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Sample records for az31 mg alloy

  1. Isothermal Gas Forming of Mg Alloy AZ31 Sheet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There have been reports on sheet forming of Mg alloy in industry via the punch and die method; this paper is probably the first formal one for studying the sheet formability of AZ31 employing pressurized gas to press the sheet into a female die cavity at various elevated temperatures. The results indicate it is feasible to form a rectangular box via pressurized gas from extruded sheets of 0.5 and 1.7 mm thick. The formed box has 1:2 depth over width ratio,which should be large enough when dealing with realistic industrial sheet forming parts. Presently, forming a sheet of 0.5 mm thick is considered a technical challenge by industry, and it is conquered as demonstrated in this paper.Gas forming technique applied to Mg alloy is unprecedented and shows potential for industrial utilization.

  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. Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2016-12-01

    Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

  4. 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

  5. Microstructures and mechanical properties of hot rolled AZ31 Mg alloy sheets

    Institute of Scientific and Technical Information of China (English)

    FAN Li-kun; DONG Jie; ZHANG Ping; ZENG Xiao-qin

    2006-01-01

    The microstructures and mechanical properties of hot rolled AZ31 Mg alloy sheets were studied to understand the microstructure evolution during AZ31 Mg alloy hot rolling process. The roller was heated to 180 ℃ with burning hydrogen, and the extruded plates were rolled at 400 ℃ from 10 to 1 mm with a reduction of 30% in thickness per pass. The result shows that there is no side-cracking of these rolled sheets every pass. The extruded microstructures are greatly refined and mechanical properties are improved. The fine grains of about 4 μm were obtained of the final 0.9 mm sheets.

  6. 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.

  7. 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...

  8. Forming of a super plastic sheet metal made of MgAZ31 alloy

    Science.gov (United States)

    Zaid, Adnan I. O.; Al-Matari, Mustafa A. A.; Nazzal, M. A. H.

    2016-08-01

    Metal forming industries are constantly looking for advanced innovation, economical and energy efficient techniques. Superplastic forming has a great potential to be one of those advanced forming methods. It is a near net shape forming process which uses a unique type of materials where elongation exceeds 200% during a controlled forming conditions, e.g. temperature, pressure, and strain rate. Most of superplastic materials are formed by gas technique at elevated temperature. The main objectives of the research work in this paper were: to study the effects of the forming schemes on the forming time and thickness distribution of the formed and device a method to improve the forming part thickness and its uniformity distribution and the forming time. In this paper, a hydraulic and heating system were designed and manufactured to facilitate the experimental investigation. The superplastic magnesium alloy AZ31, Mg AZ31, was formed at 350°C with different strain rates to investigate the effect of the forming pressure profiles on the thickness uniformity of the superplastic formed part. The pressure profiles were generated based on Dutta and Mukherjee analytical approach. Finally, a variable strain rate method is modified to improve the uniformity of the thickness distribution of the formed part and reduce the forming time; which is a major limitation of superplastic forming.

  9. 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.

  10. 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.

  11. 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.

  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. 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.

  17. Influence of artificial biological fluid composition on the biocorrosion of potential orthopedic Mg-Ca, AZ31, AZ91 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X N; Zheng, Y F [State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Chen, L J, E-mail: yfzheng@pku.edu.c [School of Material Science and Engineering, Shengyang University of Technology, Shenyang 110023 (China)

    2009-12-15

    The electrochemical behavior of potential orthopedic Mg-Ca, AZ31 and AZ91 alloys was studied in Hank's solution, Dulbecco's Modified Eagle's Medium (DMEM) and serum-containing medium (DMEM adding 10% fetal bovine serum (DMEM+FBS)) over a 7 day immersion period. The biocorrosion of the above three alloys for various immersion time intervals was investigated by linear polarization and electrochemical impedance spectroscopy (EIS). After 7 day immersion, potentiodynamic polarization tests were carried out and the surface morphologies of experimental samples were examined by scanning electron microscopy (SEM) observation complemented by energy-disperse spectrometer (EDS) analysis. It was shown that the corrosion of magnesium alloys was influenced by the composition of the solution. The results indicated that chloride ion could reduce the corrosion resistance and the hydrocarbonate ions could induce rapid surface passivation. The adsorbed amino acid on the experimental magnesium alloys' surface increased their polarization resistance and reduced current densities. The influence of the serum protein on corrosion was found to be associated with the magnesium alloy compositions. A Mg-Ca alloy exhibited an increased corrosion rate in the presence of serum protein. An AZ31 alloy showed an increased corrosion rate in DMEM+FBS in the initial 3 day immersion and the corrosion rate decreased thereafter. An AZ91 alloy, with high Al content, showed a reduced corrosion rate with the addition of FBS into DMEM.

  18. Influence of artificial biological fluid composition on the biocorrosion of potential orthopedic Mg-Ca, AZ31, AZ91 alloys.

    Science.gov (United States)

    Gu, X N; Zheng, Y F; Chen, L J

    2009-12-01

    The electrochemical behavior of potential orthopedic Mg-Ca, AZ31 and AZ91 alloys was studied in Hank's solution, