. The assessment of coating quality was based on the scratch test results. The results were used for determination of critical loads resulting in coating rupture. The best result was obtained for the specimen B (sulphuric acid anodising in combination with sealing: the critical load was 7.5 N. The smallest value (5.5 N was observed for the specimen D, i.e. the coating produced using the electroless plating method. Moreover, erosion resistance of the coatings was assessed. In this case, a depth of the wear trace due to an erodent agent (SiC powder effects was investigated. The results are comparable to those obtained in the scratch test. The poorest erosion resistance is demonstrated by the coating D and the best resistance is observed for the coating B.

  12. Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, J. [Department of Materials Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran 141554933 (Iran, Islamic Republic of); Behnamian, Y. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Mostafaei, A., E-mail: amir.mostafaei@gmail.com [Young Researchers and Elites Club, Tehran North Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Izadi, H. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Saeid, T. [Faculty of Materials Engineering, Sahand University of Technology, Tabriz 513351996 (Iran, Islamic Republic of); Kokabi, A.H. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran 113659466 (Iran, Islamic Republic of); Gerlich, A.P., E-mail: adrian.gerlich@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2015-03-15

    Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

  13. Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

    International Nuclear Information System (INIS)

    Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al12Mg17 (γ) and Al3Mg2 (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al12Mg17 (γ) and Al3Mg2 (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic compounds • Microstructure and chemical studies

  14. Dynamic behavior and constitutive modeling of magnesium alloys AZ91D and AZ31B under high strain rate compressive loading

    Science.gov (United States)

    Xiao, Jing; Ahmad, Iram Raza; Shu, D. W.

    2014-03-01

    The dynamic stress-strain characteristics of magnesium alloys have not been sufficiently studied experimentally. Thus, the present work investigated compressive dynamic stress-strain characteristics of two representative magnesium alloys: AZ91D and AZ31B at high strain rates and elevated temperatures. In order to use the stress-strain characteristics in numerical simulations to predict the impact response of components, the stress-strain characteristics must be modeled. The most common approach is to use accepted constitutive laws. The results from the experimental study of the response of magnesium alloys AZ91D and AZ31B under dynamic compressive loading, at different strain rates and elevated temperatures are presented here. Johnson-Cook model was used to best fit the experimental data. The material parameters required by the model were obtained and the resultant stress-strain curves of the two alloys for each testing condition were plotted. It is found that the dynamic stress-strain relationship of both magnesium alloys are strain rate and temperature dependent and can be described reasonably well at high strain rates and room temperature by Johnson-Cook model except at very low strains. This might be due to the fact that the strain rate is not strictly constant in the early stage of deformation.

  15. Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tang Hui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Yu Dezhen [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Luo Yan [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Wang Fuping, E-mail: hitth001@yahoo.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. Black-Right-Pointing-Pointer The corrosion resistance of the magnesium alloy has been enhanced by micro-arc oxidation and solution treatment. Black-Right-Pointing-Pointer The coating fabricated by micro-arc oxidation and solution treatment exhibits a high ability to form apatite. - Abstract: Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

  16. Native Oxide Films on AZ31 and AZ61 Commercial Magnesium Alloys ─ Corrosion Behaviour, Effect on Isothermal Oxidation and Sol─gel Thin Film Formation

    OpenAIRE

    Feliu, Sebastían; Barranco, V.; Llorente, Irene; García-Galván, Federico R.; Jimenez Morales, Antonia; Galván Sierra, Juan Carlos; El Hadad, Amir

    2015-01-01

    The authors present a review of their recent research work in an endeavour to interpret the influence of native oxide films on the corrosion behaviour of commercial AZ31 and AZ61 magnesium alloys or on the oxidation kinetics in air at 200°C. The tendency of some of these thin films to be sufficiently protective in mild or weak corrosive environments is examined. For obtaining oxide films with different protective properties, some of the specimens are tested with the surface in the as-received...

  17. Fatigue and Tensile Behavior of Cast, Hot-Rolled, and Severely Plastically Deformed AZ31 Magnesium Alloy

    Czech Academy of Sciences Publication Activity Database

    Zúberová, Z.; Kunz, Ludvík; Lamark, T. T.; Estrin, Y.; Janeček, M.

    2007-01-01

    Roč. 38, č. 9 (2007), s. 1934-1940. ISSN 1073-5623. [UFG-2006. Cloister Irsee, 25.09.2006-27.09.2006] R&D Projects: GA MŠk(CZ) 1P05ME804 Institutional research plan: CEZ:AV0Z20410507 Keywords : AZ31 * Fatigue * ECAP * squeeze casting * hot rolling Subject RIV: JG - Metallurgy Impact factor: 1.278, year: 2007

  18. Slow strain rate stress corrosion cracking behaviour of as-welded and plasma electrolytic oxidation treated AZ31HP magnesium alloy autogenous laser beam weldment

    International Nuclear Information System (INIS)

    The joining of a thin section AZ31HP magnesium alloy was accomplished by laser beam welding in the autogenous mode using a Nd-YAG laser system. Micro hardness evaluation and slow strain rate tensile (SSRT) tests in air revealed that the weld metal had near-matching mechanical properties corresponding to that of the parent alloy. However, in terms of stress corrosion cracking (SCC) resistance as assessed by SSRT tests in ASTM D1384 solution, the weldment was found to have higher susceptibility compared to the parent alloy. The fracture in the weld metal/fusion boundary/HAZ interface suggested that the failure was due to the grain coarsening at the very narrow heat affected zone. The resistance to SCC of the parent alloy and the weldment specimens was found to improve slightly by the application of plasma electrolytic oxidation (PEO) coating from a silicate based electrolyte.

  19. Tensile properties and strain-hardening behavior of double-sided arc welded and friction stir welded AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Microstructures, tensile properties and work hardening behavior of double-sided arc welded (DSAWed) and friction stir welded (FSWed) AZ31B-H24 magnesium alloy sheet were studied at different strain rates. While the yield strength was higher, both the ultimate tensile strength and ductility were lower in the FSWed samples than in the DSAWed samples due to welding defects present at the bottom surface in the FSWed samples. Strain-hardening exponents were evaluated using the Hollomon relationship, the Ludwik equation and a modified equation. After welding, the strain-hardening exponents were nearly twice that of the base metal. The DSAWed samples exhibited stronger strain-hardening capacity due to the larger grain size coupled with the divorced eutectic structure containing β-Mg17Al12 particles in the fusion zone, compared to the FSWed samples and base metal. Kocks-Mecking type plots were used to show strain-hardening stages. Stage III hardening occurred after yielding in both the base metal and the welded samples. At lower strains a higher strain-hardening rate was observed in the base metal, but it decreased rapidly with increasing net flow stress. At higher strains the strain-hardening rate of the welded samples became higher, because the recrystallized grains in the FSWed and the larger re-solidified grains coupled with β particles in the DSAWed provided more space to accommodate dislocation multiplication during plastic deformation. The strain-rate sensitivity evaluated via Lindholm's approach was observed to be higher in the base metal than in the welded samples.

  20. Microstructure stability of ultra-fine grained magnesium alloy AZ31 processed by extrusion and equal-channel angular pressing (EX–ECAP)

    Energy Technology Data Exchange (ETDEWEB)

    Stráská, Jitka, E-mail: straska.jitka@gmail.com [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Janeček, Miloš, E-mail: janecek@met.mff.cuni.cz [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Čížek, Jakub, E-mail: jcizek@mbox.troja.mff.cuni.cz [Department of Low Temperature Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holešovičkách 2, 180 00 Praha 8 (Czech Republic); Stráský, Josef, E-mail: josef.strasky@gmail.com [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Hadzima, Branislav, E-mail: branislav.hadzima@fstroj.uniza.sk [University of Žilina, Research Centre, Univerzitná 1, 010 26 Žilina (Slovakia); Department of Materials Engineering, Faculty of Mechanical Engineering, University of Žilina, Univerzitná 1, 010 26 Žilina (Slovakia)

    2014-08-15

    Thermal stability of the ultra-fine grained (UFG) microstructure of magnesium AZ31 alloy was investigated. UFG microstructure was achieved by a combined two-step severe plastic deformation process: the extrusion (EX) and subsequent equal-channel angular pressing (ECAP). This combined process leads to refined microstructure and enhanced microhardness. Specimens with UFG microstructure were annealed isochronally at temperatures 150–500 °C for 1 h. The evolution of microstructure, mechanical properties and dislocation density was studied by electron backscatter diffraction (EBSD), microhardness measurements and positron annihilation spectroscopy (PAS). The coarsening of the fine-grained structure at higher temperatures was accompanied by a gradual decrease of the microhardness and decrease of dislocation density. Mechanism of grain growth was studied by general equation for grain growth and Arrhenius equation. Activation energies for grain growth were calculated to be 115, 33 and 164 kJ/mol in temperature ranges of 170–210 °C, 210–400 °C and 400–500 °C (443–483 K, 483–673 K and 673–773 K), respectively. - Highlights: • Microhardness of UFG AZ31 alloy decreases with increasing annealing temperature. • This fact has two reasons: dislocation annihilations and/or grain growth. • The activation energies for grain growth were calculated for all temperature ranges.

  1. Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

    DEFF Research Database (Denmark)

    Oddershede, Jette; Camin, Bettina; Schmidt, Søren;

    2012-01-01

    The stress field around a notch in a coarse grained Mg AZ31 sample has been measured under tensile load using the individual grains as probes in an in situ high energy synchrotron diffraction experiment. The experimental set-up, a variant of three-dimensional X-ray diffraction microscopy, allows...... the position, orientation and full stress tensor of each illuminated grain to be determined and, hence, enables the study of evolving stress fields in coarse grained materials with a spatial resolution equal to the grain size. Grain resolved information like this is vital for understanding what...... happens when the traditional continuum mechanics approach breaks down and fracture is governed by local heterogeneities (e.g. phase or stress differences) between grains. As a first approximation the results obtained were averaged through the thickness of the sample and compared with an elastic...

  2. Study on the interface of PVDF coatings and HF-treated AZ31 magnesium alloy: Determination of interfacial interactions and reactions with self-healing properties

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, Thiago F. da, E-mail: thiago.conceicao@hzg.d [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Scharnagl, N. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Center for Biomaterial Development and Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht GmbH, Institute of Polymer Research, Campus Teltow Centre for Biomaterial Development, Kantstrasse 55, 14513 Teltow (Germany); Dietzel, W.; Hoeche, D.; Kainer, K.U. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany)

    2011-02-15

    Research highlights: {yields} Reports a high protection system for the alloy in corrosive environment. {yields} Describes an interfacial process with self-healing properties. {yields} Reports the influence of substrate pre-treatment in the coating performance. - Abstract: In this paper the interface of poly(vinylidene fluoride) coatings prepared by the dip coating method and HF-treated AZ31 magnesium alloy was evaluated. The best performance of this system in corrosion tests compared to ground, as-received and acetic acid cleaned substrates is related to an acid-base interaction at the interface and to interfacial reactions which resulted in a self-healing process. The protectiveness of the samples was investigated using impedance and immersion tests while the coating morphology and interface stability were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy and adhesion tests.

  3. Study on the interface of PVDF coatings and HF-treated AZ31 magnesium alloy: Determination of interfacial interactions and reactions with self-healing properties

    International Nuclear Information System (INIS)

    Research highlights: → Reports a high protection system for the alloy in corrosive environment. → Describes an interfacial process with self-healing properties. → Reports the influence of substrate pre-treatment in the coating performance. - Abstract: In this paper the interface of poly(vinylidene fluoride) coatings prepared by the dip coating method and HF-treated AZ31 magnesium alloy was evaluated. The best performance of this system in corrosion tests compared to ground, as-received and acetic acid cleaned substrates is related to an acid-base interaction at the interface and to interfacial reactions which resulted in a self-healing process. The protectiveness of the samples was investigated using impedance and immersion tests while the coating morphology and interface stability were investigated by scanning electron microscopy, X-ray photoelectron spectroscopy and adhesion tests.

  4. Microstructures and properties of aluminum film and its effect on corrosion resistance of AZ31B substrate

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aluminum films with thickness of 8.78-20.82 μm were deposited on the AZ31B magnesium alloys by DC magnetron sputtering.The influences of aluminum film on the micro-mechanical properties and corrosion behavior Of the magnesium alloys were investigated.The morphology of aluminam film was examined by seanning electron microscopy and the microstructure of aluminum film was analyzed by X-ray diffractometry.Nanoindentation and nanoscratch tests were conducted to investigate their micromechanical properties.Moreover,potentiodynamical polarization test performed in 3.5%NaCl solution was carried out to study their anticorrosion performances.The results show that the surface hardness of AZ31B magnesium alloy with aluminum film is 1.38-2.01GPa.higher than that of the magnesium alloy substrate.The critical load Of Al film/AZ31B substrate is in the range of 0.68-2.77 N.The corrosion current density of AZ31B with aluminum film is 2-3 orders of magnitude less than that of bare AZ31B.And the corrosion potential with aluminum film positively siftfls.Thus aluminum film can increase the corrosion resistance of Mg alloys obviously.

  5. Twinning, dynamic recovery and recrystallization in the hot rolling process of twin-roll cast AZ31B alloy

    International Nuclear Information System (INIS)

    Highlights: → Two different types of twinning, {101-bar 2} and {101-bar 1}, occurred in the rolling process, and {101-bar 1} twins tended to be preferred sites for recrystallization. → DRV and discontinuous recrystallization dominated at moderate strain in the rolling process. → Non-basal slip was homogeneously activated at even larger strains and continuous DRX readily took place on the basis of cellular structures. - Abstract: Hot-rolling experiments with a reduction from 10% to 60% in single pass were conducted on AZ31B twin-roll cast sheets. Optical microscope (OM), electron backscattered diffraction (EBSD) tests and transmission electron microscope (TEM) were used to investigate twinning and DRV/DRX behaviors at different stage in the hot-rolling process. Two types of twinning occurred in the initial stage of hot-rolling process. DRV and discontinuous recrystallization dominated at moderate strain while continuous DRX took place homogeneously throughout original grains at the largest strains.

  6. 植酸浓度对AZ31B镁合金植酸转化膜防腐性能的影响%Influence of Phytic Acid Concentration on Corrosion Resistance of Phytic Acid Conversion Coating on AZ31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    高焕方; 张胜涛; 赵波; 刘益风; 邹勇

    2011-01-01

    在不同浓度的植酸溶液中制备了AZ31B镁合金植酸转化试样,并应用析氢实验及Tafel极化曲线测试其防腐性能,使用SEM,EDS,FTIR观察转化膜形貌、元素组成及官能团构成.结果表明:植酸溶液的浓度对植酸转化试样的防腐性能具有较大的影响,C=4.0g·L-1时所制备的转化试样具有最佳的防腐性能,电流密度较未处理试样降低了2个数量级.此外,植酸转化膜主要由Mg,Al,Zn,O,P等元素组成,并含有PO34-,HPO24-,OH-基团,转化膜存在一定的裂纹,且裂纹处仍有很薄的一层植酸转化膜.%The phytic acid conversion coatings on AZ31B magnesium alloy were formed in different phytic acid concentrations and the corrosion resistance of the conversion samples was studied by hydrogen evolution method and Tafel. The morphology, composition and functional groups were investigated by SEM, EDS and FTIR, respectively. The results indicate that the concentration of phytic acid has obvious influence on the corrosion resistance of the conversion samples, the conversion sample formed under C=4.0g · L-1 has the best corrosion resistance, the current density decreases about two orders than that of the untreated sample. The main elements of the coating are Mg, Al, Zn, O and P, the functional groups are PO43- , HPO42- and OH- . The conversion coating also has few cracks, and the thin coating is formed on the crack.

  7. Corrosion behaviors and effects of corrosion products of plasma electrolytic oxidation coated AZ31 magnesium alloy under the salt spray corrosion test

    Science.gov (United States)

    Wang, Yan; Huang, Zhiquan; Yan, Qin; Liu, Chen; Liu, Peng; Zhang, Yi; Guo, Changhong; Jiang, Guirong; Shen, Dejiu

    2016-08-01

    The effects of corrosion products on corrosion behaviors of AZ31 magnesium alloy with a plasma electrolytic oxidation (PEO) coating were investigated under the salt spray corrosion test (SSCT). The surface morphology, cross-sectional microstructure, chemical and phase compositions of the PEO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction analysis (XRD), respectively. Further, the corrosion process of the samples under the SSCT was examined in a non-aqueous electrolyte (methanol) using electrochemical impedance spectroscopy (EIS) coupled with equivalent circuit. The results show that the inner layer of the coating was destroyed firstly and the corrosion products have significant effects on the corrosion behaviors of the coating. The results above are discussed and an electrochemical corrosion model is proposed in the paper.

  8. Microstructural characterization and mechanical properties of dissimilar friction welding of 1060 aluminum to AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zhida; Qin, Guoliang, E-mail: glqin@sdu.edu.cn; Wang, Liyuan; Meng, Xiangmeng; Li, Fei

    2015-10-01

    Dissimilar welding of aluminum bars and magnesium bars was produced by the friction welding technique. The interfacial microstructure characteristics was evaluated after friction welding of Al–Mg alloy using optical microscopy, scanning electron microscopy, as well as X-ray diffraction analysis. Friction and forge pressure were selected as variable parameters. The friction time was maintained at 10 s for a rotational speed of 2800 rpm. The chemical compositions of the interfaces of the welded joints were determined by using energy dispersive spectroscopy. Experimental results showed that intermetallic compounds (IMCs), consisting of phase β-Al{sub 3}Mg{sub 2} and γ-Al{sub 12}Mg{sub 17}, were generated in the interfaces of the Al and Mg alloys. When the friction and forge pressure increased the thickness of IMCs layer at the interfaces decreased as a result of more mass discarded from the welding interfaces. Heavy thickness of IMCs layer seriously deteriorated the mechanical properties of the joints. Microcracks were generated along the welded interfaces of all the welded samples. Formation of microcracks could be controlled effectively under the higher friction and forge pressure. Mechanical evaluations were conducted by determining microhardness and the tensile tests. It was observed that the tensile strength of the joints depended on the friction and forge pressure and the maximum tensile strength was 138 MPa.

  9. Microstructural characterization and mechanical properties of dissimilar friction welding of 1060 aluminum to AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Dissimilar welding of aluminum bars and magnesium bars was produced by the friction welding technique. The interfacial microstructure characteristics was evaluated after friction welding of Al–Mg alloy using optical microscopy, scanning electron microscopy, as well as X-ray diffraction analysis. Friction and forge pressure were selected as variable parameters. The friction time was maintained at 10 s for a rotational speed of 2800 rpm. The chemical compositions of the interfaces of the welded joints were determined by using energy dispersive spectroscopy. Experimental results showed that intermetallic compounds (IMCs), consisting of phase β-Al3Mg2 and γ-Al12Mg17, were generated in the interfaces of the Al and Mg alloys. When the friction and forge pressure increased the thickness of IMCs layer at the interfaces decreased as a result of more mass discarded from the welding interfaces. Heavy thickness of IMCs layer seriously deteriorated the mechanical properties of the joints. Microcracks were generated along the welded interfaces of all the welded samples. Formation of microcracks could be controlled effectively under the higher friction and forge pressure. Mechanical evaluations were conducted by determining microhardness and the tensile tests. It was observed that the tensile strength of the joints depended on the friction and forge pressure and the maximum tensile strength was 138 MPa

  10. Reversible motion of twin boundaries in AZ31 alloy and new design of magnesium alloys as smart materials

    Czech Academy of Sciences Publication Activity Database

    Molnár, Peter; Ostapovets, Andriy; Jäger, Aleš

    2014-01-01

    Roč. 56, APR (2014), s. 509-516. ISSN 0261-3069 R&D Projects: GA ČR GBP108/12/G043; GA MŠk(CZ) LM2011026; GA ČR GPP108/12/P054 Institutional support: RVO:68378271 Keywords : magnesium alloy * twinning * texture * smart material Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.501, year: 2014

  11. Corrosion Resistance of the Superhydrophobic Mg(OH2/Mg-Al Layered Double Hydroxide Coatings on Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Fen Zhang

    2016-04-01

    Full Text Available Coatings of the Mg(OH2/Mg-Al layered double hydroxide (LDH composite were formed by a combined co-precipitation method and hydrothermal process on the AZ31 alloy substrate in alkaline condition. Subsequently, a superhydrophobic surface was successfully constructed to modify the composite coatings on the AZ31 alloy substrate using stearic acid. The characteristics of the composite coatings were investigated by means of X-ray diffractometer (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, scanning electronic microscope (SEM and contact angle (CA. The corrosion resistance of the coatings was assessed by potentiodynamic polarization, the electrochemical impedance spectrum (EIS, the test of hydrogen evolution and the immersion test. The results showed that the superhydrophobic coatings considerably improved the corrosion resistant performance of the LDH coatings on the AZ31 alloy substrate.

  12. Strain-Controlled Low-Cycle Fatigue Behavior of Friction Stir-Welded AZ31 Magnesium Alloy

    Science.gov (United States)

    Yang, J.; Ni, D. R.; Wang, D.; Xiao, B. L.; Ma, Z. Y.

    2014-04-01

    Strain-controlled low-cycle fatigue (LCF) behavior of friction stir-welded (FSW) AZ31 joints, produced at rotation rates of 800 and 3500 rpm, was studied. The joints exhibited symmetric hysteresis loops, whereas asymmetric loops were observed for the parent material (PM). The fatigue resistance of the FSW joints was slightly improved as the rotation rate increased, and both the FSW joints possessed a fatigue life similar to that of the PM at the low strain amplitude of 0.1 pct. The obtained fatigue data for the PM and FSW joints can be well described using the Coffin-Manson and Basquin's relationships. For the FSW joints, during LCF deformation, the twinning originated from the nugget zone (NZ)/thermomechanically affected zone (TMAZ) boundary and then propagated to the NZ interior. This was attributed to different textures in these regions: the center of the NZ exhibited a hard orientation, whereas a soft orientation was observed in the region around the NZ/TMAZ boundary. The fatigue cracks initiated at the bottom of the joints and propagated along the NZ/TMAZ boundary or the NZ adjacent to the NZ/TMAZ boundary.

  13. The combined effect of static recrystallization and twinning on texture in magnesium alloys AM30 and AZ31

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Etienne; Jiang, Lan; Jonas, John J. [McGill Univ., Montreal, Quebec (Canada). Dept. of Materials Engineering; Godet, Stephane [Univ. Libre de Bruxelles (Belgium). Service Matieres et Materiaux

    2009-04-15

    The potential for decreasing the texture intensity generated during the bulk deformation of Mg alloys was investigated using a combination of contraction twinning, double (secondary) twinning and static recrystallization. A large number of twins was induced by tensile deformation at room temperature. Their volume fraction and the variants selected during straining were found to be largely responsible for the changes evident in the deformation texture. Recrystallization of the twins generated a fine-grained microstructure, although no growth into the matrix grains was observed. In this way, annealing of the deformed samples did not lead to significant further texture changes. (orig.)

  14. The effects of texture and extension twinning on the low-cycle fatigue behavior of a rolled magnesium alloy, AZ31B

    International Nuclear Information System (INIS)

    Research highlights: → Due to in-plane texture symmetry, in-plane loadings show similar LCF resistances. → The through-thickness loading has a worse LCF resistance than in-plane loadings. → The resistance difference is attributed to different twinning-detwinning sequences. → The different activation sequences lead to inverted hysteresis loop shapes. - Abstract: The effect of texture on the low-cycle fatigue behavior of a rolled magnesium alloy, AZ31B, was studied at room temperature. It is shown that the Coffin-Manson and Basquin relationships can be used to describe the fatigue resistance of the alloy. The alloy loaded along the rolling direction exhibits only slightly better low-cycle fatigue resistance than that loaded along the transverse direction, due to the in-plane texture symmetry. The in-plane cases exhibit better fatigue behavior than the through-thickness loading. Neutron diffraction and synchrotron diffraction were employed to assist in making mechanistic understandings for the findings. The fundamental difference in the low-cycle fatigue behaviors between the in-plane and through-thickness loadings is attributed to the different activation sequences of twinning and detwinning mechanisms involved and, particularly, the greater requirement for c-axis compression of the grains during the through-thickness tests. The different activation sequences are essentially determined by the initial crystallographic texture, such that the inverted hysteresis-loop shapes are observed.

  15. Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

    Science.gov (United States)

    Tang, Hui; Yu, Dezhen; Luo, Yan; Wang, Fuping

    2013-01-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

  16. Simulation of stress concentration in Mg alloys using the crystal plasticity finite element method

    International Nuclear Information System (INIS)

    A crystal plasticity finite element method (CPFEM), considering both crystallographic slip and deformation twinning, was developed to simulate the spatial stress concentration in AZ31 Mg alloys during in-plane compression. A predominant twin reorientation (PTR) model was successfully implemented to capture grain reorientation due to deformation twinning in twin-dominated deformation. By using the direct mapping technique for electron backscatter diffraction (EBSD) data, CPFEM can capture the heterogeneity of stress concentration at the grain boundaries in AZ31 Mg alloys during in-plane compression. The model demonstrated that deformation twinning enhances the local stress concentration at the grain boundaries between untwinned and twinned grains.

  17. The corrosion properties of phosphate coating on AZ31 magnesium alloy: The effect of sodium dodecyl sulfate (SDS) as an eco-friendly accelerating agent

    International Nuclear Information System (INIS)

    Sodium nitrite has been used as an accelerating agent in phosphating bath to improve its properties. However, it is well known that sodium nitrite is a carcinogenic component in phosphating sludge. In this study, it has been aimed to replace sodium nitrite by an environmentally friendly accelerating agent. To this end, sodium dodecyl sulfate (SDS) was used in phosphating bath to improve the phosphate coating formation on an AZ31 magnesium alloy. The effect of SDS/sodium nitrite ratio on the phosphated samples properties was also studied. Using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), direct current (DC) polarization and electrochemical impedance spectroscopy (EIS) the properties of phosphated magnesium samples were studied. Results showed uniform phosphate coating formation on the magnesium sample mostly in hopeite phase composition. In addition, a denser and less permeable coating can be obtained at these conditions. The corrosion resistance of the phosphated samples was superiorly improved using higher SDS concentration in the phosphating bath.

  18. Effect of deformation conditions on twinning of AZ31 magnesium alloy during compression test%变形条件对AZ31镁合金冷压缩过程中孪生的影响

    Institute of Scientific and Technical Information of China (English)

    刘天模; 袁晗琦; 彭天成; 刘建忠

    2010-01-01

    在新三思拉伸试验机CMT-5150上对均匀态AZ31镁合金进行室温压缩试验,研究了在变形量分别为5%、7.5%、10%、12.5%、15%以及变形速率分别为0.5、1、2、4 mm/min时压缩变形组织中孪晶的形态与分布.结果表明:在压缩变形初期,只有少量晶粒内出现孪晶,孪晶较宽;而在压缩变形末期,孪晶几乎分布于所有晶粒中,且出现了细而长的孪晶.孪晶分数随变形程度的增大而上升.随着变形速率的增大,孪晶形态变细,且其密度增大,试样的屈服强度和抗压强度都升高.

  19. Influence of texture on dynamic recrystallization and deformation mechanisms in rolled or ECAPed AZ31 magnesium alloy

    OpenAIRE

    Valle, Jorge del; Ruano, Oscar Antonio

    2008-01-01

    Equal channel angular pressing (ECAP) and hot rolling are widely used processing routes in magnesium alloys. These routes induce different textures that affect their mechanical properties. In the presentwork, the influence of the texture on dynamic recrystallization (DRX) and deformation mechanisms was investigated. During tensile deformation at moderate temperatures, a stronger enhancement of DRX in rolled samples than in ECAPed samples is observed. Simultaneously, in both samples, ...

  20. Effect of Electrolyte Temperature on Microstructure and Corrosion Resistance of Micro - Arc Oxidation Coatings of Magnesium Alloy%AZ31B镁合金微弧氧化电解液温度对膜组织与性能的影响

    Institute of Scientific and Technical Information of China (English)

    翟彦博; 陈红兵; 马秀腾

    2013-01-01

    on the bath potential for micro-arc oxidation of AZ31B Mg alloy as well as the growth rate, microhardness, corrosion resistance and microstructure of as-obtained micro-arc oxidation coatings was investigated. It was found that elevating electrolyte temperature favored to accelerated growth of the micro-arc oxidation coatings on Mg alloy but led to enlarged discharge channel and reduced compactness of the coatings, thereby resulting in reduced microhardness and corrosion resistance of the micro-arc oxidation coatings.%电解液温度是影响镁合金微孤氧化膜形成及质量的关键因素之一,过去对此鲜有系统研究.为此,对比研究了20,40,60℃3种电解液温度对AZ31B镁合金微弧氧化膜的生长速度、槽压、显微硬度、耐蚀性和微观组织的影响.结果显示,较高的电解液温度可以提高氧化膜的生长速度,但会导致膜层中的放电通道增大,使其致密性变差,从而降低了膜层的显微硬度与耐蚀性.

  1. Mesoscale Modeling and Validation of Texture Evolution during Asymmetric Rooling and Static Recrystallization of Magnesium Alloy AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Radhakrishnan, Balasubramaniam [ORNL; Gorti, Sarma B [ORNL; Stoica, Grigoreta M [ORNL; Muralidharan, Govindarajan [ORNL; Stoica, Alexandru Dan [ORNL; Wang, Xun-Li [ORNL; Specht, Eliot D [ORNL; Kenik, Edward A [ORNL; Muth, Thomas R [ORNL

    2012-01-01

    The focus of the present research is to develop an integrated deformation and recrystallization model for magnesium alloys at the microstructural length scale. It is known that in magnesium alloys nucleation of recrystallized grains occurs at various microstructural inhomogeneities such as twins and localized deformation bands. However, there is a need to develop models that can predict the evolution of the grain structure and texture developed during recrystallization and grain growth, especially when the deformation process follows a complicated deformation path such as in asymmetric rolling. The deformation model is based on a crystal plasticity approach implemented at the length scale of the microstructure that includes deformation mechanisms based on dislocation slip and twinning. The recrystallization simulation is based on a Monte Carlo technique that operates on the output of the deformation simulations. The nucleation criterion during recrystallization is based on the local stored energy and the Monte Carlo technique is used to simulate the growth of the nuclei due to local stored energy differences and curvature. The model predictions are compared with experimental data obtained through electron backscatter analysis and neutron diffraction.

  2. Influence of annealing on the microstructure of commercial Mg alloy AZ31 after mechanical forming

    Czech Academy of Sciences Publication Activity Database

    Jäger, A.; Lukáč, P.; Gärtnerová, Viera; Haloda, J.; Dopita, M.

    2006-01-01

    Roč. 432, 1-2 (2006), 20-25. ISSN 0921-5093 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnesium * texture * static recrystallization * grain boundaries * twinning * electron backscatter diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.490, year: 2006

  3. Analysis of the Deformability of Two-Layer Materials AZ31/Eutectic / Analiza Możliwości Odkształcania Plastycznego Materiału Dwuwarstwowego AZ31/Eutektyka

    Directory of Open Access Journals (Sweden)

    Mola R.

    2015-12-01

    Full Text Available The paper present the results of physical simulation of the deformation of the two-layered AZ31/eutectic material using the Gleeble 3800 metallurgical processes simulator. The eutectic layer was produced on the AZ31 substrate using thermochemical treatment. The specimens of AZ31 alloy were heat treated in contact with aluminium powder at 445°C in a vacuum furnace. Depending on the heating time, Al-enriched surface layers with a thickness of 400, 700 and 1100 μm were fabricated on a substrate which was characterized by an eutectic structure composed of the Mg17Al12 phase and a solid solution of aluminium in magnesium. In the study, physical simulation of the fabricated two-layered specimens with a varying thickness of the eutectic layer were deformed using the plane strain compression test at various values of strain rates. The testing results have revealed that it is possible to deform the two-layered AZ31/eutectic material at low strain rates and small deformation values.

  4. Interfacial Microstructure and Mechanical Properties of Al Alloy/Mg Alloy Laminated Composite Plates Fabricated by Equal Channel Angular Processing

    Institute of Scientific and Technical Information of China (English)

    LI Guorui; ZHAO Dong; ZHAO Yaojiang; ZHOU Bin; WANG Hongxia

    2016-01-01

    KAl (7075) alloy /Mg (AZ31) alloy laminated composite plates were successfully fabricated by the equal channel angular processing (ECAP) by using route A for 1, 2, and 3 passes at 573 K, respectively. After fabrication, the 1-pass ECAPed laminated composite plates were annealed at different temperatures. The microstructure evolution, phase constituent, and bonding strength near the joining interface of Al (7075) alloy /Mg (AZ31) alloy laminated composites plates were evaluated with scanning electron microscopy, X-ray diffraction, and shear tests. The experimental results indicated that a 20 μm diffusion layer was observed at the joining interface of Al (7075) alloy /Mg (AZ31) alloy laminated composites plates fabricated by the 1-pass ECAP, which mainly included Al3Mg2 and Mg17Al12 phases. With the increase of passes, the increase of diffusion layer thickness was not obvious and the form of crack in these processes led to the decrease of bonding strength. For 1-pass ECAPed composites, the thickness of diffusion layer remained unchanged after annealed at 473 K, while the bonding strength reached its maximum value 29.12 MPa. However, after elevating heat treatment temperature to 573 K, the thickness of diffusion layer increased rapidly, and thus the bonding strength decreased.

  5. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    OpenAIRE

    Escudero, M. L.; Clemente, C; Rubio, J C; Alobera, M. A.; García-Alonso, M. C.; del Valle, J. A.; C. Iglesias; Pérez-Maceda, B. T.; Carboneras, M.; Lozano, R.M.

    2011-01-01

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, a...

  6. Comportamiento de la corrosión de aleaciones de magnesio AZ31-B en ambiente marino, modificadas por el proceso de fricción-agitación Corrosion behavior in marine environment of magnesium alloy AZ31-B welded by friction-agitation process

    Directory of Open Access Journals (Sweden)

    Willian Aperador Chaparro

    2012-04-01

    Full Text Available En el presente artículo se estudia el comportamiento de la corrosión de la aleación de magnesio AZ31-B en ambiente marino simulado, modificada mediante el proceso de fricción-agitación (PFA, con el fin de determinar el efecto de las variables del proceso, velocidad de rotación y velocidad de avance. Se llevaron a cabo análisis mediante espectroscopia de impedancia electroquímica y curvas de polarización potencio-dinámicas (Tafel. Adicionalmente, se determinó la microestructura en las zonas del cordón de soldadura a través de metalografía óptica. Finalmente, se analizaron los productos de corrosión formados en la superficie de las muestras por medio del microscopio electrónico de barrido (SEM equipado con el analizador químico por EDS. Se observó que una relación de velocidad de avance/velocidad de rotación mayor produce menor velocidad de corrosión y con ello mayor resistencia a la corrosión en medios salinos, al parecer relacionados con el gran tamaño de grano en la zona agitada, que corresponde a más entrada de calor.The corrosion behavior of AZ31B magnesium alloy modified by friction stir processing (FSP was studied in simulated marine environment, in order to determine the effect of process variables rotation speed and travel speed. The corrosion analysis was carried upon by means of electrochemical impedance spectroscopy and potentiodynamic polarization curves (Tafel, metallographic analysis of the welded zones was done by optical microscopy and the chemical analysis of the corrosion products were done by using scanning electron microscope (SEM, equipped with EDS analyzer. It was observed that the increase of the rate rotation speed/travel speed of the process produces a decrease in the corrosion rate and the corresponding increase of the corrosion resistance in marine environment, apparently related to the higher grain size found in the stir zone, corresponding to a higher heat input.

  7. Synthesis of Mg2Si for thermoelectric applications using magnesium alloy and spark plasma sintering

    International Nuclear Information System (INIS)

    Highlights: • Magnesium alloy AZ31 was selected to fabricate Al-doped n-type thermoelectric Mg2Si. • No grinding and ball milling were employed. • The crystalline grains in the Mg2Si bulk were identical to the raw Si powder in size. • The thermoelectric figure of merit (ZT) was 0.58 at 844 K in Al-doped Mg2Si. -- Abstract: Magnesium silicide was synthesized through a solid-state reaction at 400 °C between chips of commercially pure Mg or AZ31 magnesium alloy and silicon fine powders. The use of alloy AZ31 allows Al to be introduced as a dopant. The synthesized silicide powders were consolidated by spark plasma sintering at 750 °C. X-ray diffraction and scanning electron microscopy were used to confirm the phase purity and structural evolution from powder to bulk material. The crystalline grains in the Mg2Si bulk were identical to the raw Si powder in size. The Al impurity increased the electrical conductivity of Mg2Si while the Seebeck coefficient was lowered. The thermal conductivities were almost the same for Mg2Si and doped Mg2Si. The optimal thermoelectric figure of merit (ZT) was 0.58 at 844 K in the n-type Al-doped Mg2Si material. Inductively coupled plasma emission spectroscopy was employed to determine the concentration of Al dopant

  8. Quick Surface Treatment of AZ31B by AC Micro-arc Oxidation

    Institute of Scientific and Technical Information of China (English)

    WANG Shenglin; ZHANG Peng; DU Yunhui; WANG Yujie; HAO Zhiqiang

    2014-01-01

    In order to explore an effective way to shorten treatment time and enhance the quality of treatment coating, AC micro-arc oxidation was conducted to treat the surface of AZ31B deformation magnesium alloy in KF+KOH treatment solution. The influences of micro-arc oxidation parameters such as concentration of KF, concentration of KOH, output voltage of booster, temperature of treatment solution, and treatment time on treatment coating thickness were raveled out under different conditions. The structure and composition of treatment coating were determined, the growth mechanism of treatment coating was discussed, and the quick surface treatment technology for compact treatment coating with maximum thickness was developed. The experimental results show that:A maximum 33μm-thick compact treatment coating, consisting of MgF2 and MgO mainly, can be formed on AZ31B in 112s under the conditions of 1 132 g/L KF, 382 g/L KOH, 66 V for output voltage of booster and 34℃of treatment solution which were optimized by a genetic algorithm from the model established by artificial neural networks. There are no“crater-shaped”pores in this treatment coating as the heat shock resulting from the smooth variation of AC sinusoidal voltage is far smaller than that of the rigidly varied DC or pulse current. The treatment time is only one sixth of that adopted in the other surface treatment technology at best, principally for the reason that the coating can always grow irrespective of the electric potential of AZ31B. This investigation lays a firm foundation for the extensive application of magnesium alloy.

  9. Constitutive model of AZ31B sheet at various pre-strains and temperatures

    Science.gov (United States)

    Kim, Heon Young; Seo, Oh Suk; Lee, Chung An; Kim, Ji Hoon; Nguyen, Ngoc-Trung; Lee, Myoung-Gyu

    2013-12-01

    Due to their high specific strength, vibration absorption capability, and excellent corrosion resistance, Mg alloys have been potential alternative to other lightweight materials in the automotive industry. Mg alloys are known to have unique mechanical properties; i.e., yielding asymmetry, anisotropy, unusual hardening behavior at room temperature. Usually, Mg alloy sheets have inferior formability at room temperature, but the formability increases when the temperature increases. Moreover, the asymmetry and anisotropy become less significant due to the activation of non-basal slip systems at higher temperature. Utilizing this unique properties, the forming of Mg alloy sheets has been frequently conducted at the temperature of 200 °C or higher, at which twinning effect is less dominant. However, the forming process at elevated temperature lowers production speed due to the additional heating and cooling stages. To resolve this problem, studies on technology that maximizes the formability of Mg alloy sheets at lower temperature have been widely conducted. In this paper, the response of AZ31B Mg alloy sheets under tension-compression cyclic loading at different pre-strains and temperatures was measured experimentally. Then a practical hardening model was developed to reproduce the measured stress-strain responses, which can be applied to the simulation of sheet metal forming of Mg alloy sheets.

  10. Improving corrosion resistance of AZ31B magnesium alloy via a conversion coating produced by a protic ammonium-phosphate ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Elsentriecy, Hassan H. [Materials Science and Technology Division, Oak Ridge National Laboratory, TN (United States); Central Metallurgical Research and Development Institute, Cairo (Egypt); Qu, Jun, E-mail: qujn@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, TN (United States); Luo, Huimin [Energy and Transportation Science Division, Oak Ridge National Laboratory, TN (United States); Meyer, Harry M.; Ma, Cheng; Chi, Miaofang [Materials Science and Technology Division, Oak Ridge National Laboratory, TN (United States)

    2014-10-01

    Magnesium alloys are susceptible to corrosion because of their high reactivity and low electrode potential. The present work introduces a conversion coating using a protic ammonium-phosphate ionic liquid (IL). Initial results on the AZ{sub 31}B Mg alloy have demonstrated substantially improved corrosion resistance for the IL treatment at 300 °C (IL{sub 3}00C) compared to the treatment at room temperature. Potentiodynamic polarization analysis of the IL{sub 3}00C treated Mg surface in a NaCl solution exhibited a strong passivation behavior. No pretreatment is needed and the treated surface morphology is well preserved. Cross-sectional nanostructure examination using transmission electron microscopy and element mapping using energy-dispersive X-ray spectroscopy have revealed the IL{sub 3}00C conversion coating to be a 70–80 nm thick with a two-layer structure. Further surface chemical analysis using X-ray photoelectron spectroscopy suggested such an IL conversion coating possibly composed of metal oxides, metal phosphates, and carbonaceous compounds. - Highlights: • Anti-corrosion conversion film for Mg by a protic ammonium-phosphate ionic liquid • No pretreatment needed and no change in surface appearance and morphology • The ionic liquid conversion film of 70–80 nm thick and a two-layer structure.

  11. Parameters optimization for friction spot welding of AZ31 magnesium alloy by Taguchi method Otimização dos parâmetros de soldagem por fricção por ponto da liga de magnésio AZ31 pelo método de Taguchi

    Directory of Open Access Journals (Sweden)

    Leonardo Contri Campanelli

    2012-03-01

    Full Text Available Friction spot welding (FSpW is a solid state welding process suitable for producing spot-like joints, especially in lightweight materials, which are particularly interesting due to the weight saving potential. The plunging of an especially designed non-consumable and rotating tool creates a connection between overlapped sheets through frictional heat and plastic deformation. Minimum material loss is observed, and therefore a fully consolidated joint with flat surface (no keyhole is obtained. In the current study, the effect of FSpW parameters, such as rotational speed, plunge depth and dwell time, on lap shear strength of AZ31 magnesium alloy joints was investigated. The optimization of input process parameters was carried out through Taguchi approach of DOE. Analysis of variance was applied to determine the individual importance of each parameter. Main effect plots were used to indicate the best levels for maximizing lap shear strength. The results show that tool plunge depth has the higher effect on the weld strength, followed by rotational speed and dwell time.A soldagem por fricção por ponto (FSpW é um processo de soldagem no estado sólido adequado para a produção de juntas pontuais, especialmente em materiais leves, que são particularmente interessantes devido ao potencial de redução de peso. A penetração de uma ferramenta não-consumível e rotacional especialmente desenvolvida cria uma junção entre as placas sobrepostas através de calor por fricção e deformação plástica. A perda de material é mínima, obtendo-se, portanto, uma junta totalmente consolidada com superfície plana (sem furo. Neste trabalho, investigou-se o efeito dos parâmetros do FSpW, tais como velocidade de rotação, profundidade de penetração e tempo de residência, na resistência ao cisalhamento das juntas de liga de magnésio AZ31. A otimização dos parâmetros de entrada do processo foi realizada através do método de Taguchi de DOE. A an

  12. Influences of tool shoulder diameter to plate thickness ratio (D/T) on stir zone formation and tensile properties of friction stir welded dissimilar joints of AA6061 aluminum–AZ31B magnesium alloys

    International Nuclear Information System (INIS)

    Highlights: ► Friction stir welding of dissimilar aluminum–magnesium alloys is reported. ► The effect of shoulder diameter to plate thickness on the properties were studied. ► Microstructure, microhardness and tensile properties were evaluated. ► Shoulder diameter to plate thickness ratio of 3.5 yielded superior properties compared to other joints. -- Abstract: Friction stir welding (FSW) is capable of joining dissimilar materials. In FSW, a rotating shoulder with a profiled pin moves between sheets of the pieces to be joined. As the rotating tool travels along the weld line, frictional heat is generated between the base material and tool shoulder. This heat is however lower than in fusion welding methods. In this work the influences of the tool shoulder diameter (one of the heat generation source) on the macrostructure, microstructure and tensile properties of the dissimilar AA6061 Aluminum and AZ31 Magnesium alloys were experimented. From this investigation, it was found that the joints fabricated using a shoulder diameter of 21 mm (3.5 times the plate thickness) exhibited superior tensile properties compared to its counterparts.

  13. Microstructure and Mechanical Properties of AZ31 Magnesium Alloy Produced by Continuous Variable Cross-section Recycled Extrusion%连续变断面循环挤压AZ31镁合金的微观组织与力学性能

    Institute of Scientific and Technical Information of China (English)

    丁茹; 刘长瑞; 王成; 任红霞

    2009-01-01

    采用连续变断面循环挤压技术(CVCE)对AZ31镁合金进行循环挤压.采用光学显微镜、电子拉伸机等设备,分析变形前及不同循环道次后AZ31镁合金的微观组织和力学性能.结果表明:AZ31镁合金经10循环CVCE后,平均晶粒尺寸由变形前25.3μm有效细化到5.5μm;伸长率提高到34.3%,抗拉强度下降到200MPa.由于晶粒细化效应,导致α相主要变形机制由1循环的孪生变为随后道次的位错滑移.抗拉强度的降低与挤压后(0001)晶面取向分布的分散性有关;伸长率的增大与晶粒细化和滑移面的激活有关.

  14. Comportamiento mecánico de la aleación AZ31 reforzada con nanofibras de carbono

    Directory of Open Access Journals (Sweden)

    Adeva, P.

    2010-12-01

    Full Text Available The aim of this study is to investigate the effect of reinforcing AZ31 with carbon nanofibres. The materials AZ31, AZ31-1 % C y AZ31-2 % C were produced by a conventional powder metallurgy route consisting of mechanical mixing of nanofibres and powders of AZ31, cool compactation and extrusion at 350 °C. After extrusion the three materials exhibited a recrystallized microstructure of similar grain size, fine and rather inhomogeneous. Furthermore, they presented a weak fibre texture with basal plane parallel to the extrusion direction. The tensile properties were affected by the nanofibres presence only at 100 °C. At this temperature, yield strength and tensile strength were 30% higher than in the unreinforced alloy.

    En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedades mecánicas de la aleación AZ31 procesada por una ruta pulvimetalúrgica convencional. Se prepararon tres materiales, AZ31, AZ31- 1 % C y AZ31-2 % C. Tras una mezcla mecánica de las nanofibras con los polvos de AZ31, se precompactaron en frío y se extruyeron a 350 °C. Los tres presentan una microestructura recristalizada con un tamaño de grano similar, fino aunque algo heterogéneo. Los tres materiales presentan una débil textura de fibra con el plano basal paralelo a la dirección de extrusión. Las propiedades mecánicas a tracción únicamente se ven afectadas por la presencia de nanofibras a 100 °C superando los materiales reforzados en un 30 % a los valores de límite elástico y resistencia de la aleación sin reforzar.

  15. Properties of the AZ31 Magnesium Alloy Round Bars Obtained in Different Rolling Processes / Własności Prętów Okrągłych Ze Stopu Magnezu AZ31 Otrzymanych W Różnych Procesach Walcowania

    Directory of Open Access Journals (Sweden)

    Stefanik A.

    2015-12-01

    Full Text Available Currently magnesium alloy bars are manufactured mainly in the extrusion process. This method has some drawbacks, which include: low process capacity, considerable energy demand, small length of finished products. Therefore it is purposeful to develop efficient methods for manufacturing of Mg alloy products in the form of bars, such methods include groove rolling and three-high skew rolling processes. Modified stretching passes provide change in material plastic flow, which contributes to the occurrence of the better distribution of stress and strain state than in the case of rolling in classical stretching passes. One of the modern method of Mg alloy bars production is rolling in a three-high skew rolling mill, which allows to set in a single pass a larger deformation compared to the rolling in the stretching passes.

  16. High speed roll casting of Mg alloy strip by a vertical type twin roll caster

    Directory of Open Access Journals (Sweden)

    H. Watari

    2006-02-01

    Full Text Available Purpose: The possibility of high speed roll casting of AZ31, AM60 and AZ91 was investigated. Warm deep drawing of roll cast magnesium alloy was operated. and formability of roll cast magnesium strip was cleared.Design/methodology/approach: A vertical type high speed twin roll caster was used. The roll casting was operated in the air atmosphere. The casting speed was from 60 m/min up to 180 m/min. Low temperature casting was adopted to realize high speed casting.Findings: Strip thinner 3 mm with 100 width could be cast continuously. The casting ability became better with increasing content of Al. Roll cast Mg alloy strips could be hot-rolled down to 0.5 mm. AZ31 as-cast strip could be thinner down to 0.5 mm only by three times of hot rolling. Deep drawing was operated with three kinds of Mg alloy at 250°C, and LDR value was larger than 2.0. It was shown that deep drawing of AZ91 alloy for casting was possible.Research limitations/implications: There was tendency that cracks occurred at the center in the thickness direction as Al content increased.Practical implications: Sheet metal forming of magnesium alloy with high content Al can be realized.Originality/value: It was shown that possibility of high speed roll casting of magnesium alloy, and warm deep drawing of roll cast AZ91 strip.

  17. Examination of dynamic recrystallization during compression of AZ31 magnesium

    Institute of Scientific and Technical Information of China (English)

    XIN RenLong; WANG BingShu; CHEN XingPin; HUANG GuangJie; LIU Qing

    2009-01-01

    This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of mag-nesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300Ⅱ and a strain rate of 0.01 s-1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) bounda-ries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.

  18. Examination of dynamic recrystallization during compression of AZ31 magnesium

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300℃ and a strain rate of 0.01 s-1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) bounda-ries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.

  19. A study of strontium doped calcium phosphate coatings on AZ31

    International Nuclear Information System (INIS)

    Calcium phosphate (CaP) coatings have been studied to tailor the uncontrolled non-uniform corrosion of Mg based alloys while simultaneously enhancing bioactivity. The use of immersion techniques to deposit CaP coatings is attractive due to the ability of the approach to coat complex structures. In the current study, AZ31 substrates were subjected to various pretreatment conditions prior to depositing Sr2+ doped and undoped CaP coatings. It was hypothesized that the bioactivity and corrosion protection of CaP coatings could be improved by doping with Sr2+. Heat treatment to elevated temperatures resulted in the diffusion of alloying elements, Mg and Zn, into the pretreated layer. Sr2+ doped and undoped CaP coatings formed on the pretreated substrates consisted of biphasic mixtures of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA). Electrochemical corrosion experiments indicated that the extent of Sr2+ doping and pretreatment both influenced the corrosion protection. Cytotoxicity was evaluated with MC3T3-E1 mouse preosteoblasts and human mesenchymal stem cells (hMSCs). For both cell types, proliferation decreased upon increasing the Sr2+ concentration. However, both osteogenic gene and protein expression significantly increased upon increasing Sr2+ concentration. These results suggest that Sr2+ doped coatings are capable of promoting osteogenic differentiation on degradable Mg alloys, while also enhancing corrosion protection, in comparison to undoped CaP coatings

  20. Modeling in vivo corrosion of AZ31 as temporary biodegradable implants. Experimental validation in rats

    International Nuclear Information System (INIS)

    In this paper, two complementary approaches, mathematical modeling and experimental results are combined to identify variables that affect the in vivo biodegradation of magnesium implants. The in vivo corrosion behavior of AZ31 alloy proposed for temporary applications as fixation of bone fractures has been modeled solving the Laplace equation by finite element method (FEM). Bar-shaped AZ31 implants of 1 mm diameter and 20 mm length were inserted in Wistar rat femurs with and without a fracture. The presence of gas around AZ31 implants inside the femurs has been detected in situ at the epiphysis and in fractured areas by computerized tomography (CT). Examining some in vivo conditions, the model confirms that magnesium-alloy devices have different biodegradation behavior, depending on the thickness of electrolyte at the implantation site and can be used for predicting the biodegradation behavior. - Highlights: • Modeling of AZ31 corrosion by solving the Laplace by finite element method • Electrolyte thickness is a key factor in the in vivo corrosion of magnesium alloys. • A critical thickness below which corrosion is focused around impurities is identified. • The critical value is less evident in a material with a high number of impurities. • Experimental and numerical results explain the biodegradation of magnesium implants

  1. Tribological Analysis of Mg2Si Particulates Reinforced Powder Metallurgy Magnesium Alloy Composites under Oil Lubrication Condition

    Directory of Open Access Journals (Sweden)

    Katsuyoshi Kondoh

    2009-01-01

    Full Text Available For the evaluation of wear behavior of Mg composites under oil lubrication conditions, powder metallurgy Mg97Y2Zn1 alloy reinforced with additive Mg2Si particles were fabricated by the repeated plastic working (RPW and hot extrusion. The RPW process was effective in refining both Mg2Si reinforcements and α-Mg grains causing the matrix hardening. When increasing the repetition number of RPW process from 200 to 600 cycles, the particle size of Mg2Si additives changed from 8 μm to 1~2 μm, and α-Mg grain size was 1 μm or less. With regard to the defensive and offensive properties of Mg alloys reinforced with Mg2Si dispersoids, the composite had superior adhesive wear resistance compared with the conventional Mg alloys because of its extremely high microhardness of 95~180 Hv by RPW process. The uniform distribution of refined Mg2Si particles was useful for improving both defensive and offensive properties against AZ31B counter disk specimens. The Mg2Si prominent dispersoids in the matrix were also effective in forming the oil grooves around them, and caused the low and stable friction coefficient. On the other hand, in the case of the composite containing coarse Mg2Si particles, severely deep scratches were given on the counter face of the AZ31B disk, and resulted in an unstable and high friction coefficient.

  2. Parameters optimization of the friction stir spot welding for AZ31 magnesium alloy based on Taguchi orthogonal array%基于田口方法的AZ31镁合金搅拌摩擦点焊工艺参数优化

    Institute of Scientific and Technical Information of China (English)

    陈松林; 张大童; 张文; 邱诚

    2015-01-01

    按照正交表对9组AZ31镁合金搭接试样进行搅拌摩擦点焊,采用田口方法对接头的力学性能进行了信噪比和方差分析.结果表明,搅拌摩擦点焊工艺参数对接头最大拉伸载荷影响由大到小依次为旋转速度、停留时间和压下量.在1 000 r/min旋转速度、5s停留时间、4.6 mm下压量条件下,得到的接头具有最大的拉伸力.组织和硬度分析表明,拉伸承载能力最强的试样冶金结合区和拉伸变形量最大,但硬度值最低.拉伸断口形貌分析表明,点焊接头断裂方式均为韧-脆混合型断裂.

  3. Compressive behaviour of SiC/ncsc reinforced Mg composite processed through powder metallurgy route

    International Nuclear Information System (INIS)

    Highlights: • ncsc reinforced Mg composite is developed by powder metallurgy route. • Porosity measurement showed minimal porosity in AZ31B/SiC/ncsc Mg composite. • Compressive properties decreased with increase in weight percentage of ncsc. • Impact strength decreased with increase in weight percentage of ncsc. - Abstract: In this present work nano coconut shell charcoal (ncsc) and silicon carbide (SiC) particulates were reinforced with AZ31B Mg alloy and suitable magnesium composite was developed by using the powder metallurgy technique followed by hot extrusion. Density measurement of the Mg composites revealed that the addition of ncsc significantly improved the density of the composites and porosity measurement showed minimal porosity. The microstructure of the composites showed even distribution of the ncsc in the AZ31B/3SiC Mg composite. The compressive and impact behaviour of the samples were characterized, the results showed that on increasing the weight percentage of ncsc in AZ31B/3SiC/0.5ncsc Mg composites the mechanical properties such as ultimate compressive strength, 0.2% yield strength, ductility and impact strength decreased. The scanning electron microscope (SEM) analysis of fractured surface of AZ31B Mg alloy and AZ31B/3SiC/0.5ncsc Mg composites showed quasi-cleavage fracture. The presence of ncsc above 0.5 wt% composites revealed mixture of quasi cleavage planes and some dimples

  4. Enhanced corrosion resistance of magnesium alloy by a silane-based solution treatment after an in-situ formation of the Mg(OH)2 layer

    Science.gov (United States)

    Gong, Fubao; Shen, Jun; Gao, Runhua; Xie, Xiong; Luo, Xiong

    2016-03-01

    A novel organic-inorganic Mg(OH)2/silane surface layer has been developed for corrosion protection of AZ31 magnesium alloy. The results of electrochemical impedance spectroscopy (EIS), the immersion tests, Fourier-transform infrared spectroscopy (FTIR) and sellotape tests showed that the Mg(OH)2/silane-based composite surface layer possessed excellent corrosion resistance and very good adhesion due to the formation of Si-O-Mg bond between Mg(OH)2 layer and silane layer. Electrochemical impedance spectroscopy tests results indicated that for the long-term corrosion protection of AZ31 the increase of the curing temperature improved the impedance of the composited layer when the curing temperature was lower than 130 °С. However, the impedance of the composited layer deceased when the curing temperature was more than 130 °С due to the carbonization of the silane layer.

  5. Evolution of Microstructure in Rolled Mg-Based Alloy. Textural Aspect / Ewolucja Mikrostruktury W Walcowanym Stopie Na Bazie Mg. Aspekt Teksturowy

    Directory of Open Access Journals (Sweden)

    Drzymała P.

    2015-12-01

    Full Text Available Magnesium alloys are the lightest structural materials, which makes them particularly suitable for use in the aircraft and automotive industry. However, due to hexagonal close-packed crystal structure, resulting in insufficient number of independent slip systems, magnesium alloys exhibit poor formability at room temperature. Conventional methods of work hardening of magnesium alloys requires the temperature about 300°C, which favours simultaneously processes of thermal recovery and grain growth, but decreases beneficial microstructure strengthening effect. Thus, it is a crucial to undertake development of a technology for semi-finished magnesium alloys elements, which will ensure better mechanical properties of the final products by forming desirable microstructure. In the paper we present the development of crystallographic texture of the Mg-based alloy (Mg-AZ31 in the form of pipe extruded at 430°C and subjected to pilger rolling at relatively low temperature.

  6. Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

    Science.gov (United States)

    Anawati, Asoh, Hidetaka; Ono, Sachiko

    2016-04-01

    Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

  7. Texture Evolution and Twinning During the Expansion of Hot Extruded AZ31 + Sr Seamless Tubes

    Science.gov (United States)

    Sadeghi, Alireza; Martin, Étienne; Pekguleryuz, Mihriban

    2014-12-01

    Seamless tubes of AZ31, AZ31 + 0.4, and 0.8 wt pctSr were extruded at elevated temperatures. By compressing pure copper inserts inside the tubes, the extruded tubes were expanded at room and elevated temperatures [373 K and 473 K (100 °C and 200 °C)]. Microstructural examinations reveal the formation of twining in the as-extruded and expanded tubes. The amount of twinning decreased with increasing level of Sr in the expanded microstructures as a result of grain refinement and of decreasing Al in solution that facilitates dislocation motion. During expansion at room temperature, AZ31 shows higher elongation and lower strength than the alloys containing Sr. At 473 K (200 °C), compared to the lower temperatures, the Sr containing alloys exhibit lower flow stress and no fracture in the strain range investigated (40 pct reduction in cylinder height). The textures of the extruded alloys contain two main components named as RD ( c-axis parallel to the radial direction) and HD ( c-axis parallel to the hoop direction) based on their orientation with the sample coordinates. During expansion, extension twinning in the HD grains reorients the lattice to strengthen the RD and form a new ED ( c-axis parallel to the extrusion direction) component. By increasing the temperature or level of Sr, the ED component is weakened due to the decrease in twinning. During expansion, the RD grains undergo contraction and double twining which reduce the overall texture strength.

  8. Hybrid epoxy–silane coatings for improved corrosion protection of Mg alloy

    International Nuclear Information System (INIS)

    Highlights: ► Hybrid epoxy–silane coatings for corrosion protection of Mg alloy AZ31. ► Electrochemical impedance spectroscopy to study the corrosion behavior. ► Very good corrosion protection after 1 month immersion in 0.05 M NaCl. ► Surface and chemical characterization to understand corrosion processes. ► Influence of organic structure in coatings corrosion performance. - Abstract: New hybrid epoxy–silane coatings, with added functionalities for improved performance and durability, were designed to increase the corrosion protection of magnesium alloys. The corrosion behavior of the coated AZ31 was studied through electrochemical impedance spectroscopy (EIS) in 0.05 M NaCl. The morphology and surface chemistry of the samples were also investigated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) before and after immersion in the electrolyte. The new hybrid silane coatings showed a high resistance to corrosion that persisted throughout one-month immersion in a pH-neutral NaCl solution.

  9. Effect of implantation of biodegradable magnesium alloy on BMP-2 expression in bone of ovariectomized osteoporosis rats

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yue, E-mail: 373073766@qq.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Ren, Ling, E-mail: lren@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Liu, Chang, E-mail: meixifan1971@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Yuan, Yajiang, E-mail: yuan925@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Lin, Xiao, E-mail: linx@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Tan, Lili, E-mail: lltan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Chen, Shurui, E-mail: 272146792@qq.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Mei, Xifan, E-mail: meixifan1971@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China)

    2013-10-01

    The study was focused on the implantation of a biodegradable AZ31 magnesium alloy into the femoral periosteal of the osteoporosis modeled rats. The experimental results showed that after 4 weeks implantation of AZ31 alloy in the osteoporosis modeled rats, the expression of BMP-2 in bone tissues of the rats was much enhanced, even higher than the control group, which should promote the bone formation and be beneficial for reducing the harmful effect of osteoporosis. Results of HE stains showed that the implantation of AZ31 alloy did not have obvious pathological changes on both the liver and kidney of the animal. - Highlights: • Mg alloy greatly increased expression of BMP-2 in osteoporosis modeled rat bone. • Mg alloy showed good biological safety. • Mg alloy is beneficial for reducing the symptom of osteoporosis.

  10. Effect of implantation of biodegradable magnesium alloy on BMP-2 expression in bone of ovariectomized osteoporosis rats

    International Nuclear Information System (INIS)

    The study was focused on the implantation of a biodegradable AZ31 magnesium alloy into the femoral periosteal of the osteoporosis modeled rats. The experimental results showed that after 4 weeks implantation of AZ31 alloy in the osteoporosis modeled rats, the expression of BMP-2 in bone tissues of the rats was much enhanced, even higher than the control group, which should promote the bone formation and be beneficial for reducing the harmful effect of osteoporosis. Results of HE stains showed that the implantation of AZ31 alloy did not have obvious pathological changes on both the liver and kidney of the animal. - Highlights: • Mg alloy greatly increased expression of BMP-2 in osteoporosis modeled rat bone. • Mg alloy showed good biological safety. • Mg alloy is beneficial for reducing the symptom of osteoporosis

  11. The influence of the recrystallization mechanisms and grain growth on the texture of a hot rolled AZ31 sheet during subsequent isochronal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Victoria-Hernandez, J., E-mail: jose.victoria-hernandez@hzg.de; Yi, S.; Bohlen, J.; Kurz, G.; Letzig, D.

    2014-12-15

    Highlights: • The rolling texture of a twin roll cast AZ31 shows broad off-basal orientations. • Prismatic and pyramidal slip, and secondary twins influence the rolling texture. • Discontinuous recrystallization is promoted in grains deformed by pyramidal slip. • Recovery and extended recovery are promoted in grains deformed by prismatic slip. • Fast growing grain with orientation close to (0 0 0 1) lead the formation of a basal texture. - Abstract: The texture development during isochronal annealing at 250, 300 and 350 °C for 30 min of a hot rolled Mg AZ31 sheet produced by twin-roll casting was studied in this work. It was found that the rolling texture shows some features that resemble the textures that develop in rolled Mg alloys with rare earth additions. During further heat treatment, special attention was given to the deformation and recrystallization mechanisms, and grain growth that control the texture development. It was found that at 250 and 300 °C extended recovery and discontinuous recrystallization influence the texture by generating strain free grains with off-basal orientation. Conversely, during annealing at 350 °C growth of grains with their c-axis close to the (0 0 0 1) leads to the formation of the well-known basal type texture.

  12. The influence of the recrystallization mechanisms and grain growth on the texture of a hot rolled AZ31 sheet during subsequent isochronal annealing

    International Nuclear Information System (INIS)

    Highlights: • The rolling texture of a twin roll cast AZ31 shows broad off-basal orientations. • Prismatic and pyramidal slip, and secondary twins influence the rolling texture. • Discontinuous recrystallization is promoted in grains deformed by pyramidal slip. • Recovery and extended recovery are promoted in grains deformed by prismatic slip. • Fast growing grain with orientation close to (0 0 0 1) lead the formation of a basal texture. - Abstract: The texture development during isochronal annealing at 250, 300 and 350 °C for 30 min of a hot rolled Mg AZ31 sheet produced by twin-roll casting was studied in this work. It was found that the rolling texture shows some features that resemble the textures that develop in rolled Mg alloys with rare earth additions. During further heat treatment, special attention was given to the deformation and recrystallization mechanisms, and grain growth that control the texture development. It was found that at 250 and 300 °C extended recovery and discontinuous recrystallization influence the texture by generating strain free grains with off-basal orientation. Conversely, during annealing at 350 °C growth of grains with their c-axis close to the (0 0 0 1) leads to the formation of the well-known basal type texture

  13. Propiedades mecánicas de la aleación AZ31 procesada por una ruta eco-sostenible

    Directory of Open Access Journals (Sweden)

    D’Errico, F.

    2013-12-01

    Full Text Available Recently it has been proved that molding of defect-free components of various commercial alloys of magnesium can be carried out succesfully when small amounts of CaO are added to the melt, making unnecessary the use of SF6 coverage. In the case of AZ alloys, this process also remarkably improves their mechanical properties not only by the greater cleaning of alloys but also by the formation of CaAl2 phase. This work, part of the Green project Metallurgy (http://www.green-metallurgy.eu funded by the European Union (LIFE+2009, studies the influence of different CaO additions on the microstructure and mechanical properties of AZ31 Eco-Mg alloy. The alloy was processed by a conventional route involving extrusion of as-cast rods as well as by a powder metallurgy route (PM using chips as starting material. The objective was to analyze the viability of recycling machining chips to manufacture components for the automobile industry and transportation in general, because of its low cost and environmental impact. It has been demostrated that alloys processed from chips exhibit the highest tensile stress values, close to 320 MPa.Recientemente se ha demostrado la posibilidad de fabricar por moldeo, componentes libres de defectos de diferentes aleaciones comerciales de magnesio, añadiendo CaO al caldo, sin emplear SF6. En el caso de las aleaciones AZ este proceso, además, mejora notablemente las propiedades mecánicas, no sólo por la mayor limpieza de las aleaciones sino también por la presencia de la fase CaAl2 que se forma por la incorporación de calcio al caldo. Este trabajo, enmarcado dentro del proyecto Green Metallurgy (http://www.green-metallurgy.eu financiado por la Unión Europea (Programa LIFE+2009, estudia la influencia de diferentes adiciones de CaO en la microestructura y propiedades mecánicas de la aleación Eco-Mg AZ31. El estudio se lleva a cabo en aleaciones AZ31 con 0,5, 1 y 1,5% CaO procesadas por dos rutas diferentes, aleaciones

  14. Fatigue life estimation of ultrasonic spot welded Mg alloy joints

    International Nuclear Information System (INIS)

    Highlights: • Fatigue life test of USWed similar Mg alloy was investigated. • USW joints exhibited a superior fatigue life compared with other welding processes. • Life prediction model agreed fairly well with the obtained experimental results. • The fatigue failure mode changed with decreasing cyclic load level. - Abstract: Lightweight magnesium alloys are increasingly used in automotive and other transportation industries for weight reduction and fuel efficiency improvement. The structural application of magnesium components requires proper welding and fatigue resistance to guarantee their durability and safety. The objective of this investigation was to identify failure mode and estimate fatigue life of ultrasonic spot welded (USWed) lap joints of an AZ31B-H24 magnesium alloy. It was observed that the solid-state USWed joints exhibited a superior fatigue life compared with other welding processes. Fatigue failure mode changed from interfacial failure to transverse-through-thickness crack growth with decreasing cyclic load level, depending on the welding energy. Fatigue crack initiation and propagation occurred from both the notch tip inside the faying surface and the edge of sonotrode indentation-footprints due to the presence of stress concentration. A life prediction model for the spot welded lap joints developed by Newman and Dowling was adopted to estimate the fatigue lives of the USWed magnesium alloy joints. The fatigue life estimation, based on the fatigue crack growth model with the global and local stress intensity factors as a function of kink length and the experimentally determined kink angle, agreed fairly well with the obtained experimental results

  15. The influence of the magnesium alloys microstructure on the cathodic hydrogen evolution

    OpenAIRE

    Габов, А. Л.; Белослудцев, И. С.; Медведева, Н. А.; Скрябина, Н. Е.; Фрушар, Д.; Gabov, A. L.; Belosludtsev, I. S.; Medvedeva, N. A.; Skryabina, N. E.; Fruchart, D.

    2014-01-01

    Evolution of grain structure of magnesium AZ31 and ZK60 alloys during equal channel angular pressing (ECAP) at the 200 ºC temperatures is researched. It is shown that ECAP leads to forming of very inhomogeneous structure. It has been found that deformation affects the rate of the cathodic process. AZ31 alloy is more effective cathode material in alkaline solution environment in comparison with Mg and ZK60 alloys. The object of study were samples of pure magnesium and alloys on its basis – AZ3...

  16. Quasicrystal-reinforced Mg alloys

    International Nuclear Information System (INIS)

    The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg–Zn–Y and Mg–Zn–Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg–Zn–Y alloys, the co-presence of I and Ca2Mg6Zn3 phases by addition of Ca can significantly enhance formability, while in Mg–Zn–Al alloys, the co-presence of the I-phase and Mg2Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg–Zn–Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg–Zn–Al–Sn alloys is attributed to the presence of finely distributed Mg2Sn and I-phase particles embedded in the α-Mg matrix. (review)

  17. Friction Stir Lap Welding of Magnesium Alloy to Steel: A Preliminary Investigation

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Saumyadeep; Hovanski, Yuri; Grant, Glenn J.

    2010-12-01

    An initial study was made to evaluate the feasibility of joining Magnesium alloy AZ31 sheet to galvanized steel sheet in lap configuration using friction stir welding (FSW). Two different automotive sheet steels were used for comparative evaluation of the dissimilar joining potential; a 0.8mm thick, electro galvanized (EG) mild steel, and a 1.5mm thick hot dipped galvanized (HDG) high-strength, low-alloy steel (HSLA). These steels were joined to 2.33mm thick AZ31B magnesium sheet. A single FSW tool design was used for both dissimilar welds, and process parameters were kept the same. Average peak load for the AZ31-1.5 mm steel weld joint in lap shear mode was found to be 6.3 ± 1.0 kN. For the AZ31-0.8 mm steel weld, joint strength was 5.1 ± 1.5 kN. Microstructural investigation indicates melting of the Zn coating at the interface and subsequent alloying with the Mg sheet resulting in formation of solidified Zn-Mg alloy layer at AZ31/steel interface.

  18. Mg Sheet Metal Forming: Lessons Learned from Deep Drawing Li and Y Solid-Solution Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Agnew, Sean R [University of Virginia; Senn, Jeremy W. [University of Virginia; Horton Jr, Joe A [ORNL

    2006-01-01

    The sheet formability of current magnesium alloys at ambient temperatures is poor; however, the formability at moderately elevated temperatures can be excellent. Cylindrical cup drawing tests are used to compare the warm forming characteristics of conventional alloy AZ31B with alloys containing lithium oryttrium solid solutions. While both types of experimental alloy can have better room-temperature ductility ({epsilon}{sub f}-25-30%) than AZ31B, only the lithium alloy has comparable or better deep-drawing capacity. The results are discussed in terms of the sheet anisotropy. Particular attention is drawn to the fact that magnesium alloys exhibit poor bending ductility due to their anisotropy and mechanical twinning-induced tension-compression strength asymmetry.

  19. Bioactive glass–ceramic coating for enhancing the in vitro corrosion resistance of biodegradable Mg alloy

    International Nuclear Information System (INIS)

    Highlights: ► Sol–gel derived 45S5 glass–ceramic coating was prepared on Mg alloy substrate. ► The corrosion resistance of glass–ceramic coated Mg alloy was markedly improved. ► The corrosion behavior of the coated sample varied due to the cracking of coating. - Abstract: In this work, a bioactive 45S5 glass–ceramic coating was synthesized on magnesium (Mg) alloy substrate by using a sol–gel dip-coating method, to improve the initial corrosion resistance of AZ31 Mg alloy. The surface morphology and phase composition of the glass–ceramic coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The coating composed of amorphous phase and crystalline phase Na2Ca2Si3O9, with the thickness of ∼1.0 μm, exhibited a uniform and crack-free surface morphology. The corrosion behavior of the uncoated and coated Mg alloy substrates was investigated by the electrochemical measurements and immersion tests in simulated body fluid (SBF). Potentiodynamic polarization tests recorded an increase of potential (Ecorr) form −1.60 V to −1.48 V, and a reduction of corrosion current density (icorr) from 4.48 μA cm−2 to 0.16 μA cm−2, due to the protection provided by the glass–ceramic coating. Immersion tests also showed the markedly improved corrosion resistance of the coated sample over the immersion period of 7 days. Moreover, after 14 days of immersion in SBF, the corrosion resistance of the coated sample declined due to the cracking of the glass–ceramic coating, which was confirmed by electrochemical impedance spectroscopy (EIS) analysis. The results suggested that the 45S5 glass–ceramic coated Mg alloy could provide a suitable corrosion behavior for use as degradable implants.

  20. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    Directory of Open Access Journals (Sweden)

    Escudero, M. L.

    2011-06-01

    Full Text Available The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair.En el presente trabajo se ha estudiado el comportamiento frente a la corrosión y la biocompatibilidad in vitro/in vivo de la aleación de magnesio AZ31, cuyas propiedades mecánicas son superiores a los requisitos mecánicos del hueso. La aleación en estado de recepción ha mostrado una cinética de corrosión no compatible con el crecimiento celular. Para mejorar su comportamiento, el material ha sido modificado superficialmente mediante tratamiento de conversión química en ácido fluorhídrico. La capa de fluoruro de magnesio generada tras este tratamiento mejora el comportamiento del material frente a la corrosión, permitiendo el crecimiento in vitro de células osteoblásticas sobre su superficie y la formación in vivo de una capa de nuevo tejido óseo muy compacta. Estos resultados permiten concluir que el recubrimiento de fluoruro de magnesio es necesario para que el material AZ31 pueda ser potencialmente aplicado como implante biodegradable y reabsorbible en reparaciones óseas.

  1. Research on the corrosion resistance and formation of double-layer calcium phosphate coating on AZ31 obtained at varied temperatures

    International Nuclear Information System (INIS)

    In this study, the effect of varied processing temperatures on the corrosion resistance and formation of dual-layer calcium phosphate coating on AZ31 was investigated. The microstructure, phase and morphology were characterized by a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometer (XRD), respectively. The in vitro degradation behavior of coated AZ31 samples were evaluated by electrochemical and immersion tests in simulated body fluid. The results showed that the varied processing temperatures responded to different microstructure, phase and morphology; and a dual-layer coating was formed during the deposition process at 70 °C. Meanwhile the higher processing temperature induced a faster coating formation rate and greater surface coverage. The in vitro degradation tests in simulated body fluid indicated that the corrosion rates of AZ31 alloy were effectively decreased with increasing processing temperature, which was attributed to the denser protective coating. The formation mechanism of dual-layer coating influenced by deposition temperature was proposed. - Highlights: • Double-layer Ca–P coating was successfully fabricated on AZ31 alloy by chemical deposition. • Effect of processing temperatures on coating formation and performance was studied. • The coating obtained at 70 °C showed better corrosion resistance by electrochemical and immersion tests. • The formation mechanism of dual-layer coating influenced by deposition temperature was proposed

  2. Structural and tribological properties of CrTiAlN coatings on Mg alloy by closed-field unbalanced magnetron sputtering ion plating

    Science.gov (United States)

    Shi, Yongjing; Long, Siyuan; Yang, Shicai; Pan, Fusheng

    2008-09-01

    In this paper, a series of multi-layer hard coating system of CrTiAlN has been prepared by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. The coatings were deposited onto AZ31 Mg alloy substrates. During deposition step, technological temperature and metallic atom concentration of coatings were controlled by adjusting the currents of different metal magnetron targets. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). The structural, mechanical and tribological properties of coatings were characterized by means of X-ray photoelectron spectrometry, high-resolution transmission electron microscope, field emission scanning electron microscope (FESEM), micro-hardness tester, and scratch and ball-on-disc tester. The experimental results show that the N atomic concentration increases and the oxide on the top of coatings decreases; furthermore the modulation period and the friction coefficient decrease with the N 2 level increasing. The outstanding mechanical property can be acquired at medium N 2 level, and the CrTiAlN coatings on AZ31 Mg alloy substrates outperform the uncoated M42 high speed steel (HSS) and the uncoated 316 stainless steel (SS).

  3. Mechanical property and formability of AZ31B extruded tube at elevated temperature

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mechanical properties of AZ31B magnesium alloy tube were tested by ring hoop tension test at different temperatures.The formability for tube hydroforming was also evaluated by free-expansion test. The results show that there exists a quick decrease of total elongation along hoop direction at the temperature range of 150-230 ℃, which is quite different from that along axial direction. The total elongation along hoop direction of welded tube is quite close to that of seamless tube until 230 ℃ is reached. At higher temperature, the total elongation for seamless tube begins to increase while the value for welded tube continues to decrease.The maximum free expansion ratio of seamless tube increases considerably as temperature increases and reaches the maximum value of 30% at 170 ℃, then decreases quickly at higher temperature.

  4. Corrosion Behavior and Strength of Dissimilar Bonding Material between Ti and Mg Alloys Fabricated by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Patchara Pripanapong

    2016-08-01

    Full Text Available Ti and solution treated Mg alloys such as AZ31B (ST, AZ61 (ST, AZ80 (ST and AZ91 (ST were successfully bonded at 475 °C by spark plasma sintering, which is a promising new method in welding field. The formation of Ti3Al intermetallic compound was found to be an important factor in controlling the bonding strength and galvanic corrosion resistance of dissimilar materials. The maximum bonding strength and bonding efficiency at 193 MPa and 96% were obtained from Ti/AZ91 (ST, in which a thick and uniform nano-level Ti3Al layer was observed. This sample also shows the highest galvanic corrosion resistance with a measured galvanic width and depth of 281 and 19 µm, respectively. The corrosion resistance of the matrix on Mg alloy side was controlled by its Al content. AZ91 (ST exhibited the highest corrosion resistance considered from its corrode surface after corrosion test in Kroll’s etchant. The effect of Al content in Mg alloy on bonding strength and corrosion behavior of Ti/Mg alloy (ST dissimilar materials is discussed in this work.

  5. Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions

    Directory of Open Access Journals (Sweden)

    V. Anes

    2014-10-01

    Full Text Available Components and structures are designed based in their material’s mechanical properties such as Young's modulus or yield stress among others. Often those properties are obtained under monotonic mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained during the material fatigue life. However, under cyclic loadings, materials tend to change their mechanical properties, which can improve their strength (material hardening or degrade their mechanical capabilities (material softening or even a mix of both. This type of material behaviour is the so-called cyclic plasticity that is dependent of several factors such as the load type, load level, and microstructure. This subject is of most importance in design of structures and components against fatigue failures in particular in the case of magnesium alloys. Magnesium alloys due to their hexagonal compact microstructure have only 3 slip planes plus 1 twining plane which results in a peculiar mechanical behaviour under cyclic loading conditions especially under multiaxial loadings. Therefore, it is necessary to have a cyclic elastic-plastic model that allows estimating the material mechanical properties for a certain stress level and loading type. In this paper it is discussed several aspects of the magnesium alloys cyclic properties under uniaxial and multiaxial loading conditions at several stress levels taking into account experimental data. A series of fatigue tests under strain control were performed in hour glass specimens test made of a magnesium alloy, AZ31BF. The strain/stress relation for uniaxial loadings, axial and shear was experimentally obtained and compared with the estimations obtained from the theoretical elastic-plastic models found in the state-of-the-art. Results show that the AZ31BF magnesium alloy has a peculiar mechanical behaviour, which is quite different from the steel one. Moreover, the state of the art cyclic models do not capture in

  6. Antibacterial biodegradable Mg-Ag alloys

    OpenAIRE

    D Tie; F Feyerabend; W-D Müller; Schade, R; Liefeith, K; KU Kainer; Willumeit, R.

    2013-01-01

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solut...

  7. Antibacterial Mg-Ag biodegradable alloys

    OpenAIRE

    Tie, Di

    2013-01-01

    The use of magnesium alloys as degradable metals for biomedical applications is topic of ongoing research. As a further aspect, the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed to combine the favourable properties of magnesium with the wellknown antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag which contain 1.87%, 3.82% and 6.00% silver by weight respectively were casted and processed with solution and ...

  8. Antibacterial biodegradable Mg-Ag alloys

    Directory of Open Access Journals (Sweden)

    D Tie

    2013-06-01

    Full Text Available The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4 and aging (T6 heat treatment.The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH2 and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7, revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231 and Staphylococcus epidermidis (DSMZ 3269, and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  9. Time Dependent Magnesium AZ31B Behavior: Experimental and Physically based Modeling Investigation

    Science.gov (United States)

    Rodriguez, A. K.; Ayoub, G.; Kridli, G.; Zbib, H.

    The need to produce vehicles with improved fuel efficiency and reduced emissions has led the automotive industry to consider use of "lightweighting" materials in the construction of automotive body and chassis systems. For automotive body structures and closure panel applications, mostly made of sheet, aluminum alloys are being introduced due to their lower densities and relatively high specific strengths, as well as their compatibility with the traditional manufacturing process that are used with steel. However, interest has been increasingly focusing on the use of sheet magnesium in the manufacturing of panels and structural components, since its density is about 40% lower compared to aluminum. Accordingly, the objectives of this study are to investigate the evolution of microstructure during thermo-mechanical processing of twin-roll cast AZ31B alloys sheets, and to examine the mechanical properties of the alloy under superplastic conditions. The rate dependent crystal plasticity model have been used and integrated using an explicit model was coupled with the Taylor polycrystal model in the aim to capture the overall behavior of our studied material.

  10. Friction Stir Lap Welding of Magnesium Alloy to Steel: A Preliminary Investigation

    Science.gov (United States)

    Jana, S.; Hovanski, Y.; Grant, G. J.

    2010-12-01

    An initial study was made to evaluate the feasibility of joining magnesium alloy AZ31 sheet to galvanized steel sheet in a lap configuration using friction stir welding (FSW). Two different automotive sheet steels were used for comparative evaluation of the dissimilar joining potential: a 0.8 mm thick, electrogalvanized (EG) mild steel, and a 1.5 mm thick hot-dipped galvanized (HDG) high-strength, low-alloy (HSLA) steel. These steels were joined to 2.33 mm thick AZ31B magnesium sheet. A single FSW tool design was used for both dissimilar welds, and the process parameters were kept the same. The average peak load for the AZ31-1.5 mm steel weld joint in lap shear mode was found to be 6.3 ± 1.0 kN. For the AZ31-0.8 mm steel weld, joint strength was 5.1 ± 1.5 kN. Microstructural investigation indicates melting of the Zn coating present on the steel sheets, and subsequent alloying with the Mg sheet resulted in the formation of a solidified Zn-Mg alloy layer.

  11. Cold Metal Transfer joining of magnesium AZ31B-to-aluminum A6061-T6

    International Nuclear Information System (INIS)

    Automotive manufacturers are faced with increasing pressure to reduce vehicle weight, improve fuel economy, reduce emissions, and enhance vehicle safety and performance. Therefore, an increasing number of vehicle structures are built using a combination of dissimilar materials such as steel, aluminum and magnesium. Though the advantages are potentially huge, this hybrid fabrication approach raises substantial technical challenges to the design of vehicle structures and the associated joining processes. Once two elements (e.g., magnesium–aluminum, aluminum–steel) are mixed in a high temperature welding pool, brittle intermetallic phases (IMP) can be easily formed. Experimental observations showed that a series of intermetallic phases will greatly reduce the mechanical performance of the welded dissimilar materials. In this study, welding of 1 mm thick magnesium AZ31B-to-1 mm thick aluminum A6061-T6 using a 1.6 mm diameter aluminum filler wire 4047 was investigated. Cold Metal Transfer (CMT) arc welding technique was adopted. The key feature of this process is that the motion of the wire has been integrated into the overall control of the process. The wire retraction motion assists droplet detachment during the short circuit, thus the metal can transfer into the welding pool without the aid of the electromagnetic force. In this way the heat input and spatter can be controlled and the IMP formation minimized thereby improving the joint strength. Extensive experiments were performed and analyzed. It was found that although extensive efforts have been exercised to control the heat input, Mg-rich intermetallic γ-Al12Mg17 and Al-rich intermetallic β-Al3Mg2 were still produced in the weld. Fracture surfaces of CMT welded AZ31B–Al6061-T6 joints exhibited the Mg-rich intermetallic (γ-Al12Mg17) which contributes to the weld strength degradation. To improve the joint, minimizing the content of the intermetallics especially Mg-rich intermetallics (γ-Al12Mg17) is

  12. Hydrogen storage systems from waste Mg alloys

    Science.gov (United States)

    Pistidda, C.; Bergemann, N.; Wurr, J.; Rzeszutek, A.; Møller, K. T.; Hansen, B. R. S.; Garroni, S.; Horstmann, C.; Milanese, C.; Girella, A.; Metz, O.; Taube, K.; Jensen, T. R.; Thomas, D.; Liermann, H. P.; Klassen, T.; Dornheim, M.

    2014-12-01

    The production cost of materials for hydrogen storage is one of the major issues to be addressed in order to consider them suitable for large scale applications. In the last decades several authors reported on the hydrogen sorption properties of Mg and Mg-based systems. In this work magnesium industrial wastes of AZ91 alloy and Mg-10 wt.% Gd alloy are used for the production of hydrogen storage materials. The hydrogen sorption properties of the alloys were investigated by means of volumetric technique, in situ synchrotron radiation powder X-ray diffraction (SR-PXD) and calorimetric methods. The measured reversible hydrogen storage capacity for the alloys AZ91 and Mg-10 wt.% Gd are 4.2 and 5.8 wt.%, respectively. For the Mg-10 wt.% Gd alloy, the hydrogenated product was also successfully used as starting reactant for the synthesis of Mg(NH2)2 and as MgH2 substitute in the Reactive Hydride Composite (RHC) 2LiBH4 + MgH2. The results of this work demonstrate the concrete possibility to use Mg alloy wastes for hydrogen storage purposes.

  13. Bioactive glass-ceramic coating for enhancing the in vitro corrosion resistance of biodegradable Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ye Xinyu [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Cai Shu, E-mail: caishu@tju.edu.cn [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Dou Ying [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Xu Guohua [Shanghai Changzheng Hospital, Shanghai 200003 (China); Huang Kai; Ren Mengguo; Wang Xuexin [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Sol-gel derived 45S5 glass-ceramic coating was prepared on Mg alloy substrate. Black-Right-Pointing-Pointer The corrosion resistance of glass-ceramic coated Mg alloy was markedly improved. Black-Right-Pointing-Pointer The corrosion behavior of the coated sample varied due to the cracking of coating. - Abstract: In this work, a bioactive 45S5 glass-ceramic coating was synthesized on magnesium (Mg) alloy substrate by using a sol-gel dip-coating method, to improve the initial corrosion resistance of AZ31 Mg alloy. The surface morphology and phase composition of the glass-ceramic coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The coating composed of amorphous phase and crystalline phase Na{sub 2}Ca{sub 2}Si{sub 3}O{sub 9}, with the thickness of {approx}1.0 {mu}m, exhibited a uniform and crack-free surface morphology. The corrosion behavior of the uncoated and coated Mg alloy substrates was investigated by the electrochemical measurements and immersion tests in simulated body fluid (SBF). Potentiodynamic polarization tests recorded an increase of potential (E{sub corr}) form -1.60 V to -1.48 V, and a reduction of corrosion current density (i{sub corr}) from 4.48 {mu}A cm{sup -2} to 0.16 {mu}A cm{sup -2}, due to the protection provided by the glass-ceramic coating. Immersion tests also showed the markedly improved corrosion resistance of the coated sample over the immersion period of 7 days. Moreover, after 14 days of immersion in SBF, the corrosion resistance of the coated sample declined due to the cracking of the glass-ceramic coating, which was confirmed by electrochemical impedance spectroscopy (EIS) analysis. The results suggested that the 45S5 glass-ceramic coated Mg alloy could provide a suitable corrosion behavior for use as degradable implants.

  14. Fibre Laser Cutting and Chemical Etching of AZ31 for Manufacturing Biodegradable Stents

    Directory of Open Access Journals (Sweden)

    Ali Gökhan Demir

    2013-01-01

    Full Text Available The use of magnesium-alloy stents shows promise as a less intrusive solution for the treatment of cardiovascular pathologies as a result of the high biocompatibility of the material and its intrinsic dissolution in body fluids. However, in addition to requiring innovative solutions in material choice and design, these stents also require a greater understanding of the manufacturing process to achieve the desired quality with improved productivity. The present study demonstrates the manufacturing steps for the realisation of biodegradable stents in AZ31 magnesium alloy. These steps include laser microcutting with a Q-switched fibre laser for the generation of the stent mesh and subsequent chemical etching for the cleaning of kerf and surface finish. Specifically, for the laser microcutting step, inert and reactive gas cutting conditions were compared. The effect of chemical etching on the reduction in material thickness, as well as on spatter removal, was also evaluated. Prototype stents were produced, and the material composition and surface quality were characterised. The potentialities of combining nanosecond laser microcutting and chemical etching are shown and discussed.

  15. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio and a...... low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state are...... discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  16. On the selection of extension twin variants with low Schmid factors in a deformed Mg alloy

    International Nuclear Information System (INIS)

    A statistical analysis is conducted on the formation of {1 0 -1 2} extension twin variants with low Schmid factors (SFs), based on large data sets acquired by electron backscatter diffraction on a deformed Mg AZ31 alloy. Two physical conditions of the analyzed low SF twins are characterized: those solely at grain boundaries (group 1) and those in a pair of cross-boundary twins (group 2). The presence of a majority of them can be explained by strain compatibility arguments. The twins in group 1 require not only the most or more accommodation through basal slip with very low critical resolved shear stress (CRSS), but also the least or less accommodation through pyramidal slip with very high CRSS, in their neighboring grains. Those in group 2 also require the least or less accommodations through pyramidal slip and/or contraction twinning with very high CRSSs, but in their neighboring twins. However, they require the most or more accommodation through prismatic slip and/or extension twinning with low CRSSs. This is due to the texture of the material with respect to the loading geometry that renders different low CRSS accommodation systems available to the two different groups of low SF twins. The shears induced by low SF twins can be accommodated by several different deformation systems. In such cases, twin variant selection criteria depending on only one deformation system are limited in the prediction of twin variants

  17. Effect of Frequency on Fatigue Lifetime of Extruded Mg-3%Al-l%Zn Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHU Rong; WU Yanjun; WANG Jingtao; LI Youyan

    2012-01-01

    Samples prepared from as-extruded magnesium alloy Mg-3%Al-l%Zn (AZ31) billets were utilized in low-cycle fatigue tests in order to investigate the frequency-dependent fatigue life.Fully reversed strain-controlled tension-compression fatigue tests were carried out at frequencies of 1 Hz and 10 Hz in air.The microstructures were examined by optical microscopy (OM) and scanning electron microscopy (SEM).When the strain amplitude was lower than 0.2%,the fatigue life exhibited a positive correlation with loading frequency,and the activity of twinning was increased at 10 Hz.When the strain amplitude was higher than 0.2%,significant twinning was observed both at these two frequencies,and the fatigue life was found to be independent of frequency.The possible reasons for this frequency-related fatigue lifetime may be due to the dependence of twinning upon loading frequency and strain amplitude.

  18. Effect of subsequent tension and annealing on microstructure evolution and strength enhancement of friction stir welded Mg alloys

    International Nuclear Information System (INIS)

    Friction stir welded (FSW) Mg alloys normally exhibit a lower yield strength compared with the base materials, which is a drawback for their application as structure materials. In this study, subsequent tension along the transverse direction (TD) and then annealing were applied on FSW AZ31 alloys to modify the microstructure and texture in weld zone and to improve the joint strength. The results showed that by subsequent tension ∼4.5% strain along TD and then annealing, the yield strength (YS) could be greatly enhanced for the FSW AZ31 alloys. Specifically the YS was improved from ∼86 to ∼177 MPa by subsequent 4.5% tension and then reduced to ∼156 MPa after annealing. For the initial joint sample, fracture occurred in the stir zone (SZ) side during the transverse tensile test. But after subsequent tension, all the samples fractured in the base materials (BMs) whether subjected to annealing or not. The microstructure and texture evolutions after subsequent tension and annealing were examined by electron backscatter diffraction (EBSD) to understand the underlining mechanisms for the improved mechanical properties. It revealed that a lot of {10−12} extension twins were generated in the SZ side by 4.5% tension along TD, which significantly refined the grains in the SZ side and rotated the grains from soft to hard orientations for the transverse tensile test. Therefore, the formation of {10−12} twin lamellae had significant hardening effects on further transverse tensile tests. Schmid factor (SF) analysis revealed that the texture change by subsequent tension had much more impact on the activation of {10−12} extension twinning than basal slip for the transverse tensile test. This might affect the competition of extension twinning and basal slip and reduce the deformation incompatibility in the SZ side, which was beneficial for the improvement of mechanical properties. Nevertheless the present study showed that it was efficient to improve the YS of FSW Mg

  19. Texture Evolution of Single-Pass Hot-Rolled 5052/AZ31/5052 Clad Sheets

    Science.gov (United States)

    Nie, Huihui; Liang, Wei; Yang, Fuqian; Zheng, Liuwei; Li, Xianrong; Fan, Haiwei

    2016-06-01

    Three-layered 5052/AZ31/5052 clad sheets with maximum rolling reductions of 33% and 48% were prepared, using single-pass hot rolling followed by thermal annealing at 200°C for 1 h. The evolutions of microstructures and textures were analyzed. The experimental results show that the AZ31 layer exhibited a typical deformation microstructure with rolling-induced twins. The AZ31 layer with the 33% rolling reduction possessed a texture with the basal pole tilting about 35° away from normal direction to transverse direction and the majority of twins consists of {10 bar{1} 1}-{10 bar{1} 2} double twins and {10 bar{1} 2} tensile twins. The AZ31 layer with the 48% rolling reduction possessed a typical basal texture because {10 bar{1} 1} compression twins were activated by c-axis strain to compete with the tensile twins. No intermetallics were observed after annealing, and recrystallization occurred preferentially at the interface between AZ31 and 5052. The typical rolling texture of the 5052 layer disappeared, and the stable {001} rotation cube component was dominant. The tensile test of the rolled three-layered 5052/AZ31/5052 clad sheets was performed. The tensile experimental results show that the annealed clad sheets with 33% rolling reduction and smaller degree of recrystallization have the largest elongation of 22.5% and larger ultimate tensile strength (UTS) than the annealed clad sheets with 48% rolling reduction.

  20. Creep of Mg-alloys

    Czech Academy of Sciences Publication Activity Database

    Blum, W.; Eisenlohr, P.; Zeng, X. H.; Milička, Karel

    Montreal: Canadian Institute of Mining, Metallurgy and Petroleum, 2006 - (Pekguleryuz, M.; Mackenzie, L.), s. 633-645 ISBN 1-894475-66-6. [Magnesium Technology in the Global Age. Montreal (CA), 01.10.2006-04.10.2006] Institutional research plan: CEZ:AV0Z20410507 Keywords : creep * magnesium alloys * creep mechanisms Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. Recrystallization and texture evolution of Mg-3%Al-1%Zn-(0.4-0.8)%Sr alloys during extrusion

    International Nuclear Information System (INIS)

    Research highlights: → The deformation behavior of a new magnesium alloy system (Mg-Al-Zn-Sr) have been thoroughly analyzed via hot extrusion tests, texture measurements, hot compression tests and extensive microscopy ranging from OM, SEM and TEM on microstructures. → The effect of Sr on formation of deformation texture in the (Mg-Al-Zn-Sr) complex alloy has been determined with X-ray diffraction and verified via EBSD and TEM investigations. → Activation of different dynamic recrystallization micro-mechanisms (grain boundary bulging, particle-stimulated nucleation and twining) at different composition-temperature conditions has been investigated using texture, microstructure and hot compression results. - Abstract: Microstructure and texture evolution during the extrusion of AZ31 magnesium alloy containing 0.4 and 0.8 wt%Sr has been investigated. Following extrusion at 250 deg. C, the microstructure consists of fine recrystallized and large elongated grains along with Al4Sr stringer precipitates. Extrusion at 350 deg. C results in larger and more uniform grain size. Grain refinement and nucleation of new grains were associated with sub-grain formation in the elongated grains, grain boundary bulging, and nucleation at the particle interfaces. Texture measurements in the extrusion deformation zone show an increase in the basal ring fiber-texture from the undeformed zone toward the die opening. Compared to AZ31 without Sr, the texture intensity increases with increasing Sr at 250 deg. C, whereas the strength of extrusion fiber texture decreases at 350 deg. C. The Al solubility in the α-Mg matrix decreases with increasing the Sr and the Al solute atmosphere around the dislocations weakens. Due to the reduction of the solute drag effect, dislocation movement is facilitated and dynamic recrystallization becomes more intensive resulting in strengthening the texture during extrusion at 250 deg. C. The decrease in texture intensity at 350 deg. C extrusion is

  2. Recrystallization and texture evolution of Mg-3%Al-1%Zn-(0.4-0.8)%Sr alloys during extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Alireza, E-mail: Alireza.sadeghi@mail.mcgill.ca [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada); Pekguleryuz, Mihriban [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada)

    2011-01-25

    Research highlights: {yields} The deformation behavior of a new magnesium alloy system (Mg-Al-Zn-Sr) have been thoroughly analyzed via hot extrusion tests, texture measurements, hot compression tests and extensive microscopy ranging from OM, SEM and TEM on microstructures. {yields} The effect of Sr on formation of <10.0> deformation texture in the (Mg-Al-Zn-Sr) complex alloy has been determined with X-ray diffraction and verified via EBSD and TEM investigations. {yields} Activation of different dynamic recrystallization micro-mechanisms (grain boundary bulging, particle-stimulated nucleation and twining) at different composition-temperature conditions has been investigated using texture, microstructure and hot compression results. - Abstract: Microstructure and texture evolution during the extrusion of AZ31 magnesium alloy containing 0.4 and 0.8 wt%Sr has been investigated. Following extrusion at 250 deg. C, the microstructure consists of fine recrystallized and large elongated grains along with Al{sub 4}Sr stringer precipitates. Extrusion at 350 deg. C results in larger and more uniform grain size. Grain refinement and nucleation of new grains were associated with sub-grain formation in the elongated grains, grain boundary bulging, and nucleation at the particle interfaces. Texture measurements in the extrusion deformation zone show an increase in the basal ring fiber-texture from the undeformed zone toward the die opening. Compared to AZ31 without Sr, the texture intensity increases with increasing Sr at 250 deg. C, whereas the strength of extrusion fiber texture decreases at 350 deg. C. The Al solubility in the {alpha}-Mg matrix decreases with increasing the Sr and the Al solute atmosphere around the dislocations weakens. Due to the reduction of the solute drag effect, dislocation movement is facilitated and dynamic recrystallization becomes more intensive resulting in strengthening the texture during extrusion at 250 deg. C. The decrease in texture intensity at

  3. Microstructure and properties of Mg/Al joint welded by gas tungsten arc welding-assisted hybrid ultrasonic seam welding

    International Nuclear Information System (INIS)

    Graphical abstract: Gas tungsten arc welding (GTAW) was introduced into ultrasonic seam welding of Mg and Al dissimilar metals for the first time as shown in (a). The preceding GTAW can preheat the sheet metal to enhance the weldability. Without improving the ultrasonic power, the direct joining of 1 mm thick Al and Mg alloys sheets was accomplished and the maximum lap shear strength was 1 kN at a GTAW current of 30 A, approximately 40% of AZ31B Mg alloy base metal, as shown in (b). - Highlights: • Mg and Al were joined in solid state by hybrid ultrasonic seam welding. • The preceding GTAW heat source enhanced the acoustic bonding effect. • The maximum lap shear strength was 1 kN at a GTAW current of 30 A. - Abstract: A novel gas tungsten arc welding (GTAW) assisted hybrid ultrasonic seam welding MgAZ31B and Al6061 alloy sheets with satisfactory joint strength were successfully achieved using a previous GTAW preheating heat source. The preceding GTAW reduced the sheet hardness but enhanced the acoustic softening effect and materials plasticity. Therefore, the direct joining of 1 mm thick MgAZ31B and Al6061 alloy sheets can be obtained without improving the ultrasonic power. The effect of GTAW current on the microstructure and mechanical properties was investigated. The tensile shear strength of the joint increased with GTAW current up to a maximum strength and then decreased dramatically with higher GTAW current. The maximum lap shear strength was 1 kN at a GTAW current of 30 A, approximately 40% of AZ31B Mg alloy base metal. The failure occurred by interface fracture mode, and the fracture patterns exhibited brittle fracture mode with cleavage facet feature

  4. Hydrogenation properties of Mg-Al alloys

    DEFF Research Database (Denmark)

    Andreasen, Anders

    2008-01-01

    . Further, it is found that the kinetics of hydrogenation, as well dehydrogenation, may be significantly improved by alloying compared to pure Mg. The expense of these improvements of the hydrogenation/dehydrogenation properties is a lower gravimetric hydrogen density in the hydrogenated product, (C) 2008...

  5. Study on biodegradation of the second phase Mg{sub 17}Al{sub 12} in Mg–Al–Zn Alloys: In vitro experiment and thermodynamic calculation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chen [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Yang, Huazhe [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Department of Biophysics, China Medical University, Shenyang 110001 (China); Wan, Peng [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Wang, Kehong [Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Tan, Lili, E-mail: lltan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China)

    2014-02-01

    The in vitro biodegradation behavior of Mg{sub 17}Al{sub 12} as a second phase in Mg–Al–Zn alloys was investigated via electrochemical measurement and immersion test. The Hank's solutions with neutral and acidic pH values were adopted as electrolytes to simulate the in vivo environment during normal and inflammatory response process. Furthermore, the local orbital density functional theory approach was employed to study the thermodynamical stability of Mg{sub 17}Al{sub 12} phase. All the results proved the occurrence of pitting corrosion process with crackings for Mg{sub 17}Al{sub 12} phase in Hank's solution, but with a much lower degradation rate compared with both AZ31 alloy and pure magnesium. Furthermore, a preliminary explanation on the biodegradation behaviors of Mg{sub 17}Al{sub 12} phase was proposed. - Highlights: • Degradation of Mg{sub 17}Al{sub 12} was investigated via experiment and calculations. • Normal and inflammatory response environment were simulated with different pH. • Degradation mechanism of Mg{sub 17}Al{sub 12} second phase and magnesium matrix was discussed.

  6. Synthesis of Al-doped Mg2Si1−xSnx compound using magnesium alloy for thermoelectric application

    International Nuclear Information System (INIS)

    Mg2Si1−xSnx thermoelectric compounds were synthesized through a solid-state reaction at 700 °C between chips of Mg2Sn–Mg eutectic alloy and silicon fine powders. The Al dopants were introduced by employing AZ31 magnesium alloy that contains aluminum. The as-synthesized Mg2Si1−xSnx powders were consolidated by spark plasma sintering at 650–700 °C. X-ray diffraction and scanning electron microscopy revealed that the Mg2Si1−xSnx bulk materials were comprised of Si-rich and Sn-rich phases. Due to the complex microstructures, the electrical conductivities of Mg2Si1−xSnx are lower than Mg2Si. As a result, the average power factor of Al0.05Mg2Si0.73Sn0.27 is about 1.5 × 10−3 W/mK2 from room temperature to 850 K, being less than 2.5 × 10−3 W/mK2 for Al0.05Mg2Si. However, the thermal conductivity of Mg2Si1−xSnx was reduced significantly as compared to Al0.05Mg2Si, which enabled the ZT of Al0.05Mg2Si0.73Sn0.27 to be superior to Al0.05Mg2Si. Lastly, the electric power generation from one leg of Al0.05Mg2Si and Al0.05Mg2Si0.73Sn0.27 were evaluated on a newly developed instrument, with the peak output power of 15–20 mW at 300 °C hot-side temperature. - Highlights: • Aluminium is used as dopant in n-type Mg2(Si,Sn) thermoelectric compounds. • Scrap magnesium alloy is used instead of pure raw material, and ball milling is avoided. • Dual phases of solid solution lower thermal conductivity. • Thermoelectric conversion of one-leg material is demonstrated

  7. Processing, microstructure and mechanical properties of bimodal size SiCp reinforced AZ31B magnesium matrix composites

    Directory of Open Access Journals (Sweden)

    M.J. Shen

    2015-06-01

    Full Text Available The bimodal size SiC particulates (SiCp reinforced magnesium matrix composites with different ratios of micron SiCp and nano SiCp (M-SiCp:N-SiCp = 14.5:0.5, 14:1, and 13.5:1.5 were prepared by semisolid stirring assisted ultrasonic vibration method. The AZ31B alloy and all as-cast SiCp/AZ31B composites were extruded at 350 °C with the ratio of 12:1. Microstructural characterization of the extruded M14 + N1 (M-SiCp:N-SiCp = 14:1 composite revealed the uniform distribution of bimodal size SiCp and significant grain refinement. Optical Microscopy(OM observation showed that, compared with the M14.5 + N0.5 (M-SiCp:N-SiCp = 14.5:0.5 composite, there are more recrystallized grains in M14 + N1 (M-SiCp:N-SiCp = 14:1 and M13.5 + N1.5 (M-SiCp:N-SiCp = 13.5:1.5 composites, but in comparison to the M13.5 + N1.5 composite, the average grain size of the M14 + N1 composite is slightly decreased. The evaluation of mechanical properties indicated that the yield strength and ultimate tensile strength of the M14 + N1 composite were obviously increased compared with other composites.

  8. Magnesium and its alloys as degradable biomaterials: corrosion studies using potentiodynamic and EIS electrochemical techniques

    Directory of Open Access Journals (Sweden)

    Wolf Dieter Müller

    2007-03-01

    Full Text Available Magnesium is potentially useful for orthopaedic and cardiovascular applications. However, the corrosion rate of this metal is so high that its degradation occurs before the end of the healing process. In industrial media the behaviour of several magnesium alloys have been probed to be better than magnesium performance. However, the information related to their corrosion behaviour in biological media is insufficient. The aim of this work is to study the influence of the components of organic fluids on the corrosion behaviour of Mg and AZ31 and LAE442 alloys using potentiodynamic, potentiostatic and EIS techniques. Results showed localized attack in chloride containing media. The breakdown potential decreased when chloride concentration increased. The potential range of the passivation region was extended in the presence of albumin. EIS measurements showed that the corrosion behaviour of the AZ31 was very different from that of LAE442 alloy in chloride solutions.

  9. Improving tensile properties of dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy by low temperature high speed extrusion

    International Nuclear Information System (INIS)

    As-cast Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was extruded at temperatures from 350 °C to 500 °C. We examined the microstructural changes during extrusion at different temperatures to clarify dynamic recrystallization mechanisms during extrusion, and also investigated the effect of extrusion temperature on microstructures and mechanical properties of the alloy. High extrusion exit speed of 60 m/min was successfully achieved at wide range of temperatures from 350 °C to 500 °C even when as-cast dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was used as a billet for the extrusion. The extrusion at low temperature refines grain size and weakens basal texture due to continuous dynamic recrystallization (CDRX) together with double twinning. As a result, the alloy sample extruded at 350 °C exhibits higher tensile proof stress of 206 MPa and higher tensile ductility of 29% than T5-treated 6063 aluminum alloy and commercial AZ31 magnesium alloy even in an as-extruded condition. Furthermore, Hall–Petch coefficient for compressive proof stress is 1.8 times larger than that for tensile one, resulting in improvement of yield stress anisotropy (compressive proof stress/tensile yield stress ratio). - Highlights: • Dilute Mg–Al–Ca–Mn alloy can be extruded at high die-exit speed of 60 m/min. • The extrusion at low temperature refines recrystallized grain size and weakens basal texture. • Grain refining improves mechanical properties of dilute Mg–Al–Ca–Mn alloys

  10. Improving tensile properties of dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy by low temperature high speed extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, T., E-mail: s123055@stn.nagaokaut.ac.jp [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan); Mezaki, T.; Xu, C.; Oh-ishi, K. [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan); Shimizu, K.; Hanaki, S. [Sankyo Tateyama, Inc., Sankyo Material-Company, 8-3, Nagonoe, Imizu, Toyama 934-8515 (Japan); Kamado, S. [Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka 940-2188 (Japan)

    2015-11-05

    As-cast Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was extruded at temperatures from 350 °C to 500 °C. We examined the microstructural changes during extrusion at different temperatures to clarify dynamic recrystallization mechanisms during extrusion, and also investigated the effect of extrusion temperature on microstructures and mechanical properties of the alloy. High extrusion exit speed of 60 m/min was successfully achieved at wide range of temperatures from 350 °C to 500 °C even when as-cast dilute Mg-0.27Al-0.13Ca-0.21Mn (at.%) alloy was used as a billet for the extrusion. The extrusion at low temperature refines grain size and weakens basal texture due to continuous dynamic recrystallization (CDRX) together with double twinning. As a result, the alloy sample extruded at 350 °C exhibits higher tensile proof stress of 206 MPa and higher tensile ductility of 29% than T5-treated 6063 aluminum alloy and commercial AZ31 magnesium alloy even in an as-extruded condition. Furthermore, Hall–Petch coefficient for compressive proof stress is 1.8 times larger than that for tensile one, resulting in improvement of yield stress anisotropy (compressive proof stress/tensile yield stress ratio). - Highlights: • Dilute Mg–Al–Ca–Mn alloy can be extruded at high die-exit speed of 60 m/min. • The extrusion at low temperature refines recrystallized grain size and weakens basal texture. • Grain refining improves mechanical properties of dilute Mg–Al–Ca–Mn alloys.

  11. Changes of the texture and the mechanical properties of the extruded Mg alloy ME21 as a function of the process parameters

    International Nuclear Information System (INIS)

    Research highlights: → Ductility enhancement of the wrought magnesium alloy ME21 compared to the typical magnesium alloy AZ31. → The 'rare earth effect' and particle-stimulated nucleation during recrystallization results in a fine-grained microstructure with an almost randomized crystallographic texture for all conventional indirect extruded products. → The variation of the extrusion parameters billet temperatures, press ratio and the cooling conditions allows the variation of the texture so enabling intermediate strength or enhanced ductility. - Abstract: The wrought magnesium alloy ME21, containing cerium as the main rare earth element, is promising for applications as a structural material in the automotive industry, caused by its relatively good hot workability and enhanced ductility at room temperature. This study presents the influence of the billet temperature, the extrusion ratio and the cooling conditions on the crystallographic texture and the mechanical properties of the ME21 extrusion products. The 'rare earth effect' and the particle stimulated nucleation of recrystallization, caused by Mg12Ce particles, result in a homogeneous fine-grained microstructure and a weak texture with a texture component with its basal plane oriented at an angle of 40-50o to the extrusion direction. This texture favors basal slip and hence improves the room temperature ductility of the extrusion products resulting in an elongation up to 30% under tension and up to 20% under compression.

  12. Corrosion protection of Mg/Al alloys by thermal sprayed aluminium coatings

    International Nuclear Information System (INIS)

    The protective features of thermal sprayed Al-coatings applied on AZ31, AZ80 and AZ91D magnesium/aluminium alloys were evaluated in 3.5 wt.% NaCl solution by electrochemical and gravimetric measurements. The changes in the morphology and corrosion behaviour of the Al-coatings induced by a cold-pressing post-treatment were also examined. The specimens were characterized by scanning electron microscopy, energy dispersive X-ray analysis and low-angle X-ray diffraction. The as-sprayed Al-coatings revealed a high degree of porosity and poor corrosion protection, which resulted in galvanic acceleration of the corrosion of the magnesium substrates. The application of a cold-pressing post-treatment produced more compact Al-coatings with better bonding at the substrate/coating interface and higher corrosion resistance regardless of the nature of the magnesium alloy.

  13. Compressive creep behavior of Mg-Sn binary alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mg-Sn based alloy is one of the potential alloys for application at elevated temperature. The compressive creep behavior of ageing-treated Mg-xSn (x=3%, 5%) alloys was investigated at the temperatures of 423 and 473 K and the stresses from 25 MPa to 35 MPa. When the tin content varies, the ageing-treated Mg-xSn alloys show quite different creep resistance, which are mainly attributed to the size and distribution of Mg2Sn phases in the ageing-treated Mg-xSn alloys. The calculated value of stress exponent,n=6.3, suggests that the compressive creep behavior of the ageing-treated Mg-5%Sn alloy is controlled by dislocation creep at the temperature of 473 K and the stresses from 25 MPa to 35 MPa.

  14. Microstructure and corrosion behavior of Mg-Zn-Ag alloys

    International Nuclear Information System (INIS)

    The majority of Mg components currently in use in the automotive and electronic industries are produced by conventional casting processes. However, there is a strong need to develop new high strength wrought alloys for wide-spread application of Mg alloys in near future. In the present study, new Mg-Zn-Ag alloys were developed and characterized. In order to evaluate the effects of Ag addition on the mechanical properties of the extruded Mg-Zn alloys, the age hardening response and mechanical properties were examined with different amounts of alloying element. The microstructures of the specimens were examined with optical microscopy and transmission electron microscopy. The grain sizes of the alloys in as-extruded condition were markedly reduced with the addition of Ag. The hardness was found to increase more rapidly in the alloys with double aging treatment compared to those with single aging treatment. The peak hardness was also found to be higher in the alloys with double aging treatment. In all heat treatment conditions, the hardnesses of the Mg-Zn-Ag alloys were found to be higher than those of the Mg-Zn alloys. Moreover, the addition of Ag to the Mg-Zn alloys increased the corrosion rate measured by immersion test

  15. Effect of extrusion processing parameters on microstructure and mechanical properties of as-extruded AZ31 sheets

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The AZ31 sheets were prepared by extrusion. The effects of the extrusion processing parameters including the temperature,extrusion ratio, and structure of the extrusion die on the microstructure and mechanical properties of the as-extruded AZ31 sheets were investigated. The results show that the partial grains grow abnormally.and the mechanical and anisotropic properties of the as-extruded AZ31 sheets have little change at the extrusion temperatures of 380-400 ℃ and the extrusion ratio of 13.3. With the increase of the extrusion ratio, the microstructure of the as-extruded AZ31 sheets by conventional die becomes finer and more uniform, and the elongation rate increases, but the strength decreases and its anisotropy becomes worse. Under the porthole die, finer and more uniform microstructure, higher mechanical properties and better anisotropy can be brought for the as-extruded AZ31 sheets.The extruded AZ31 sheets by the porthole die have better anneal process of 300℃ and 1 h.

  16. Atomic-scale investigation of creep behavior in nanocrystalline Mg and Mg-Y alloys

    OpenAIRE

    Bhatia, M. A.; Mathaudhu, S. N.; Solanki, K. N.

    2015-01-01

    Magnesium (Mg) and its alloys offer great potential for reducing vehicular mass and energy consumption due to their inherently low densities. Historically, widespread applicability has been limited by low strength properties compared to other structural Al-, Ti- and Fe-based alloys. However, recent studies have demonstrated high-specific-strength in a number of nanocrystalline Mg-alloys. Even so, applications of these alloys would be restricted to low-temperature automotive components due to ...

  17. 5083 type Al-Mg and 6082 type Al-Mg-Si alloys for ship building

    Directory of Open Access Journals (Sweden)

    Burcu Ertuğ

    2015-03-01

    Full Text Available Marine transport is increasing its use of aluminium by capitalizing on its two leading qualities: lightness and corrosion resistance. The most popular aluminium alloys for use in corrosive environmentssuch as seawater are the 5xxx and 6xxx series alloys, which demonstrate adequate strength and excellent corrosion resistance. The traditional and the most often used Al-alloys in shipbuilding are 5083 type Al-Mg alloy for plates, and 6082 type Al-Mg-Si alloy for extrusions. These alloys were found to be reliable in marine service as well as during manufacturing.

  18. Use of high energy ball milling to study the role of graphene nanoplatelets and carbon nanotubes reinforced magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, Muhammad, E-mail: rashadphy87@gmail.com [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing, Chongqing 401123 (China); Zhang, Jianyue [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Asif, Muhammad [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-10-15

    Graphene nanoplatelets (few layer graphene) and carbon nanotubes were used as reinforcement fillers to enhance the mechanical properties of AZ31 magnesium alloy through high energy ball milling, sintering, and hot extrusion techniques. Experimental results revealed that tensile fracture strain of AZ31 magnesium alloy was enhanced by +49.6% with 0.3 wt.% graphene nanoplatelets compared to −8.3% regression for 0.3 wt.% carbon nanotubes. The tensile strength of AZ31 magnesium alloy was decreased (−11.2%) with graphene nanoplatelets addition, while increased (+7.7%) with carbon nanotubes addition. Unlike tensile test, compression tests showed different trend. The compression strength of carbon nanotubes-AZ31 composite was +51.2% greater than AZ31 magnesium alloy as compared to +0.6% increase for graphene nanoplatelets. The compressive fracture strain of carbon nanotubes-AZ31 composite was decreased (−14.1%) while no significant change in fracture strain of graphene nanoplatelets-AZ31 composite was observed. The X-ray diffraction results revealed that addition of reinforcement particles weaken the basal textures which affect the composite's yield asymmetry. Microstructure evaluation revealed the absence of intermetallic phase formation between reinforcements and matrix. The carbon reinforcements in AZ31 magnesium alloy dissolve and isolate β phases throughout the matrix. The increased fracture strain and mechanical strength of graphene nanoplatelets and carbon nanotubes-AZ31 composites are attributed to large specific surface area of graphene nanoplatelets and stiffer nature of carbon nanotubes respectively. - Highlights: • Powder metallurgy method was used to fabricate magnesium composites. • The AZ31-carbon materials composite were blended using ball milling. • The reinforcement particles weaken the basal texture which affects yield asymmetry of composites. • AZ31-graphene nanoplatelets composite exhibited impressive increase in tensile elongation

  19. Use of high energy ball milling to study the role of graphene nanoplatelets and carbon nanotubes reinforced magnesium alloy

    International Nuclear Information System (INIS)

    Graphene nanoplatelets (few layer graphene) and carbon nanotubes were used as reinforcement fillers to enhance the mechanical properties of AZ31 magnesium alloy through high energy ball milling, sintering, and hot extrusion techniques. Experimental results revealed that tensile fracture strain of AZ31 magnesium alloy was enhanced by +49.6% with 0.3 wt.% graphene nanoplatelets compared to −8.3% regression for 0.3 wt.% carbon nanotubes. The tensile strength of AZ31 magnesium alloy was decreased (−11.2%) with graphene nanoplatelets addition, while increased (+7.7%) with carbon nanotubes addition. Unlike tensile test, compression tests showed different trend. The compression strength of carbon nanotubes-AZ31 composite was +51.2% greater than AZ31 magnesium alloy as compared to +0.6% increase for graphene nanoplatelets. The compressive fracture strain of carbon nanotubes-AZ31 composite was decreased (−14.1%) while no significant change in fracture strain of graphene nanoplatelets-AZ31 composite was observed. The X-ray diffraction results revealed that addition of reinforcement particles weaken the basal textures which affect the composite's yield asymmetry. Microstructure evaluation revealed the absence of intermetallic phase formation between reinforcements and matrix. The carbon reinforcements in AZ31 magnesium alloy dissolve and isolate β phases throughout the matrix. The increased fracture strain and mechanical strength of graphene nanoplatelets and carbon nanotubes-AZ31 composites are attributed to large specific surface area of graphene nanoplatelets and stiffer nature of carbon nanotubes respectively. - Highlights: • Powder metallurgy method was used to fabricate magnesium composites. • The AZ31-carbon materials composite were blended using ball milling. • The reinforcement particles weaken the basal texture which affects yield asymmetry of composites. • AZ31-graphene nanoplatelets composite exhibited impressive increase in tensile elongation

  20. Corrosion resistance of Mg-RE-Zr alloys

    OpenAIRE

    A. Kiełbus; J. Michalska; T. Rzychoń

    2007-01-01

    Purpose: Magnesium alloys are widely used in the automotive and aerospace industries. Data concerning corrosion of Mg alloys are numerous, but those concerning Mg-RE alloys are scarce. In this paper, the corrosion behavior of cast magnesium alloys containing rare earth elements (WE54, WE43 and Elektron21) were investigated by immersion test in 3.5% NaCl for times up to 7 days.Design/methodology/approach: The study was conducted on WE54, WE43 and Elektron 21 alloys in the as-cast condition. I...

  1. Synthesis of Al-doped Mg{sub 2}Si{sub 1−x}Sn{sub x} compound using magnesium alloy for thermoelectric application

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiaokai, E-mail: xiaokai.hu@deakin.edu.au [Institute for Frontier Materials, Deakin University, Geelong, VIC 3217 (Australia); Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Barnett, Matthew R. [Institute for Frontier Materials, Deakin University, Geelong, VIC 3217 (Australia); Yamamoto, Atsushi [Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2015-11-15

    Mg{sub 2}Si{sub 1−x}Sn{sub x} thermoelectric compounds were synthesized through a solid-state reaction at 700 °C between chips of Mg{sub 2}Sn–Mg eutectic alloy and silicon fine powders. The Al dopants were introduced by employing AZ31 magnesium alloy that contains aluminum. The as-synthesized Mg{sub 2}Si{sub 1−x}Sn{sub x} powders were consolidated by spark plasma sintering at 650–700 °C. X-ray diffraction and scanning electron microscopy revealed that the Mg{sub 2}Si{sub 1−x}Sn{sub x} bulk materials were comprised of Si-rich and Sn-rich phases. Due to the complex microstructures, the electrical conductivities of Mg{sub 2}Si{sub 1−x}Sn{sub x} are lower than Mg{sub 2}Si. As a result, the average power factor of Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} is about 1.5 × 10{sup −3} W/mK{sup 2} from room temperature to 850 K, being less than 2.5 × 10{sup −3} W/mK{sup 2} for Al{sub 0.05}Mg{sub 2}Si. However, the thermal conductivity of Mg{sub 2}Si{sub 1−x}Sn{sub x} was reduced significantly as compared to Al{sub 0.05}Mg{sub 2}Si, which enabled the ZT of Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} to be superior to Al{sub 0.05}Mg{sub 2}Si. Lastly, the electric power generation from one leg of Al{sub 0.05}Mg{sub 2}Si and Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} were evaluated on a newly developed instrument, with the peak output power of 15–20 mW at 300 °C hot-side temperature. - Highlights: • Aluminium is used as dopant in n-type Mg{sub 2}(Si,Sn) thermoelectric compounds. • Scrap magnesium alloy is used instead of pure raw material, and ball milling is avoided. • Dual phases of solid solution lower thermal conductivity. • Thermoelectric conversion of one-leg material is demonstrated.

  2. Resistance spot welding of AZ series magnesium alloys: Effects of aluminum content on microstructure and mechanical properties

    International Nuclear Information System (INIS)

    The microstructural evolution of the spot welded AZ31, AZ61 and AZ80 magnesium alloys was studied via optical and scanning electron microscopy. As the Al content of the magnesium base alloy increased from 3 wt% (AZ31) to 6% (AZ61) and 8% (AZ80), columnar to equi-axed dendrite transition and grain refinement in the fusion zone were enhanced. However, the increasing amount of the β-Mg17(Al,Zn)12 phase in the heat affected zone (HAZ) and fusion zone (FZ) resulted in the reduction of the tensile shear strengths of the AZ61 and AZ80 welds compared to those of AZ31 welds. Moreover, in the tensile-shear testing, the AZ61 and AZ80 welds failed in the heat affected zone along the fusion boundary, because micro-cracking occurred preferentially at the interfaces between β particles and Mg matrix. Post-weld solutionizing treatment was found to significantly reduce the quantity of β particles in heat affected and fusion zones of AZ61 and AZ80 welds. This led to an increase in the weld strengths of AZ61 and AZ80 alloys because the heat treatment eliminated the β particles and cracks propagated into the coarse-grained heat affected zone and then base material. For the heat treated welds, grain size was found as a major factor in the failure mode

  3. Resistance spot welding of AZ series magnesium alloys: Effects of aluminum content on microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Niknejad, Seyedtirdad, E-mail: snikneja@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., Waterloo, Ontario, Canada N2l 3G1 (Canada); Liu, Lei [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Lee, Mok-Young [Research Institute of Industrial Science and Technology, Pohang 790-600 (Korea, Republic of); Esmaeili, Shahrzad; Zhou, Norman Y. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave., Waterloo, Ontario, Canada N2l 3G1 (Canada)

    2014-11-17

    The microstructural evolution of the spot welded AZ31, AZ61 and AZ80 magnesium alloys was studied via optical and scanning electron microscopy. As the Al content of the magnesium base alloy increased from 3 wt% (AZ31) to 6% (AZ61) and 8% (AZ80), columnar to equi-axed dendrite transition and grain refinement in the fusion zone were enhanced. However, the increasing amount of the β-Mg{sub 17}(Al,Zn){sub 12} phase in the heat affected zone (HAZ) and fusion zone (FZ) resulted in the reduction of the tensile shear strengths of the AZ61 and AZ80 welds compared to those of AZ31 welds. Moreover, in the tensile-shear testing, the AZ61 and AZ80 welds failed in the heat affected zone along the fusion boundary, because micro-cracking occurred preferentially at the interfaces between β particles and Mg matrix. Post-weld solutionizing treatment was found to significantly reduce the quantity of β particles in heat affected and fusion zones of AZ61 and AZ80 welds. This led to an increase in the weld strengths of AZ61 and AZ80 alloys because the heat treatment eliminated the β particles and cracks propagated into the coarse-grained heat affected zone and then base material. For the heat treated welds, grain size was found as a major factor in the failure mode.

  4. Corrosion resistance of Mg-RE-Zr alloys

    Directory of Open Access Journals (Sweden)

    A. Kiełbus

    2007-03-01

    Full Text Available Purpose: Magnesium alloys are widely used in the automotive and aerospace industries. Data concerning corrosion of Mg alloys are numerous, but those concerning Mg-RE alloys are scarce. In this paper, the corrosion behavior of cast magnesium alloys containing rare earth elements (WE54, WE43 and Elektron21 were investigated by immersion test in 3.5% NaCl for times up to 7 days.Design/methodology/approach: The study was conducted on WE54, WE43 and Elektron 21 alloys in the as-cast condition. Immersion test was performed using not deaerated 3.5% NaCl solution at room temperature. Several specimens were placed in 3.5% NaCl solution for periods of time between one and 7 days. The dissolution rates (mg/cm-2day-1 were determined by weight loss measurements.Findings: Elektron 21 alloy exhibits the highest corrosion rate during the immersion test, while WE54 and WE43 alloys had a similar corrosion behavior. The corrosion rates of WE54 and Elektron 21 alloys incresed lineally with increasing the exposure time in 3.5% NaCl, and that of WE43 was almost unchanged and finally reached maximum value 0.26 mg/cm-2day-1.Research limitations/implications: The knowledge about corrosion behavior of Mg-RE-Zr alloys is currently under evaluation on many speciality applications where lightweight connected with optimum corrosion resistance are requiredPractical implications: The comparative results of corrosion behavior of new Mg-RE-Zr alloys leads to optimum choice of alloy for application in automotive, aircraft and aerospace industries.Originality/value: This paper includes the comparative results of corrosion resistance investigations of new Mg-RE–Zr alloys.

  5. Data set for diffusion coefficients of alloying elements in dilute Mg alloys from first-principles

    Directory of Open Access Journals (Sweden)

    Bi-Cheng Zhou

    2015-12-01

    Full Text Available Diffusion coefficients of alloying elements in Mg are critical for the development of new Mg alloys for lightweight applications. Here we present the data set of the temperature-dependent dilute tracer diffusion coefficients for 47 substitutional alloying elements in hexagonal closed packed (hcp Mg calculated from first-principles calculations based on density functional theory (DFT by combining transition state theory and an 8-frequency model. Benchmark for the DFT calculations and systematic comparison with experimental diffusion data are also presented. The data set refers to “Diffusion coefficients of alloying elements in dilute Mg alloys: A comprehensive first-principles study” by Zhou et al. [1].

  6. Foaming behaviour of Al-Si-Cu-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A. [Kongju National University (Korea). Dept. of Mechanical Engineering; Cho, S.S. [Chungnam National University, Daejeon (Korea). School of Materials Engineering; Lee, H.J. [Hanbat National University, Daejeon (Korea). Dept. of Building Service Engineering

    2004-12-15

    The powder metallurgical route was utilised to obtain the Al-5Si-4Cu-4Mg (alloy 544) and Al-3Si-2Cu-2Mg (alloy 322) foams. Various steps such as centrifugal atomisation, mixing alloy powder and foaming agent (1 wt-%TiH{sub 2}), cold compaction of mixture, hot extrusion and foaming in a preheated furnace were performed. Foaming behaviour of the alloys was investigated by digital microscopy, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) mapping in this study. It was found that alloy 544 takes a shorter period of time to initiate pore nucleation than alloy 322. Alloy 544 had a higher pore growth rate than alloy 322 at the same pre-set furnace temperature. In both alloys, crack-like pore nucleation occurred between aluminium alloy powders elongated in a direction parallel to the extrusion direction. Both alloys showed the same foaming sequence of crack-like pore nucleation, spherical pore growth, coalescence of neighbouring pores and collapse of pores adjacent to the free surface of specimen. The time required to start pore nucleation decreased with the increase of foaming temperature. The cell walls of both alloys consisted of {alpha}-Al phase and eutectic phase. (author)

  7. Aging Behavior of Mg-Y-Zr and Mg-Nd-Zr Cast Alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aging behavior of Mg-3.6Y-0.5Zr and Mg-2.7Nd-0.5Zr alloys was investigated by microhardness measurement and transmission electron microscopy. In the case of Mg-Y-Zr alloy, the presence of β″ phase, a major strengthener, having base centered orthorhombic structure with its lattice constants of aβ″=0.64 nm, bβ″=2.22 nm,and cβ″=0.52 nm was identified. In the case of Mg-Nd-Zr alloy aged at 250℃, the presence ofβ″ and β′phases was identified. The crystal structure ofβ″ phase was found to be DO19 and its orientation relationships with Mg matrix were [0001]β″//[0001]Mg and [01-10]β″//[0110]Mg. The β′ phase had face centered cubicstructure and its orientation relationships with Mg matrix were [011]β′//[0001]Mg and [-11-1]β′//[-2110]Mg.The Mg-2.7Nd-0.5Zr alloy showed higher hardness compared with Mg-3.6Y-0.5Zr alloy.

  8. Thermal Microstructural Stability of AZ31 Magnesium after Severe Plastic Deformation

    Energy Technology Data Exchange (ETDEWEB)

    Young, John P.; Askari, Hesam A.; Hovanski, Yuri; Heiden, Michael J.; Field, David P.

    2015-03-01

    Both equal channel angular pressing and friction stir processing have the ability to refine the grain size of twin roll cast AZ31 magnesium and potentially improve its superplastic properties. This work used isochronal and isothermal heat treatments to investigate the microstructural stability of twin roll cast, equal channel angular pressed and friction stir processed AZ31 magnesium. For both heat treatment conditions, it was found that the twin roll casted and equal channel angular pressed materials were more stable than the friction stir processed material. Calculations of the grain growth kinetics showed that severe plastic deformation processing decreased the activation energy for grain boundary motion with the equal channel angular pressed material having the greatest Q value of the severely plastically deformed materials and that increasing the tool travel speed of the friction stir processed material improved microstructural stability. The Hollomon-Jaffe parameter was found to be an accurate means of identifying the annealing conditions that will result in substantial grain growth and loss of potential superplastic properties in the severely plastically deformed materials. In addition, Humphreys’s model of cellular microstructural stability accurately predicted the relative microstructural stability of the severely plastically deformed materials and with some modification, closely predicted the maximum grain size ratio achieved by the severely plastically deformed materials.

  9. Interaction of hydrogen with an Mg-Al alloy (poster)

    DEFF Research Database (Denmark)

    Andreasen, A.; Andreasen, J.W.; Burkarl, R.;

    2004-01-01

    energy for dehydrogenation of the Mg-Al alloy is found to be approx. 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg.Furthermore, it is found that Mg-Al is hydrogenated to MgH2 + Al and upon dehydrogenation a Mg-Al alloy is reformed. Pure Mg is not observed during...... dehydrogenation, suggesting that the formation of Mg-Al is fast compared to the liberation of hydrogen fromMgH2. From thermodynamical calculations using the semi-empirical Miedema model a slightly lower heat of hydride formation is found. Based on comparison with previous experiments on Mg exposed to air it is...

  10. Mg/Cu异种材料共晶反应钎焊连接研究%Dissimilar Metals Between Copper and Magnesium Alloy in Eutectic Contacting Reaction Brazing

    Institute of Scientific and Technical Information of China (English)

    王怀建; 袁苗达; 白莉

    2012-01-01

    Magnesium alloy (AZ31B) and Copper (T2) were bonded by eutectic contacting reaction brazing. The microstructural features and mechanical properties of the welded joint was studied by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). The results show that when the welding process is at 500 °C for 5 min, under the pressure of 2MPa, the tensile strength of the welded joint reaches 42MPa.%采用共晶钎焊工艺对Mg/Cu异种材料进行连接,焊后利用扫描电镜和EDS对焊接接头的微观组织及元素扩散行为进行了研究.在焊接温度为500℃,焊接时间为5min,焊接压力为2MPa的工艺下,焊接接头最高抗拉强度为42 MPa.

  11. Influence of Mg Content on Deformability of AlMg Alloys during Extrusion

    Directory of Open Access Journals (Sweden)

    Leśniak D.

    2016-03-01

    Full Text Available In this study the research on deformability of AlMg alloys with high Mg contents in extrusion was carried out. The different shapes from AlMg alloys containing 3.5%, 4.5% and 5.5% of Mg were extruded on 500 T semi-industrial press by using one-hole and multi-hole flat dies. The extrudates surface quality was under investigations in relation with the temperature-speed parameters of the extrusion process. The metal exit speed was estimated depending on the extrudates shape, wall thickness and Mg content. The alloy’s border solidus and liquidus temperatures were also determined.

  12. Development of Mg-based Hydrogen Storage Alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Mg-based hydrogen storage alloys are considered as a promising candidate for hydrogen system because of its lightweight, high storage capacity, low price and rich mineral resources. In detail,we reviewed the preparation and properties of Mg-Ni-based hydrogen storage alloys. All kinds of attempts have been done to improve the hydriding and dehydriding behaviors. It is found that the partial substitution of foreign elements can decrease the hydrogen absorption temperature,especially the substitution of a more electronegative element, such as Al and Mn. Mechanical alloying (MA) and mechanical grinding (MG) are the most effective methods to improve the hydriding/dehydriding kinetics and electrochemical capacity, and decrease the desorption temperature, but the corrosion resistance is so poor that the 80% of maximum capacity is lost within ten cycles. Microencapsulation is a useful measurement for improving the corrosion resistance and electrocatalytic activity. In order to improve the properties of the alloys for practical application, the alloys should have a large number of defects, which give activated sites, subsequently,MA, MG and electroless plating should be used to improve the hydriding/dehydriding kinetics and protect the surface of alloys, respectively. The new composite Mg-based alloys give a new way for the hydrogen storage material to practical application. Furthermore we put forward several problems which will be discussed in future.

  13. A preliminary study for novel use of two Mg alloys (WE43 and Mg3Gd).

    Science.gov (United States)

    Guo, Yu; Liu, Weiwei; Ma, Shanshan; Wang, Jia; Zou, Jingting; Liu, Zhenzhen; Zhao, Jinghui; Zhou, Yanmin

    2016-05-01

    In this study, two types of magnesium alloys (WE43 and Mg3Gd) were compared with Heal-All membrane (a biodegradable membrane used in guided bone regeneration) in vitro to determine whether the alloys could be used as biodegradable membranes. Degradation behavior was assessed using immersion testing with simulated body fluid (SBF). Microstructural characteristics before and after immersion were evaluated through scanning electron microscopy, and degradation products were analyzed with energy dispersive spectrometry (EDS). To evaluate the biocompatibility of the three types of materials, we performed cytotoxicity, adhesion, and mineralization tests using human osteoblast-like MG63 cells. Immersion testing results showed no significant difference in degradation rate between WE43 and Mg3Gd alloys. However, both Mg alloys corroded faster than the Heal-All membrane, with pitting corrosion as the main corrosion mode for the alloys. Degradation products mainly included P- and Ca-containing apatites on the surface of WE43 and Mg3Gd, whereas these apatites were rarely detected on the surface of the Heal-All membrane. All three type of materials exhibited good biocompatibility. In the mineralization experiment, the alkaline phosphatase (ALP) activity of 10 % Mg3Gd extract was significantly higher than the extracts of the two other materials and the negative control. This study highlighted the potential of these Mg-REE alloys for uses in bone regeneration and further studies and refinements are obviously required. PMID:26968757

  14. Microstructure and properties of Mg-Al binary alloys

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wei-chao; LI Shuang-shou; TANG Bin; ZENG Da-ben

    2006-01-01

    The effects of different amounts of added Al, ranging from 1% to 9%, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  15. Microstructure and properties of Mg-Al binary alloys

    Directory of Open Access Journals (Sweden)

    ZHENG Wei-chao

    2006-11-01

    Full Text Available The effects of different amounts of added Al, ranging from 1 % to 9 %, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  16. Strength modelling of Al-Cu-Mg Type alloys

    OpenAIRE

    Yan, Jialin

    2006-01-01

    Age hardening of Al-Cu-Mg type alloys occurs in two stages separated by a constant hardness plateau when the alloys are aged at 110°C to 240?C after solution treatment and quenching. This work aims to develop a physically based two-stage hardening model to predict the yield strength of Al-Cu-Mg alloys with compositions in the (?+S) phase region. Experiments by means of hardness and tensile tests, differential scanning calorimetry and transmission electron microscopy (TEM) have been carried ou...

  17. First-principles density functional calculations for Mg alloys: A tool to aid in alloy development

    International Nuclear Information System (INIS)

    In studying the thermodynamics and phase stability of Mg alloys, one is often confronted with the lack of accurate, quantitative experimental data. This deficiency can be partially rectified via first-principles calculations based on density functional theory. In this paper, we will illustrate the utility of first-principles energetics for Mg alloys using three case studies (i) formation energies of ordered/disordered solid phases; (ii) solute-vacancy binding energies in Mg; (iii) point defect formation energies of β-Mg17Al12. These first-principles calculations can provide highly accurate thermodynamic and kinetic information for Mg alloys.

  18. Composition Range of Amorphous Mg-Ni-Y Alloys

    Institute of Scientific and Technical Information of China (English)

    陈红梅; 钟夏平; 欧阳义芳

    2003-01-01

    Based on the thermodynamic point of view, a method for predication of the composition range of amorphous ternary alloys was proposed. The composition range of amorphous ternary alloys is determined by the comparison of the excess free energy of the amorphous alloy and the free energy of competing crystalline states. The free energy is extrapolated from the data of three binary alloys by using Toop′s model. The method was applied to predict the composition range of amorphous Mg-Ni-Y alloys. The theoretical results are in good agreement with the available experimental results. It indicates that the present method can be used to predict the composition range for amorphous ternary alloys.

  19. Melt Protection of Mg-Al Based Alloys

    Directory of Open Access Journals (Sweden)

    María J. Balart

    2016-05-01

    Full Text Available This paper reports the current status of Mg melt protection in view to identify near-future challenges, but also opportunities, for Mg melt protection of Mg-Al based alloys. The goal is to design and manufacture sustainable Mg alloys for resource efficiency, recycling and minimising waste. Among alternative cover gas technologies for Mg melt protection other than SF6: commercially available technologies containing―HFC-134a, fluorinated ketone and dilute SO2―and developed technologies containing solid CO2, BF3 and SO2F2, can potentially produce toxic and/or corrosive by-products. On the other hand, additions of alkaline earth metal oxides to Mg and its alloys have developed a strong comparative advantage in the field of Mg melt protection. The near-future challenges and opportunities for Mg-Al based alloys include optimising and using CO2 gas as feedstock for both melt protection and grain refinement and TiO2 additions for melt protection.

  20. Existing form and effect of zirconium in pure Mg, Mg-Yb, and Mg-Zn-Yb alloys

    Institute of Scientific and Technical Information of China (English)

    YU Wenbin; HE Hong; LI Chunmei; LI Qing; LIU Zhiyi; QIN Bing

    2009-01-01

    The existing form and grain refining effects of small zirconium addition in pure Mg, Mg-Yb and Mg-Zn binary alloys, and Mg-Zn-Yb ternary alloy (ZK60-Yb) were investigated. The results show that Zr element exists mainly in single and cluster particles of pure α-Zr or Zn-Zr compounds inside grains and at grain boundaries. Only the particles located in the interior of grains can act as the nucleus for α-Mg growth and effectively promote the formation of Fine equiaxed grains. The broken and dispersed Zr-rich particles produced during the hot extrusion process can form nebulous banded structure in which these free particles may act as obstacles to dislocation motion in wrought magnesium alloys.

  1. Residual stress induced by cold spray coating of magnesium AZ31B extrusion

    International Nuclear Information System (INIS)

    Highlights: • Successful cold spray coating of aluminum powder on magnesium substrate. • Numerical modeling of local plasticity induced by coating on magnesium. • Sensitivity analysis of coating parameters on residual stress distribution. • Procedure for obtaining optimum coating parameters. - Abstract: Aluminum particles were successfully sprayed on wrought magnesium AZ31B extrusion using the cold spray technology. Cold spray high impact velocity of particles colliding with the substrate induced beneficial compressive residual stresses. Magnitude of the residual stress at the surface and its distribution through the thickness were measured using X-ray diffraction. With particle spraying velocity of 400 m/s, the residual stress was measured to be −25 MPa at the surface. The process of collision and development of residual stress was then modeled using LS-DYNA software to study the effect of the cold spray process parameters on the residual stress profile. Various models were employed to simulate the impact of the single and multiple particles. An asymmetric material model that considers the strain rate effect was employed to model AZ31B different behavior in tension and compression. Results of simulations for impact of multiple particles were compared with the results of XRD measurements on the substrate surface and through the depth of the substrate. After the validation of the models, a parametric study was performed on the impact of a single particle to find the optimum cold spray particle velocity, size, shape, incident angle, and friction parameters. Parameters leading to the optimum residual stress profile are introduced herein

  2. 等通道转角挤压制备7075Al/AZ31复合板界面组织及结合强度%Interfacial microstructure and bonding strength of 7075Al/AZ31 composite plates fabricated by equal channel angular pressing

    Institute of Scientific and Technical Information of China (English)

    任广笑; 王红霞; 周斌; 刘一鸣; 王斌兵

    2016-01-01

    在573 K,通过等通道转角挤压成功制备了7075 Al/AZ31复合板,并采用SEM、EDS、XRD和剪切实验研究了挤压道次及退火温度对复合板界面层组织和性能的影响及剪切断裂面的组成.结果表明:1道次等通道转角挤压制备的复合板界面处形成厚度为20μm均匀致密的扩散层,由Al3Mg2相和Mg17Al12相组成,Al3 Mg2相层厚(17 μm)是Mg17Al12相层厚(3μm)的5.6倍.2道次等通道挤压后,扩散层厚度无变化,但是出现了裂纹,剪切强度大幅下降,剪切断裂面发生在Al3Mg3相层.复合板界面层在473 K退火,扩散层厚度无变化,裂纹无改善,剪切强度略有提高;573 K退火,复合板扩散层中的Al3 Mg2相层和β-Mg17Al12相层均急剧增厚,微裂纹被焊合,剪切强度均大幅下降.在相同处理状态下,1道次ECAP复合板剪切强度均高于2道次ECAP复合板,473 K退火处理后,强度高出30.11%.573 K退火处理后,强度高出12.4%.故利用等通道转角挤压法制备7075Al/AZ31复合板,1道次比较合适,扩散层退火温度不宜超过473 K.%7075Al/AZ31 laminated composites were successfully fabricated by equal channel angular processing (ECAP) at 573 K.The effect of ECAP passes arid annealing temperature on microstructure evolution,phase constituent and bonding strength near the joining interface of the laminated composites was studied by means of scanning electron microscopy,X-ray diffraction and shear tests.The results indicate that diffusion layer with thickness of 20 μm is observed at the joining interface of the laminated composites prepared by one ECAP pass.The diffusion layer is mainly composed of Al3Mg2 and β-Mg17Al12 phases.After two ECAP passes,the change of the diffusion layer thickness is not obvious,while the formation of crack in the diffusion layer leads to the bonding strength decreasing.After annealing at 473 K,the thickness of the diffusion layer and the crack remains unchange,while the bonding strength increass

  3. Property Criteria for Automotive Al-Mg-Si Sheet Alloys

    Directory of Open Access Journals (Sweden)

    Ramona Prillhofer

    2014-07-01

    Full Text Available In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deployment of these alloys as an outer panel material. Strength in service was also tested after a simulated paint bake cycle of 20 min at 185 °C, and the corrosion behavior was analyzed. The study showed that forming behavior is strongly dependent on the type of alloy and that it is influenced by the storage period after sheet production. Alloy AA6016 achieves the highest surface quality, and pre-ageing of alloy AA6013 facilitates superior strength in service. Corrosion behavior is good in AA6005A, AA6063 and AA6016, and only AA6013 shows a strong susceptibility to intergranular corrosion. The results are discussed below with respect to the chemical composition, microstructure and texture of the Al-Mg-Si alloys studied, and decision-making criteria for appropriate automotive sheet alloys for specific applications are presented.

  4. Local plastic strain inhomogeneity in a ZEK100 Mg alloy

    Directory of Open Access Journals (Sweden)

    Sinclair C.W.

    2013-11-01

    Full Text Available Magnesium alloys have great potential for lightweighting applications in the transportation industry. It is known, however, that Mg and Mg-alloys exhibit large plastic strain heterogeneity. Such heterogeneity is important both from the perspective of formability and fracture if such sheet materials are to be stamped. Also, such observations are important for our fundamental understanding of how plasticity spreads in such materials. In this work we have sought to couple together local plastic strain measurements using digital image correlation with full-field crystal plasticity simulations with the idea of identifying and quantifying the plastic strain heterogeneity. A recently developed ZEK-100 alloy has been studied, as this alloy has shown promise as a wrought sheet product.

  5. Metallurgical Joining of Magnesium Alloys by the FSW Process

    Directory of Open Access Journals (Sweden)

    Tomáš Kupec

    2012-01-01

    Full Text Available This paper deals with welding AZ 31Mg alloy by FSW (Friction Stir Welding technology. Welds were fabricated with new equipment supplied from China for VUZ-PI Bratislava (Welding Research Institute — Industrial Institute. Welding parameters and conditions were proposed and tested. Joint quality was assessed by optical microscopy and microhardness measurements. The fabricated joints were sound, apart from minor inhomogeneities (cracks. It is considered that after certain adaptations of the welding parameters, and perhaps also of the welding tool, that this equipment will be capable of producing welded joints of excellent quality that can compete with any fusion welding technologies, including concentrated power sources.

  6. Improved Mg-based alloys for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Sapru, K.; Ming, L.; Stetson, N.T.; Evans, J. [Energy Conversion Devices, Inc., Troy, MI (United States)

    1998-08-01

    The overall objective of this on-going work is to develop low temperature alloys capable of reversibly storing at least 3 wt.% hydrogen, allowing greater than for 2 wt.% at the system level which is required by most applications. Surface modification of Mg can be used to improve its H-sorption kinetics. The authors show here that the same Mg-transition metal-based multi-component alloy when prepared by melt-spinning results in a more homogeneous materials with a higher plateau pressure as compared to preparing the material by mechanical grinding. They have also shown that mechanically alloyed Mg{sub 50}Al{sub 45}Zn{sub 5} results in a sample having a higher plateau pressure.

  7. Texture evolution during cold rolling of dilute Mg alloys

    International Nuclear Information System (INIS)

    Effects of alloying additions on deformation texture in Mg sheet alloys are still controversial. In this study, a quasi-in-situ electron backscatter diffraction method is used for the first time to monitor the texture evolution during the cold rolling process of Mg–Zn–Ca and Mg–Zn alloys. It is found that the Ca addition does not cause any texture weakening effect — it only delays the development of a strong basal texture by reducing the growth of deformation twins

  8. High-Strength Low-Alloy (HSLA) Mg-Zn-Ca Alloys with Excellent Biodegradation Performance

    Science.gov (United States)

    Hofstetter, J.; Becker, M.; Martinelli, E.; Weinberg, A. M.; Mingler, B.; Kilian, H.; Pogatscher, S.; Uggowitzer, P. J.; Löffler, J. F.

    2014-04-01

    This article deals with the development of fine-grained high-strength low-alloy (HSLA) magnesium alloys intended for use as biodegradable implant material. The alloys contain solely low amounts of Zn and Ca as alloying elements. We illustrate the development path starting from the high-Zn-containing ZX50 (MgZn5Ca0.25) alloy with conventional purity, to an ultrahigh-purity ZX50 modification, and further to the ultrahigh-purity Zn-lean alloy ZX10 (MgZn1Ca0.3). It is shown that alloys with high Zn-content are prone to biocorrosion in various environments, most probably because of the presence of the intermetallic phase Mg6Zn3Ca2. A reduction of the Zn content results in (Mg,Zn)2Ca phase formation. This phase is less noble than the Mg-matrix and therefore, in contrast to Mg6Zn3Ca2, does not act as cathodic site. A fine-grained microstructure is achieved by the controlled formation of fine and homogeneously distributed (Mg,Zn)2Ca precipitates, which influence dynamic recrystallization and grain growth during hot forming. Such design scheme is comparable to that of HSLA steels, where low amounts of alloying elements are intended to produce a very fine dispersion of particles to increase the material's strength by refining the grain size. Consequently our new, ultrapure ZX10 alloy exhibits high strength (yield strength R p = 240 MPa, ultimate tensile strength R m = 255 MPa) and simultaneously high ductility (elongation to fracture A = 27%), as well as low mechanical anisotropy. Because of the anodic nature of the (Mg,Zn)2Ca particles used in the HSLA concept, the in vivo degradation in a rat femur implantation study is very slow and homogeneous without clinically observable hydrogen evolution, making the ZX10 alloy a promising material for biodegradable implants.

  9. Phase formation in Mg-Sn-Si and Mg-Sn-Si-Ca alloys

    International Nuclear Information System (INIS)

    Research highlights: → The solidification paths of ternary and quaternary alloys are analyzed in detail, using the tool of thermodynamic calculations. → The precipitation sequence of phases and their amounts compare well with the microstructure of alloys. → The most efficient comparison to the experimental thermal analysis data is done by calculation of the enthalpy variation with temperature. → The viability of a procedure for the selection of multicomponent key samples is demonstrated for the development of the Mg-Ca-Si-Sn phase diagram. - Abstract: Experimental work is done and combined with the Calphad method to generate a consistent thermodynamic description of the Mg-Ca-Si-Sn quaternary system, validated for Mg-rich alloys. The viability of a procedure for the selection of multicomponent key samples is demonstrated for this multicomponent system. Dedicated thermal analysis with DTA/DSC on sealed samples is performed and the microstructure of slowly solidified alloys is analyzed using SEM/EDX. The thermodynamic description and phase diagram of the ternary Mg-Si-Sn system, developed in detail also in this work, deviates significantly from a previous literature proposal. The phase formation in ternary and quaternary alloys is analyzed using the tool of thermodynamic equilibrium and Scheil calculations for the solidification paths and compared with present experimental data. The significant ternary/quaternary solid solubilities of pertinent intermetallic phases are quantitatively introduced in the quaternary Mg-Ca-Si-Sn phase diagram and validated by experimental data.

  10. Dissimilar ultrasonic spot welding of Mg-Al and Mg-high strength low alloy steel

    OpenAIRE

    Patel, V K; D. L. Chen; S.D. Bhole

    2014-01-01

    Sound dissimilar lap joints were achieved via ultrasonic spot welding (USW), which is a solid-state joining technique. The addition of Sn interlayer during USW effectively blocked the formation of brittle al12Mg17 intermetallic compound in the Mg-Al dissimilar joints without interlayer, and led to the presence of a distinctive composite-like Sn and Mg2Sn eutectic structure in both Mg-Al and Mg-high strength low alloy (HSLA) steel joints. The lap shear strength of both types of dissimilar join...

  11. Divorced Eutectic Solidification of Mg-Al Alloys

    Science.gov (United States)

    Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo

    2015-08-01

    We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed -Mg phase followed by the nucleation of the -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.

  12. The Age-Precipitations Structure Of Al-Mg-Ge Alloy Aged At 473K

    OpenAIRE

    Kawai A.; Watanabe K; Matsuda K.; Ikeno S.

    2015-01-01

    The Al-Mg-Ge alloy is one of the age-hardening aluminum alloy after solution heat treatment. It has been proposed that the age-precipitation behavior of Al-Mg-Ge alloy is different from that of Al-Mg-Si alloy according to our previous works about the microstructure on Al-Mg-Ge alloy over-aged at 523K. For example, The hardness of peak aged Al-1.0mass%Mg2Ge alloy is higher than that of Al-1.0mass%Mg2Si alloy. The precipitates in the over-aged samples have been classified as some metastable pha...

  13. Energy band bowing parameter in MgZnO alloys

    International Nuclear Information System (INIS)

    We report on bandgap bowing parameters for wurtzite and cubic MgZnO alloys from a study of high quality and single phase films in all Mg content range. The Mg contents in the MgZnO films were accurately determined using the energy dispersive spectrometer and X-ray photoelectron spectroscopy (XPS). The measurement of bandgap energies by examining the onset of inelastic energy loss in core-level atomic spectra from XPS is proved to be valid for determining the bandgap of MgZnO films. The dependence of the energy bandgap on Mg content is found to deviate downwards from linearity. Fitting of the bandgap data resulted in two bowing parameters of 2.01 ± 0.04 eV and 1.48 ± 0.11 eV corresponding to wurtzite and cubic MgZnO films, respectively

  14. Influence of alloying elements and microstructure on the formation of hydrotalcite film on Mg alloys

    International Nuclear Information System (INIS)

    Highlights: • A hydrotalcite film has been formed on Al-free Mg alloys by in situ growth method. • The influence of alloying elements on the composition of the films is discussed. • The role of microstructure in the formation of hydrotalcite film is illustrated. - Abstract: The influence of alloying elements and microstructure of Mg substrates on the formation of hydrotalcite film has been investigated. It is found that the two-step process is also available for the pure Mg and other alloys after modification. A small amount of Zn does not impact the composition of the hydrotalcite film much; whereas the highly active rare earth (RE) affects the constituents of the precursor film as well as the final film on WE54 alloy significantly. The microstructure impacts the initial nucleation and the film morphology depending on the size and chemical activity of the intermetallic particles

  15. Characterization of the microstructure in Mg based alloy

    KAUST Repository

    Kutbee, Arwa T

    2013-06-01

    The cast products Mg–Sn based alloys are promising candidates for automobile industries, since they provide a cheap yet thermally stable alternative to existing alloys. One drawback of the Mg–Sn based alloys is their insufficient hardness. The hardenability can be improved by engineering the microstructure through additions of Zn to the base alloy and selective aging conditions. Therefore, detailed knowledge about the microstructural characteristics and the role of Zn to promote precipitation hardening is essential for age hardenable Mg-based alloys. In this work, microstructural investigation of the Mg–1.4Sn–1.3Zn–0.1Mn (at.%) precipitation system was performed using TEM. The chemical composition of the precipitates was analyzed using EDS. APT was employed to obtain precise chemical information on the distribution of Zn in the microstructure. It was found from microstructural studies that different precipitates with varying sizes and phases were present; lath-shaped precipitates of the Mg2Sn phase have an incoherent interface with the matrix, unlike the lath-shaped MgZn2 precipitates. Furthermore, nano-sized precipitates dispersed in the microstructure with short-lath morphology can either be enriched with Sn or Zn. On the other hand, APT analysis revealed the strong repulsion between Sn and Zn atoms in a portion of the analysis volume. However, larger reconstruction volume required to identify the role of Zn is still limited to the optimization of specimen preparation.

  16. Phase field simulation of equiaxed solidification in technical alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boettger, B. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany); Eiken, J. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany); Steinbach, I. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany)]. E-mail: I.Steinbach@access.rwth-aachen.de

    2006-06-15

    It is shown how the phase field method can be applied to simulate the equiaxed solidification of commercial alloys in technical processes. A multicomponent multiphase field model is coupled to thermodynamic databases. To handle the complex phase diagrams a local quasi-binary extrapolation is applied. Nucleation is treated by statistically distributed seed particles, taking into account the shielding of nucleation sites by recalescence, solute diffusion and growth of solid phases. To reduce computation time it is discussed how three-dimensional phenomena can be approximated by two-dimensional simulations, and the model for latent heat release is adjusted accordingly. As examples, simulations are presented of the commercial Mg-Al-Zn alloy AZ31, a hypereutectic Al-Si-Cu-Mg-Ni piston alloy and AlCu{sub 4}Si{sub 17}Mg.

  17. Biodegradable poly(lactide-co-glycolide) coatings on magnesium alloys for orthopedic applications.

    Science.gov (United States)

    Ostrowski, Nicole J; Lee, Boeun; Roy, Abhijit; Ramanathan, Madhumati; Kumta, Prashant N

    2013-01-01

    Polymeric film coatings were applied by dip coating on two magnesium alloy systems, AZ31 and Mg4Y, in an attempt to slow the degradation of these alloys under in vitro conditions. Poly(lactic-co-glycolic acid) polymer in solution was explored at various concentrations, yielding coatings of varying thicknesses on the alloy substrates. Electrochemical corrosion studies indicate that the coatings initially provide some corrosion protection. Degradation studies showed reduced degradation over 3 days, but beyond this time point however, do not maintain a reduction in corrosion rate. Scanning electron microscopy indicates inhomogeneous coating durability, with gas pocket formation in the polymer coating, resulting in eventual detachment from the alloy surface. In vitro studies of cell viability utilizing mouse osteoblast cells showed improved biocompatibility of polymer coated substrates over the bare AZ31 and Mg4Y substrates. Results demonstrate that while challenges remain for long term degradation control, the developed polymeric coatings nevertheless provide short term corrosion protection and improved biocompatibility of magnesium alloys for possible use in orthopedic applications. PMID:23053803

  18. Bonding in MgSi and AlMgSi Compounds Relevant to AlMgSi Alloys

    OpenAIRE

    Froseth, A. G.; Derlet, P. M.; Andersen, S.J.; Marioara, C. D.; Holmestad, R.

    2003-01-01

    The bonding and stability of MgSi and AlMgSi compounds relevant to AlMgSi alloys is investigated with the use of (L)APW+(lo) DFT calculations. We show that the $\\beta$ and $\\beta''$ phases found in the precipitation sequence are characterised by the presence of covalent bonds between Si-Si nearest neighbour pairs and covalent/ionic bonds between Mg-Si nearest neighbour pairs. We then investigate the stability of two recently discovered precipitate phases, U1 and U2, both containing Al in addi...

  19. Microstructure and tensile properties of magnesium alloy modified by Si/Ca based refiner

    Institute of Scientific and Technical Information of China (English)

    DUAN Zhi-chao; SUN Yang-shan; WEI Yu; DU Wen-wen; XUE Feng; ZHU Tian-bai

    2005-01-01

    Microstructure and mechanical properties of pure magnesium and AZ31 alloy with Ca/Si based refiner addition were investigated. The results indicate that addition of Ca/Si based refiners to pure magnesium and AZ31 alloy results in remarkable microstructure refinement. With proper amount of refiner addition, the grain size in as cast ingots can be one order of magnitude lower than that without refiner addition. Small amount of refiner addition to AZ31 alloy increases both ultimate strength and yield strength significantly, while the ductility of the alloy with refiner addition is similar to that without refiner addition. Addition of refiner improves the deformability of AZ31 alloy and extruded or hot rolled specimens (rods or sheets) with refiner addition exhibit higher surface quality and mechanical properties than those without refiner addition.

  20. Electrochemical behavior of magnesium alloys as biodegradable materials in Hank's solution

    Energy Technology Data Exchange (ETDEWEB)

    Ghoneim, A.A., E-mail: Azzaghoneim@gmail.co [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt); Fekry, A.M.; Ameer, M.A. [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt)

    2010-08-01

    The electrochemical behavior of extruded AZ31E and AZ91E alloys was investigated in Hank's solution at 37 {sup o}C. The behavior of the two alloys was studied with immersion time using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss tests. It was found that the corrosion resistance of AZ31E alloy is higher than that of AZ91E. Also, the effect of adding different concentrations of a commercial drug called glucosamine sulphate (as inhibitor) to Hank's solution was studied for AZ31E alloy. The corrosion was effectively inhibited by the addition of 0.01 mM glucosamine sulphate that reacts with AZ31E alloy and forms a protective film on its surface. The results were confirmed by surface examination via scanning electron microscope.

  1. Microstructure and room temperature tensile properties of 1 μm-SiCp/AZ31B magnesium matrix composite

    Directory of Open Access Journals (Sweden)

    M.J. Shen

    2015-06-01

    Full Text Available In the present study, AZ31B magnesium matrix composites reinforced with two volume fractions (3 and 5 vol.% of micron-SiC particles(1 μm were fabricated by semisolid stirring assisted ultrasonic vibration method. The as-cast ingots were extruded at 350 °C with the extrusion ratio of 15:1 at a constant ram speed of 15 mm/s. The microstructure of the composites was investigated by optical microscopy, scanning electron microscope and transmission electron microscope. Microstructure characterization of the composites showed relative uniform reinforcement distribution and significant grain refinement. The presence of 1 μm-SiC particles assisted in improving the elastic modulus and tensile strength. The ultimate tensile strength and yield strength of the 5 vol.% SiCp/AZ31B composites were simultaneously improved.

  2. In-situ white beam microdiffraction study of the deformation behavior in polycrystalline magnesium alloy during uniaxial loading

    OpenAIRE

    Lynch, P. A.; Advanced Light Source

    2008-01-01

    Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situ measurements a light weight (~;;0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect d...

  3. Process optimization diagram based on FEM simulation for extrusion of AZ31 profile

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ram speed and the billet temperature are the primary process variables that determine the quality of the extruded magnesium profile and the productivity of the extrusion operation.The optimization of the extrusion process concerns the interplay between these two variables in relation to the extrudate temperature and the peak extrusion pressure The 3D computer simulations were performed to determine the eriects of the ram speed and the billet temperature on the extrudate temperature and the peak extrusion pressure,thereby providing guidelines for the process optimization and minimizing the number of trial extrusion runs needed for the process optimization.A case study on the extrusion of an AZ31 X-shaped profile was conducted.The correlations between the process variables and the response from the deformed material,extrudate temperature and peak extrusion pressure,were established from the 3D FEM simulations and verified by the experiment.The research opens up a way to rational selection of the process variables for ensured quality and maximum productivity of the magnesium extrusion.

  4. Dissimilar ultrasonic spot welding of Mg-Al and Mg-high strength low alloy steel

    Directory of Open Access Journals (Sweden)

    V.K. Patel

    2014-01-01

    Full Text Available Sound dissimilar lap joints were achieved via ultrasonic spot welding (USW, which is a solid-state joining technique. The addition of Sn interlayer during USW effectively blocked the formation of brittle al12Mg17 intermetallic compound in the Mg-Al dissimilar joints without interlayer, and led to the presence of a distinctive composite-like Sn and Mg2Sn eutectic structure in both Mg-Al and Mg-high strength low alloy (HSLA steel joints. The lap shear strength of both types of dissimilar joints with a Sn interlayer was significantly higher than that of the corresponding dissimilar joints without interlayer. Failure during the tensile lap shear tests occurred mainly in the mode of cohesive failure in the Mg-Al dissimilar joints and in the mode of partial cohesive failure and partial nugget pull-out in the Mg-HSLA steel dissimilar joints.

  5. Modeling of severe deformation and mechanical properties in Mg-3A1-1Zn alloy through asymmetric hot-extrusion

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    One-pass asymmetric hot extrusion performed at 673 K was applied to fabricate an AZ31 magnesium alloy sheet.Finite element method(FEM)was used to model the process of asymmetric hot-extrusion.Simulation results indicate that strain rate gradient througa the thickness introduced a grain size gradient along the thickness direction and shear deformation during the asymmetric hot-extrusion results in weakened and tilted(0002)basal texture.The asymmetric hot extrusion effectively weakens the basal texture and improves the ductility,at room temperature.

  6. Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

    Directory of Open Access Journals (Sweden)

    Chen Dongfeng

    2010-02-01

    Full Text Available AZ91D surface alloying was investigated through evaporative pattern casting (EPC technology. Aluminum powder (0.074 to 0.104 mm was used as the alloying element in the experiment. An alloying coating with excellent properties was fabricated, which mainly consisted of adhesive, co-solvent, suspending agent and other ingredients according to desired proportion. Mg-alloy melt was poured under certain temperature and the degree of negative pressure. The microstructure of the surface layer was examined by means of scanning electron microscopy. It has been found that a large volume fraction of network new phases were formed on the Mg-alloy surface, the thickness of the alloying surface layer increased with the alloying coating increasing from 0.3 mm to 0.5 mm, and the microstructure became compact. Energy dispersive X-ray (EDX analysis was used to determine the chemical composition of the new phases. It showed that the new phases mainly consist of β-Mg17Al12, in addition to a small quantity of inter-metallic compounds and oxides. A micro-hardness test and a corrosion experiment to simulate the effect of sea water were performed. The result indicated that the highest micro-hardness of the surface reaches three times that of the matrix. The corrosion rate of alloying samples declines to about a fifth of that of the as-cast AZ91D specimen.

  7. Cube phase in excess-Mg Al-Mg-Si alloy studied by EFTEM

    Czech Academy of Sciences Publication Activity Database

    Matsuda, K.; Ishida, Y.; Müllerová, Ilona; Frank, Luděk; Ikeno, S.

    Nagoya : Nagoya University, 2005. [International Symposium on Characterization of Real Materials and Real Processing by Transmission Electron Microscopy. 26.01.2005-27.01.2005, Nagoya] Institutional research plan: CEZ:AV0Z20650511 Keywords : Al-Mg-Si alloys * cube-shaped phase Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  8. Property Criteria for Automotive Al-Mg-Si Sheet Alloys

    OpenAIRE

    Ramona Prillhofer; Gunther Rank; Josef Berneder; Helmut Antrekowitsch; Uggowitzer, Peter J.; Stefan Pogatscher

    2014-01-01

    In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deplo...

  9. A Computational Investigation of Precipitates in Mg-RE Alloys With Applications To Mg-X Systems

    Science.gov (United States)

    Issa, Ahmed

    Increasing fuel efficiency in transportation vehicles is a major policy goal for both government and auto and aerospace manufacturers. Lightweight structural materials, such as magnesium alloys, hold great promise in enabling such fuel efficiency gains. Understanding the controlling factors in Mg alloy strengthening is crucial for the rational design of structurally strong and inexpensive Mg alloys. In this work, we seek to understand the energetic underpinnings giving rise to a class of remarkably strong Mg alloys: Mg-RE systems. We use first-principles methods to efficiently explore seventeen Mg-RE systems, drawing out broad patterns and distilling our knowledge into simple design rules for Mg alloys. We begin by investigating the controlling factors for the Mg-strengthening prismatic plate precipitates in Mg-RE systems, discovering the critical role of strain in such systems. We then proceed to investigate the surprising role of interfacial energies in determining the course of the Mg-RE precipitation reactions. Using strain and interfacial energies, we construct a phase-field model which accurately depicts the precipitate morphology as a function of time and size in a Mg-Nd system. Finally, we combine our gained insights to implement a computational alloy design scheme on a large portion of the periodic table where we seek Mg-strengthening solutes. Our work advances the understanding of strengthening in Mg alloys and lays the groundwork for full scale computational alloy design.

  10. In vitro responses of bone-forming MC3T3-E1 pre-osteoblasts to biodegradable Mg-based bulk metallic glasses.

    Science.gov (United States)

    Li, Haifei; He, Wei; Pang, Shujie; Liaw, Peter K; Zhang, Tao

    2016-11-01

    In light of the superior property profile of favorable biocompatibility, proper corrosion/degradation behavior and good mechanical properties, Mg-based bulk metallic glasses (BMGs) are considered as potential biodegradable biomaterials. In the present study, in vitro responses of bone-forming MC3T3-E1 pre-osteoblasts to Mg-Zn-Ca-Sr BMGs were studied in order to assess their feasibility to serve as orthopedic implants. The Mg-Zn-Ca-Sr BMGs were much more capable of supporting cell adhesion and spreading in comparison with crystalline AZ31B Mg alloy. The Mg-Zn-Ca-Sr BMG extracts showed no cytotoxicity to and slightly stimulated the proliferation of pre-osteoblasts. The cells cultured in 100% BMG extracts exhibited lower alkaline phosphatase activity as compared with that in negative control, which could be mainly ascribed to the inhibition of high concentrations of Zn ions on cell differentiation. With decreasing the extract concentration, the inhibitory effect was diminished and the 5% BMG extract exhibited slight stimulation in cell differentiation and mineralization. The high corrosion resistance of BMGs contributed to smaller environmental variations, compared with AZ31B alloy, thus lowering the unfavorable influences on cellular responses. A comparison among the biodegradable Mg-, Ca- and Sr-based BMGs for their biomedical applications is presented. PMID:27524063

  11. Micro-arc oxidation coatings on Mg-Li alloys

    Institute of Scientific and Technical Information of China (English)

    XU Yongjun; LI Kang; YAO Zhongping; JIANG Zhaohua; ZHANG Milin

    2009-01-01

    Micro-arc oxidation (MAO) method was used for the surface modification of an Mg-5wt.%Li alloy. Ceramic coatings were in-situ fabricated on the Mg-Li alloy. The morphology feature, phase composition, and corrosion-resistance of the formed ceramic coatings were studied by SEM, XRD, and electrochemical methods, respectively. The results showed that the coatings produced in a sodium silicate solution system were composed of MgO and Mg2SiO4. The ceramic coating became thicker and the content of Mg2SiO4 phase increased as the concentration of Na2SiO3 increased in the solution. The coating was loose at the low concentration of Na2SiO3 and was compact at the high concentration of Na2SiO3. The coated samples had a better corrosion resistance than the Mg-Li substrate in terms of the Tafel polarization curves and the cyclic voltammetry curves (CV).

  12. Growth restriction factor in Al-Si-Mg-Cu alloys

    International Nuclear Information System (INIS)

    The Growth Restriction Factor, Q, proved to be useful to analyse and control grain refinement during solidification of alloys. It is known that in multicomponent alloys a simple summation of the Qi values of the individual constituents taken from the binary phase diagrams can lead to grossly wrong results and that the ternary or higher-level phase diagram needs to be evaluated. This work demonstrates that the actual evaluation of Q using the liquidus gradient and partition coefficients of the multicomponent phase diagram requires some precautions and may be cumbersome. More importantly, this approach entirely fails if an intermetallic phase turns out to be the primary solidifying phase even in tiny amount. A very simple and general solution of this problem is illustrated for Al-Si-Mg-Cu alloys.

  13. Damping Evolution During Precipitation in Al-Mg-Si Alloys

    OpenAIRE

    Xie, C; Schaller, R.; Benoit, W.; Jaquerod, C.

    1996-01-01

    Damping capacity and shear elastic modulus measurements have been carried out during precipitation in AlMgSi alloys. After the specimen has been aged at the temperature corresponding to the lowest thermoelectric power, both damping and elastic modulus increase comparing with the as-quenched state. The effect of strain amplitude was investigated in specimens aged at different temperatures. A critical strain amplitude, εc, has been observed. For strain amplitudes higher than εc, the damping cap...

  14. Obtention of Al-Mg alloys of porous morphology

    International Nuclear Information System (INIS)

    With the objective of using it as fuel cell, a Mg25AI alloy of porous morphology was obtained. The material it was hydrogenates at 200 C by different time. It was analyzed by Scanning Electron Microscopy SEM and X-ray diffraction, XRD. Those XRD diffractographs present peaks run toward the origin, that which indicates a volume increase of the unitary cell by effect of the hydrogen absorption. (Author)

  15. Formation of (111) recrystallization texture in Al-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kamijo, T. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.; Iwasaki, Y. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.; Fukutomi, H. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.

    1996-09-01

    Al-4.0Mg and Al-5.5Mg alloys were warm-rolled to 85% at the temperatures ranging from 523 K to 573 K. The (001)[110] shear texture was formed in the surface of the sheets rolled below 543 K. The (111)[ anti 110] or the (112)[ anti 110] shear texture with the spread around the rolling direction developed in the sheets rolled above 553 K. After annealing the complicated recrystallization texture containing the (111) component parallel to the rolling plane was generated in the sheets rolled above 553 K. Such recrystallization texture was penetrated deeper into the inward layer with an increase in rolling temperature. (orig.)

  16. LOCAL ORDER IN THE EUTECTIC Mg.72 Zn.28 ALLOY

    OpenAIRE

    Andonov, P.; Chieux, P.

    1985-01-01

    The total structure factors S(Q) and the total pair correlation functions G(R) of the amorphous alloy Mg.72Zn.28 have been investigated by X-ray and neutron diffraction. The chemical short range order is discussed in the Bhatia-Thornton formalism and the partial coordination numbers are extracted. Comparison with the structure of crystalline Mg51Zn20 shows a weak difference in the local order due to a preference for like type atoms at the first inter-atomic distances in the disordered phase. ...

  17. Characteristics of Mg-Al-Zn alloys after laser treatment

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2008-12-01

    Full Text Available Purpose: The structure and the properties of casting magnesium alloy EN-MCMgAl3Zn1, EN-MCMgAl6Zn1,EN-MCMgAl9Zn1 and EN-MCMgAl12Zn1 after laser surface treatment are presented in this paper. The aim ofthis work was to improve the surface layer cast magnesium Mg-Al-Zn by melting and feeding of TiC particle onthe surface. The purpose of this work was to determine the laser treatment parameter.Design/methodology/approach: The experiments were performed using high power diode laser. The laser treatmentof an EN-MCMgAl3Zn1, EN-MCMgAl6Zn1, EN-MCMgAl9Zn1, EN-MCMgAl12Zn1 magnesium alloy with alloyingTiC powders was carried out using a high power diode laser (HPDL. The resulting microstructure in the modified surfacelayer was examinated using scanning electron microscopy. Phase composition was determined by the X-ray diffractionmethod using the XPert device. The measurements of hardness of the modified surface layer was also studied.Findings: The alloyed region has a fine microstructure with hard carbide particles. Hardness of laser surfacealloyed layer with TiC particles was significantly improved as compared to alloy without laser treatment forEN-MCMgAl3Zn1 and EN-MCMgAl6Zn1 alloys.Research limitations/implications: In this research one powder - TiC was used with the particle size over 6 μm.This investigation presents different speed rates feed and different laser power value for four type of magnesium alloys.Practical implications: The results obtained in this investigation were promising compared to otherconventional processes. High Power Diode Laser can be used as an economical substitute of Nd:YAG and CO2 toimprove the surface magnesium alloy by feeding the carbide particles.Originality/value: The originality of this work is applying of High Power Diode Laser for alloying ofmagnesium alloy using titanium carbide.

  18. Role of Alloying Elements in the Mechanical Behaviors of An Mg-Zn-Zr-Er Alloy

    Science.gov (United States)

    Zhang, Jing; Liu, Min; Dou, Yuchen; Liu, Guobao

    2014-11-01

    The mechanical behavior of the as-extruded and heat-treated Mg-1.5Zn-0.6Zr and Mg-1.5Zn-0.6Zr-2Er alloys was investigated and correlated with microstructure evolution. Deformation mechanisms are detailed. No evidence of twinning was observed under compression in the Er-bearing alloy throughout the grain size range of ~5 to 27 μm at a strain rate of 0.001 or 1/s. The compressive yield strength followed a Hall-Petch relation with a slope of ~10.3 MPa/mm1/2. Er played a major role in the pyramidal slip that was identified as a dominant plastic deformation mechanism. The CRSS for slip system was greatly reduced and was 98 MPa in the as-extruded alloy. While it did not change the mechanical response of the Mg-1.5Zn-0.6Zr-2Er alloy, annealing was found to promote dissolution of Zn in the Mg matrix, leading to an increase in CRSS for extension twinning in the heat-treated Mg-1.5Zn-0.6Zr alloy. As a result, twinning was only observed under a higher strain rate of 1/s in compression. The CRSS for extension twinning for the heat-treated alloy with a grain size of ~28 μm was estimated to be 40 MPa, a bit lower than that for the Er-bearing alloy of the same grain size, which was 42 MPa.

  19. Combinatorial search for hydrogen storage alloys: Mg-Ni and Mg-Ni-Ti

    Energy Technology Data Exchange (ETDEWEB)

    Oelmez, Rabia; Cakmak, Guelhan; Oeztuerk, Tayfur [Dept. of Metallurgical and Materials Engineering, Middle East Technical University, 06531 Ankara (Turkey)

    2010-11-15

    A combinatorial study was carried out for hydrogen storage alloys involving processes similar to those normally used in their fabrication. The study utilized a single sample of combined elemental (or compound) powders which were milled and consolidated into a bulk form and subsequently deformed to heavy strains. The mixture was then subjected to a post annealing treatment, which brings about solid state reactions between the powders, yielding equilibrium phases in the respective alloy system. A sample, comprising the equilibrium phases, was then pulverized and screened for hydrogen storage compositions. X-ray diffraction was used as a screening tool, the sample having been examined both in the as processed and the hydrogenated state. The method was successfully applied to Mg-Ni and Mg-Ni-Ti yielding the well known Mg{sub 2}Ni as the storage composition. It is concluded that a partitioning of the alloy system into regions of similar solidus temperature would be required to encompass the full spectrum of equilibrium phases. (author)

  20. Antibacterial polyelectrolyte-coated Mg alloys for biomedical applications

    Science.gov (United States)

    Seraz, Md. S.; Asmatulu, R.; Chen, Z.; Ceylan, M.; Mahapatro, A.; Yang, S. Y.

    2014-04-01

    This study deals with two biomedical subjects: corrosion rates of polyelectrolyte-coated magnesium (Mg) alloys, mainly used for biomedical purposes, and antibacterial properties of these alloys. Thin sheets of Mg alloys were coated with cationic polyelectrolyte chitosan (CHI) and anionic polyelectrolyte carboxymethyl cellulose (CMC) using a layer-by-layer coating method and then embedded with antibacterial agents under vacuum. Electrochemical impedance spectroscopy was employed to analyze these samples in order to detect their corrosion properties at different conditions. In the electrochemical analysis section, a corrosion rate of 72 mille inches per year was found in a salt solution for the sample coated with a 12 phosphonic acid self-assembled monolayer and 9 CHI/CMC multilayers. In the antibacterial tests, gentamicin was used to investigate the effects of the drug embedded with the coated surfaces against the Escherichia coli (E. coli) bacteria. Antibacterial studies were tested using the disk diffusion method. Based on the standard diameter of the zone of inhibition chart, the antibacterial diffusion from the surface strongly inhibited bacterial growth in the regions. The largest recorded diameter of the zone of inhibition was 50 mm for the pre-UV treated and gentamicin-loaded sample, which is more than three times the standard diameter.

  1. Improvement of Corrosion Resistance of Binary Mg-Ca Alloys Using Duplex Aluminum-Chromium Coatings

    Science.gov (United States)

    Daroonparvar, Mohammadreza; Yajid, Muhamad Azizi Mat; Yusof, Noordin Mohd; Bakhsheshi-Rad, Hamid Reza; Adabi, Mohsen; Hamzah, Esah; Kamali, Hussein Ali

    2015-07-01

    Al-AlCr was coated on Mg-Ca and Mg-Zn-Ce-La alloys using physical vapor deposition method. The surface morphology of the specimens was characterized by x-ray diffraction, scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and atomic force microscopy (AFM). The AFM results indicated that the average surface roughness of Al-AlCr coating on the Mg-Ca alloy is much lower than that of Al-AlCr coating on the Mg-Zn-Ce-La alloy. However, Al-AlCr coating on the Mg-Ca alloy presented a more compact structure with fewer pores, pinholes, and cracks than Al-AlCr coating on the Mg-Zn-Ce-La alloy. Electrochemical studies revealed that the novel coating (Al-AlCr) can remarkably reduce the corrosion rate of the Mg-Ca alloy in 3.5 wt.% NaCl solution. It was seen that the anodic current density of the Al-AlCr-coated Mg-Ca alloy was very small when compared to the Al-AlCr-coated Mg-Zn-Ce-La and uncoated alloys. Impedance modulus ( Z) of the Al-AlCr-coated samples was higher than that of the bare Mg alloys. Z of Al-AlCr-coated Mg-Ca alloy was higher than that of the Al-AlCr-coated Mg-Zn-Ce-La alloy at low frequency.

  2. Numerical and experimental investigations on the warm deep drawing process of circular aluminum alloy specimens

    Directory of Open Access Journals (Sweden)

    G. Palumbo

    2005-12-01

    Full Text Available Purpose: The present work is aimed to investigate the Deep Drawing process of Mg alloy sheet in Warm conditions, since through the temperature temperature the number of independent slip systems of the Mg alloys can be enlarged.Design/methodology/approach: A FE model and an equipment for warm deep drawing tests were created, since an experimental-numerical method was adopted; the most efficient heating positioning and the most suitable way of performing the WDD process was evaluated using data coming from the numerical model and temperature and punch load acquisition coming from experimental activity.Findings: Limit Drawing Ratio (LDR equal to 2.6 for AZ31 Mg alloy (cross rolled, thickness 0.6mm was obtained at the temperature 170oC using heater embedded in the female die; Drawing Ratio equal to 3.1 for the same Mg alloy (thickness 0.6mm was obtained setting the temperature of the blank holder at 250oC (throughout heaters embedded in it and cooling the central part using a water cooled punch.Research limitations/implications: Next step of the research will be to evaluate the optimal value of process parameters (speed, temperature and blank holder pressure in order to draw the process window.Practical implications: The process with controlled heating and cooling technology can be applied in industrial production of a wide range of Mg alloy parts (structural components, covers for computer, communication and customer electronic, sportive equipments.Originality/value: Specific heating and cooling system were designed to analyse the influence of the different heating strategies combined with or without punch cooling on the WDD of AZ31 Mg alloy sheets.

  3. College of Chemistry and Chemical Engineer- ing, Chongqing University, Chongqing 400044, China%AZ31镁合金阳极氧化膜在3.5%NaCl溶液中不同浸泡时间的腐蚀机制

    Institute of Scientific and Technical Information of China (English)

    刘渝萍; 宋卫华; 陈昌国; 尹玲; 郭朝中

    2013-01-01

    A semiconductor electrochemical method was adopted to measure the polarization curveand capacity of anodic oxidation film on AZ31 Mg alloy in 3.5% NaCl solution so as to reveal the correlation between the corrosionresistance and semiconductor characteristics of the film. Thecarrier density and flat-band potential of the anodic oxidation film at different immersion time were determined. Results showed that the anodic oxidation film formed on Mg alloy surface was an N-type semiconductor, and its carrier density tended to rise with extending immersion time (it increased from 1. 83×10 cm-3 at 10 min of immersion to 8. 60×1020 cm-3 at 96 h of immersion). Besides, the anodic oxidation film had a flat - band potential of - 1.69 ~ - 1.52 V (lower than that of Mg alloy ( - 1.44 ~- 1. 57 V) ) , and the anodic oxidation film obtained at an immersion time of 1 h had the lowest flat - band potential andpossessed the best corrosion resistance. Moreover, the failure process of the anodic oxidation film could be divided into four stages, including self - repair period, induction period of pitting corrosion, pitting corrosion period and quick corrosion period.%为了进一步弄清AZ31镁合金阳极氧化膜在NaCl溶液中的腐蚀机制,采用极化曲线、电容测量技术,基于半导体电化学方法研究了其在3.5 %NaCl溶液中耐蚀性能与其半导体特性的关系,得到不同浸泡时间下的载流子浓度以及平带电位.结果表明:镁合金阳极氧化膜为N型半导体,随浸泡时间的增加,载流子浓度呈上升趋势,由浸泡10 min时的1.83×1018 cm-3增大到96 h时8.60×1020cm-3,平带电位为-1.69~-1.52V,低于镁合金(-1.44~-1.57 V),在浸泡时间为1h时膜的平带电位最负,耐蚀性最好;镁合金阳极氧化膜的腐蚀失效过程会经过自我修复期-点蚀诱导期-点蚀期-快速腐蚀期4个阶段.

  4. In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

    International Nuclear Information System (INIS)

    The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi2O6) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating

  5. Low frequency damping capacities and mechanical properties of Mg-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hu, X.S. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)], E-Mail: huxiaoshi@hit.edu.cn; Wu, K. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zheng, M.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Gan, W.M. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, X.J. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2007-04-15

    The effect of Si content on low frequency damping capacities and mechanical properties of as-cast Mg-Si alloys were investigated. Both hypoeutectic alloys with 0.3 wt.%Si, 0.8 wt.%Si and hypereutectic alloy with 2.3 wt.%Si exhibit high damping capacities since these Mg-Si alloys possess large size {alpha}-Mg phase with very small amount of soluble atoms in it. The amount of the in situ formed Mg{sub 2}Si determines the dislocation density and then influences the damping capacity of these Mg-Si alloys. The Mg-0.3 wt.%Si alloy exhibits the lowest damping value at small strain region but the highest damping value at large strain region among these Mg-Si alloys. Two damping peaks were found in Mg-Si alloys at 80 and 230 deg. C, respectively. But the addition of Al in Mg-Si alloy impeded the appearance of these two damping peaks since the soluble Al atoms hindered the movement of dislocations and the slide of grain boundaries. The presence of large size, brittle primary Mg{sub 2}Si particles decreases the tensile strength and ductility of the hypereutectic Mg-Si alloy.

  6. Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); State Key Laboratory for Turbulence and Complex System, College of Engineering, Peking University, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2013-10-15

    The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process.

  7. Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

    International Nuclear Information System (INIS)

    The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process

  8. 氯化铈对镁合金在NaCl溶液中的缓蚀作用%Inhibition Effect of Rare Earth on Magnesium Alloy in NaCl Solution

    Institute of Scientific and Technical Information of China (English)

    张云霞

    2011-01-01

    采用电化学阻抗法和动电位极化曲线法研究了氯化铈对镁合金AZ31在3.5%NaCl溶液中腐蚀行为的影响,用扫描电镜(SEM)和能谱仪(EDS)分析了腐蚀产物膜的形貌和成分.结果表明,当NaCl溶液中加入50~200mg/L氯化铈时,镁合金的腐蚀速率均有降低,当稀土含量为l00mg/L时,腐蚀速率最低;加入适当的稀土,腐蚀产物膜的均匀性和致密性较好,不存在微裂纹等缺陷;浸泡试验结果证实了稀土对镁合金的缓蚀作用.%The effect of CeCl3 on the corrosion behaviors of AZ31 Mg alloy in 3. 5% NaCl solution was investigated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The morphology and chemical composition of the corrosion products were analyzed by SEM and ED& The results showed that the corrosion rate of AZ31 Mg alloy was reduced by adding CeCl3 with concentrations of 50~200 mg/L, and the lowest corrosion rate was at the concentration of 100 mg/L. Uniformity and density of corrosion product was good, and there were no micro-cracks. The corrosion inhibition effect was confirmed by immersion experiment

  9. In vitro biocompatibility of Ti–Mg alloys fabricated by direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Ti–xMg (x = 17, 33, and 55 mass%) alloy films, which cannot be prepared by conventional melting processes owing to the absence of a solid-solution phase in the phase diagram, were prepared by direct current magnetron sputtering in order to investigate their biocompatibility. Ti and Mg films were also prepared by the same process for comparison. The crystal structures were examined by X-ray diffraction (XRD) analysis and the surfaces were analyzed by X-ray photoelectron spectroscopy. The Ti, Ti–xMg alloy, and Mg films were immersed in a 0.9% NaCl solution at 310 K for 7 d to evaluate the dissolution amounts of Ti and Mg. In addition, to evaluate the formation ability of calcium phosphate in vitro, the Ti, Ti–xMg alloy, and Mg films were immersed in Hanks' solution at 310 K for 30 d. Ti and Mg form solid-solution alloys because the peaks attributed to pure Ti and Mg do not appear in the XRD patterns of any of the Ti–xMg alloy films. The surfaces of the Ti–17Mg alloy and Ti–33Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti–55Mg alloy and Mg films. The dissolution amounts of Ti from all films are below or near the detection limit of inductively coupled plasma-optical emission spectroscopy. On the other hand, the Ti–17Mg alloy, Ti–33Mg alloy, Ti–55Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 μg/cm2, respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti–33Mg alloy, Ti–55Mg alloy, and Mg films after the immersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti–33Mg film. However, many cracks are observed in the Ti–55Mg film, and delamination of the film occurs after the immersion in Hanks' solution. The Mg film is dissolved in Hanks' solution and calcium phosphate particles precipitate on the glass substrate

  10. In vitro biocompatibility of Ti–Mg alloys fabricated by direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Hieda, Junko, E-mail: hieda@imr.tohoku.ac.jp; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken

    2015-09-01

    Ti–xMg (x = 17, 33, and 55 mass%) alloy films, which cannot be prepared by conventional melting processes owing to the absence of a solid-solution phase in the phase diagram, were prepared by direct current magnetron sputtering in order to investigate their biocompatibility. Ti and Mg films were also prepared by the same process for comparison. The crystal structures were examined by X-ray diffraction (XRD) analysis and the surfaces were analyzed by X-ray photoelectron spectroscopy. The Ti, Ti–xMg alloy, and Mg films were immersed in a 0.9% NaCl solution at 310 K for 7 d to evaluate the dissolution amounts of Ti and Mg. In addition, to evaluate the formation ability of calcium phosphate in vitro, the Ti, Ti–xMg alloy, and Mg films were immersed in Hanks' solution at 310 K for 30 d. Ti and Mg form solid-solution alloys because the peaks attributed to pure Ti and Mg do not appear in the XRD patterns of any of the Ti–xMg alloy films. The surfaces of the Ti–17Mg alloy and Ti–33Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti–55Mg alloy and Mg films. The dissolution amounts of Ti from all films are below or near the detection limit of inductively coupled plasma-optical emission spectroscopy. On the other hand, the Ti–17Mg alloy, Ti–33Mg alloy, Ti–55Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 μg/cm{sup 2}, respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti–33Mg alloy, Ti–55Mg alloy, and Mg films after the immersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti–33Mg film. However, many cracks are observed in the Ti–55Mg film, and delamination of the film occurs after the immersion in Hanks' solution. The Mg film is dissolved in Hanks' solution and calcium phosphate particles precipitate on the glass substrate

  11. Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys.

    Science.gov (United States)

    Liu, X L; Zhou, W R; Wu, Y H; Cheng, Y; Zheng, Y F

    2013-10-01

    The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg-Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. PMID:23910326

  12. High Energy Storage Mg-based amorphous alloys for nickel-metal hydride battery

    International Nuclear Information System (INIS)

    Full text: Mg-based hydrogen storage alloys possess very high hydrogen absorption capacity (For example, Mg2NiH4 contains 3.6 wt.% of hydrogen). Magnesium is also abundant in nature, light in weight and low in cost. As a result, magnesium alloys have become the subject of increasing research world-wide. For a long period, it was thought that Mg-based alloy-hydrogen systems needed to be operated at high temperature (over 250 deg C) and under high hydrogen pressure. However, in recent years, some research work was successfully done to improve the hydrogen absorption kinetics of Mg2Ni by mechanical grinding and alloying. Some nano and amorphous structured Mg2Ni alloys could absorb hydrogen even at room temperature. Our research results show that it is possible to use Mg2Ni-type alloys as promising materials for increasing the negative electrode capacity of Ni-MH batteries because the theoretical discharge capacity of Mg2Ni alloy is approximately 1000 mAh/g, much higher than that of the main commercial LaNi5 alloy (which has a capacity of only about 370 mAh/g). Mg-based alloy electrodes were manufactured by a powder metallurgical technique or a induction melting method followed by ball milling with Ni and/or other metal powders. The discharge capacities of the Mg-based alloy electrodes were significantly improved by ball milling. An amorphous structure is a key factor in order to achieve high discharge capacities. The figure below shows the ball milled amorphous Mg-based alloy electrodes have very high discharge capacities by comparison with crystalline Mg2Ni alloys or commercial AB5 alloy

  13. HREM study of disclinations in MgCd ordered alloy

    International Nuclear Information System (INIS)

    Multiple twin boundaries are investigated by HREM for the MgCd ordered alloy. Multiple intersection of twin boundaries exists in the crystal without any relaxation due to lattice dislocations. This intersection is recognized as one of the linear defects, called a disclination. The strain field around a disclination is relaxed by making one or more nearby disclinations opposite in sign. HREM investigation makes it possible not only to determine the types of the disclination but also to confirm crystals not having the lattice dislocations. A tripole-star pattern is found to be a disclination and is constructed in order to compensate for the strain energy of the disclination. Disclinations are likely to distribute to make multipoles in the crystal. (orig.)

  14. HREM study of disclinations in MgCd ordered alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kitano, Y. (Dept. of Materials Science, Hiroshima Univ., Higashi-Hiroshima (Japan)); Kifune, K. (Dept. of Natural Science, Osaka Women' s Univ. (Japan))

    1991-11-01

    Multiple twin boundaries are investigated by HREM for the MgCd ordered alloy. Multiple intersection of twin boundaries exists in the crystal without any relaxation due to lattice dislocations. This intersection is recognized as one of the linear defects, called a disclination. The strain field around a disclination is relaxed by making one or more nearby disclinations opposite in sign. HREM investigation makes it possible not only to determine the types of the disclination but also to confirm crystals not having the lattice dislocations. A tripole-star pattern is found to be a disclination and is constructed in order to compensate for the strain energy of the disclination. Disclinations are likely to distribute to make multipoles in the crystal. (orig.).

  15. Precipitation of prismatic plates in Mg-0.3Ca alloys with In additions

    International Nuclear Information System (INIS)

    In Mg alloys, prismatic plates are predicted to be more effective for age hardening compared with the basal plates that are commonly observed in Mg-rare earth (RE) or Mg-Ca alloys with Zn. This study reports that a high number density of thin prismatic plates can be precipitated in Mg-0.3Ca alloy by microalloying with In, resulting in an enhanced age-hardening response three times higher than that for the binary alloy. The precipitates are composed of three {1 0 1-bar 0} prismatic planes enriched with Ca and In.

  16. Microstructure and properties of new Mg-Li-Zn wrought alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Cold-rolling workability, heat treatment characteristics and mechanical properties of Mg-5%-22 % Li-2 % Zn(mass fraction) wrought alloys were studied. Density of alloys is between 1.19 and 1.62 g/cm3. The limit of reduction for cold rolling of the β phase alloys at 16% and 22%Li exceeds 90% at room temperature. The properties and microstructures of Mg-Li-Zn alloys were studied, which were homogenized, cold rolled, then annealed at different temperatures. Recrystallization behaviors of the alloys were investigated through microstructures observing and hardness measuring. The results show that the cast billets are suitable for rolling after homogenization at 573K for 12 h for Mg-9Li-2Zn-2Ca alloy and at 523K for 24 h for Mg-9Li-2Zn-2Ca alloy. The cold rolled plates were completely recrystallizated by annealing at 573K for 1 h.

  17. Electrochemical formation process and phase control of Mg-Li-Ce alloys in molten chlorides

    Institute of Scientific and Technical Information of China (English)

    ZHANG Meng; HAN Wei; ZHANG Milin; ZHU Fengyan; XUE Yun; ZHANG Zhijian

    2013-01-01

    An electrochemical approach for the preparation of Mg-Li-Ce alloys by co-reduction of Mg,Li and Ce on a molybdenum electrode in KCl-LiCl-MgCl2-CeCl3 melts at 873 K was investigated.Cyclic voltammograms (CVs) and square wave voltammograms indicated that the underpotential deposition (UPD) of cerium on pre-deposited magnesium led to the formation of Mg-Ce alloys at electrode potentials around-1.87 V.The order of electrode reactions was as follows:discharge of Mg(Ⅱ) to Mg-metal,UPD of Ce on the surface of pre-deposited Mg with formation of Mg-Ce alloys,discharge of Ce(Ⅲ) to Ce-metal and after that the discharge of Li+ with the deposition of Mg-Li-Ce alloys,which was investigated by CVs,chronoamperometry,chronopotentiometry and open circuit chronopotentiometry.X-ray diffraction (XRD) illuminated that Mg-Li-Ce alloys with different phases were obtained via galvanostatic electrolysis by different current densities.The microstructures of Mg-Li-Ce alloys were characterized by optical microscopy (OM) and scanning electron microscopy (SEM),respectively.The analysis of energy dispersive spectrometry (EDS) showed that Ce existed at grain boundaries to restrain the grain growth.The compositions and the average grain sizes of Mg-Li-Ce alloys could be obtained controllably corresponding with the phase structures of the XRD patterns.

  18. Microstructure, cold rolling, heat treatment, and mechanical properties of Mg-Li alloys

    Institute of Scientific and Technical Information of China (English)

    Haibin Ji; Guangchun Yao; Hongbin Li

    2008-01-01

    The magnesium-lithium (Mg-Li) alloy exhibits two phase structures between 5.7wt% and 10.3wt% Li contents, consisting of the a (hcp) Mg-rich and the β (bee) Li-rich phases, at room temperature. In the experiment, Mg-5Li-2Zn, Mg-9Li-2Zn,Mg-16Li-2Zn, Mg-22Li-2Zn, Mg-5Li-2Zn-2Ca, Mg-9Li-2Zn-2Ca, Mg-16Li-2Zn-2Ca, and Mg-22Li-2Zn-2Ca (wt%) were melted.During the melting process, the flux, which was composed of lithium chloride (LiCI) and lithium fluoride (LiF) in the proportion of 3:1 (mass ratio) and argon gas were used to protect the alloys from oxidation. The mierostructure, mechanical properties, and cold-rolling workability of the wrought alloys were studied. The crystal grain of the alloys (adding Ga) is fine. The hardness of the studied alloys decreases with an increase in element Li. The density of the studied alloys is in the range of 1.187 to 1.617 g/cm3 The reduction of the Mg-16Li-2Zn and Mg-22Li-2Zn alloys can exceed 85% at room temperature. The Mg-9Li-2Zn-2Ca alloy was heat treated at 300℃ for 8, 12, 16, and 24 h, respectively. The optimum heat treatment of the Mg-9Li-2Zn-2Ca alloy is 300~Cx12h by metallographic observation and by studying the mechanical properties of the alloys.

  19. As-cast microstructure of Al-Zn-Mg and Al-Zn-Mg-Cu alloys added erbium

    Institute of Scientific and Technical Information of China (English)

    MAO Jian-wei; JIN Tou-nan; XU Guo-fu; NIE Zuo-ren

    2005-01-01

    The effects of different contents of rare earth element, and erbium, on the as-cast microstructures of Al-6Zn-2Mg and Al-6Zn-2Mg-1.8Cu alloys were studied by optical microscopy, scanning electron microscopy, X-ray diffractometry, transmission electron microscopy and EDS analysis. The results show that the netlike structure of as-cast alloys can be remarkably refined, and the distance of dendritic structure decreases, with Er addition. However, the improvement results on Al-Zn-Mg-Cu are not better than that of Al-Zn-Mg. Er and Al can interact to form Al3Er phase, which is coherent with α(Al) matrix, with trace Er addition to the Al-Zn-Mg alloy. The refinement effect of Al-Zn-Mg alloys is familiar with the formation and precipitation of coherent Al3Er phases. The ternary compound AlCuEr, similar with AlCuSc phase, will form when Er is added to Al-Zn-Mg-Cu alloy, which suppresses the formation of Al3Er phase and doesn't solve in the following heat treatment.

  20. The effects of Mg amount on the microstructure and mechanical properties of Al–Si–Mg alloys

    International Nuclear Information System (INIS)

    Highlights: • Mg effects on microstructure and mechanical properties of Al–Si–Mg were studied. • Three alloys with different amounts were cast, homogenized and exposed to T6. • Intermetallic compounds were formed on the microstructure by increasing Mg amount. • Hardness and tensile strength increased with increasing Mg content. • Elongation and density decreased with increasing Mg content. - Abstract: In this study, the effects of magnesium (Mg) addition to A356 aluminum alloy at different amounts on the microstructure and mechanical properties of this alloy were examined. For the experimental studies, three different alloys (0.43, 0.67 and 0.86 wt%) having various amounts of Mg were prepared through casting process in the form of plates. The plates were homogenized and cooled in the furnace. All the samples were treated with aging process (T6) and then tensile samples were prepared from the homogenized samples. The samples treated with T6 process were characterized by optical microscopy, laser confocal microscopy, Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-Ray Diffraction (XRD) examinations as well as hardness measurements and tensile tests. The phases which were formed in the microstructures for different amounts of Mg were examined. It was observed that iron-rich intermetallic compounds were also formed in addition to the phases resulting from the aging process. Fe-rich intermetallic compounds, observed from the fracture surfaces, were found to reduce the tensile strength the alloy. The results also indicate that the tensile strength and hardness of the alloy increase with increasing Mg amount

  1. Geometric and Chemical Composition Effects on Healing Kinetics of Voids in Mg-bearing Al Alloys

    Science.gov (United States)

    Song, Miao; Du, Kui; Wang, Chunyang; Wen, Shengping; Huang, Hui; Nie, Zuoren; Ye, Hengqiang

    2016-05-01

    The healing kinetics of nanometer-scale voids in Al-Mg-Er and Al-Mg-Zn-Er alloy systems were investigated with a combination of in situ transmission electron microscopy and electron tomography at different temperatures. Mg was observed completely healing the voids, which were then rejuvenated to the alloy composition with further aging, in the Al-Mg-Er alloy. On the contrary, Mg51Zn20 intermetallic compound was formed in voids in the Al-Mg-Zn-Er alloy, which leads to complete filling of the voids but not rejuvenation for the material. For voids with different geometrical aspects, different evolution processes were observed, which are related to the competition between bulk and surface diffusion of the alloys. For voids with a large size difference in their two ends, a viscous flow of surface atoms can be directly observed with in situ electron microscopy, when the size of one end becomes less than tens of nanometers.

  2. Laser cladding of a Mg based Mg-Gd-Y-Zr alloy with Al-Si powders

    Science.gov (United States)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-03-01

    In the present work, a Mg based Mg-Gd-Y-Zr alloy was subjected to laser cladding with Al-Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg2Si, Mg17Al12 and Al2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg2Si, Mg17Al12 and Al2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from -1.77 V for the untreated alloy to -1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10-5 A cm-2 to 1.64 × 10-6 A cm-2. The results show that laser cladding is an efficient method to improve surface properties of Mg-Rare earth alloys.

  3. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Department of Dentistry, Chang Yin dental clinic, No.46-1, Yangming St., Banqiao City, Taipei County 220, Taiwan (China); Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Chen, May-Show [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Lin, Ling-Hung [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Wu, Ching-Zong, E-mail: chinaowu@tmu.edu.tw [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Ou, Keng-Liang, E-mail: klou@tmu.edu.tw [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Graduated Institute of Biomedical Materials and Engineering, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Yu, Chih-Hua [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China)

    2011-01-21

    Research highlights: > When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). > As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. > The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  4. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    International Nuclear Information System (INIS)

    Research highlights: → When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be α-Mg → (α-Mg + twindense) → (α-Mg + twinloose) → (α-Mg + α-Zr). → As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. → The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: α-Mg → (α-Mg + twindense) → (α-Mg + twinloose) → (α-Mg + α-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  5. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg) alloys

    OpenAIRE

    M. Kaczorowski; A. Krzyńska

    2007-01-01

    The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg) type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening ...

  6. Studies of corrosion behaviour in alkaline environment of binary Mg-Li alloys for plastic forming

    OpenAIRE

    M. Żmudzińska; A. Białobrzeski; K. Saja

    2011-01-01

    The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an alkaline medium (5% NaClsolution) for the time of 0-144 hours. In short it can be stated that the increase of Li content in magnesium alloys from 3% to 9% increasesthe corrosion resistance of alloy (the lowest susceptibility to corrosion in NaCl solution showed Mg- Li9 alloy). Increasing the content ofLi in alloy to over 9% resulted in a significant increase of the susceptibility to cor...

  7. Studies of corrosion behaviour in alkaline environment of binary Mg-Li alloys for plastic forming

    Directory of Open Access Journals (Sweden)

    M. Żmudzińska

    2011-07-01

    Full Text Available The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an alkaline medium (5% NaClsolution for the time of 0-144 hours. In short it can be stated that the increase of Li content in magnesium alloys from 3% to 9% increasesthe corrosion resistance of alloy (the lowest susceptibility to corrosion in NaCl solution showed Mg- Li9 alloy. Increasing the content ofLi in alloy to over 9% resulted in a significant increase of the susceptibility to corrosion.

  8. The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

    Science.gov (United States)

    Gilman, P. S.

    1984-01-01

    Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

  9. The synthesis and characterization of Mg-Zn-Ca alloy by powder metallurgy process

    Science.gov (United States)

    Annur, Dhyah; Franciska P., L.; Erryani, Aprilia; Amal, M. Ikhlasul; Sitorus, Lyandra S.; Kartika, Ika

    2016-04-01

    Known for its biodegradation and biocompatible properties, magnesium alloys have gained many interests to be researched as implant material. In this study, Mg-3Zn-1Ca, Mg-29Zn-1Ca, and Mg-53Zn-4.3Ca (in wt%) were synthesized by means of powder metallurgy method. The compression strength and corrosion resistance of magnesium alloy were thoroughly examined. The microstructures of the alloy were characterized using optical microscopy, Scanning Electron Microscope, and also X-ray diffraction analysis. The corrosion resistance were evaluated using electrochemical analysis. The result indicated that Mg- Zn- Ca alloy could be synthesized using powder metallurgy method. This study showed that Mg-29Zn-1Ca would make the highest mechanical strength up to 159.81 MPa. Strengthening mechanism can be explained by precipitation hardening and grain refinement mechanism. Phase analysis had shown the formation of α Mg, MgO, and intermetallic phases: Mg2Zn11 and also Ca2Mg6Zn3. However, when the composition of Zn reach 53% weight, the mechanical strength will be decreasing. In addition, all of Mg-Zn-Ca alloy studied here had better corrosion resistance (Ecorr around -1.4 VSCE) than previous study of Mg. This study indicated that Mg- 29Zn- 1Ca alloy can be further analyzed to be a biodegradable implant material.

  10. Preparation of Mg-Li alloys by electrolysis in molten salt at low temperature

    Institute of Scientific and Technical Information of China (English)

    Mi Lin Zhang; Yong De Yan; Zhi Yao Hou; Lu An Fan; Zeng Chen; Ding Xiang Tang

    2007-01-01

    A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.

  11. Design of an age hardening Mg-Li alloy and its aging behavior

    Institute of Scientific and Technical Information of China (English)

    Hao Zhong; Peiying Liu; Tietao Zhou; Huanxi Li

    2005-01-01

    An effort was made to design an age hardening Mg-Li alloy based on the phase diagrams calculated by means of "THERMO-CALC"-a thermodynamic software. Experiments were carried out to verify the calculated results by melting the alloy and examining its structure and aging behavior. The results show that the alloy possesses a structure constituent as expected, besides,the alloy has apparent aging behavior and over aging happens even at lower temperature. Metastable (Mg, Li, Al, Zn) phase has been identified when the hardness reaches the aging peak. With the increase of the aging time, (Mg, Li, Al, Zn) phase transforms to stable α phase and over aging happens.

  12. Application of silicocalcium in Mg-6Al-0.5Mn alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The mechanical properties of magnesium alloys at both ambient and elevated temperatures can be improved with the existence of Mg2Si phase in the matrix. However, these properties can be deteriorated if the Mg2Si phase is of coarse Chinese script type. Effects of the silicocalcium addition on the microstructure and properties of an Mg-6Al-0.5Mn alloy (AM60) were studied. The microstructure of the alloy with the addition of silicocalcium is featured with dispersedly distributed small polygonal type Mg2Si phases. The microhardness, tensile strength,percentage elongation and toughness of as-cast AM60+1.0Si-Ca alloy are 20%, 13.3%, 28.5% and 50% higher than these of AM60 alloy respectively. Further corrosion measurements showed that the silicocalcium-modified AM60 alloy increases the corrosion potential by 0.04V and decreases the lost weight corrosion rate by 45%.

  13. Effect of Mg on microstructures and properties of Al-Mg-Si-Cu aluminium alloys for automotive body sheets

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; SONG Wen-ju; ZHAO Gang; LIU Chun-ming; ZUO Liang

    2005-01-01

    The effects of variation of Mg content on microstructures,the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy,optical metallographic analysis,tensile and Ericsson tests.The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si,with an increment of Mg content,the strength enhances,the specific elongation and Erisson values of alloys decrease,and the number of Mg2 Si constituent increases and that of Al(MnFe)Si type constituents reduces.Al-MgSi-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint bake cycle (I.e.artificial aging at 170 ℃ for 30 min immediately after the solution treatment and quenching).Suitable Mg content should be controlled in the range of 0.8% and 1.2 % (mass fraction).

  14. Corrosion and Discharge Behaviors of Mg-Al-Zn and Mg-Al-Zn-In Alloys as Anode Materials

    Directory of Open Access Journals (Sweden)

    Jiarun Li

    2016-03-01

    Full Text Available The Mg-6%Al-3%Zn and Mg-6%Al-3%Zn-(1%, 1.5%, 2%In alloys were prepared by melting and casting. Their microstructures were investigated via metallographic and energy-dispersive X-ray spectroscopy (EDS analysis. Moreover, hydrogen evolution and electrochemical tests were carried out in 3.5 wt% NaCl solution aiming at identifying their corrosion mechanisms and discharge behaviors. The results suggested that indium exerts an improvement on both the corrosion rate and the discharge activity of Mg-Al-Zn alloy via the effects of grain refining, β-Mg17Al12 precipitation, dissolving-reprecipitation, and self-peeling. The Mg-6%Al-3%Zn-1.5%In alloy with the highest corrosion rate at free corrosion potential did not perform desirable discharge activity indicating that the barrier effect caused by the β-Mg17Al12 phase would have been enhanced under the conditions of anodic polarization. The Mg-6%Al-3%Zn-1.0%In alloy with a relative low corrosion rate and a high discharge activity is a promising anode material for both cathodic protection and chemical power source applications.

  15. In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

    Energy Technology Data Exchange (ETDEWEB)

    Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

    2014-08-01

    The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi{sub 2}O{sub 6}) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating.

  16. Studies of corrosion behaviour in acid environment of binary Mg-Li alloys for plastic forming

    Directory of Open Access Journals (Sweden)

    A. Białobrzeski

    2011-07-01

    Full Text Available The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an acid medium (5% HCl solutionfor the time of 0-144 hours. In short it can be stated that corrosion of the examined Mg-Li alloys in 5% HCl solution proceeded in a similarmode in all the studied alloys, regardless of the lithium content.

  17. Studies of corrosion behaviour in acid environment of binary Mg-Li alloys for plastic forming

    OpenAIRE

    A. Białobrzeski; K. Saja; M. Żmudzińska

    2011-01-01

    The article discusses studies and corrosion tests of binary Mg-Li alloys for plastic forming examined in an acid medium (5% HCl solution)for the time of 0-144 hours. In short it can be stated that corrosion of the examined Mg-Li alloys in 5% HCl solution proceeded in a similarmode in all the studied alloys, regardless of the lithium content.

  18. Phase diagrams of aluminium alloys of Al-Cu-Mg, Al-Mg-Si-Cu, and Al-Mg-Li system

    International Nuclear Information System (INIS)

    Isothermal diagrams of phase transformations (DPT) and temperature-time charts (TTC) of variation of electric conductivity and of mechanical features at tension were plotted following thermal treatment according to the pattern of direct hardening and ageing and according to the pattern of normal aging for D16 commercial alloy, Al-Cu-Mg model alloy of the same system, AD37 commercial alloys of Al-Mg-Si-Cu and 1424 one of Al-Li-Mg system. Phase transformations were studied by means of fluorescence electron microscopy, micro-X-ray spectral analysis, X-ray phase analysis of single crystals and polycrystals and differential scanning calorimetry. For every alloy comparison of TTC and DPT enables to clarity the mechanism of phase composition effect on features and to optimize conditions of hardening cooling and ageing

  19. Rietveld analysis of neutron powder diffraction of Mg6Pd alloy at various hydriding stages

    International Nuclear Information System (INIS)

    The evolution of the crystal structure of Mg6Pd alloy, synthesized by ball milling, was investigated by simultaneous Rietveld refinement of neutron and X-ray powder diffraction. Samples with different deuterium contents were measured, corresponding to reaction end-products of proposed hydrogenation step. After full hydrogenation, Mg6Pd alloy transforms to MgPd alloy and MgD2. Increases in lattice parameters of MgPd alloy agrees well with measured hydrogen capacities. There are some evidences that at each hydrogenation step in magnesium alloys, magnesium atoms with high values of thermal parameters are the ones that will form magnesium hydride upon hydrogenation. Magnesium hydride phases presented a high level of strain which could be related to the important hysteresis in the pressure-composition isotherm curve.

  20. Mechanical properties, in vitro corrosion and biocompatibility of newly developed biodegradable Mg-Zr-Sr-Ho alloys for biomedical applications.

    Science.gov (United States)

    Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

    2016-01-01

    Our previous studies have demonstrated that Mg-Zr-Sr alloys can be anticipated as excellent biodegradable implant materials for load-bearing applications. In general, rare earth elements (REEs) are widely used in magnesium (Mg) alloys with the aim of enhancing the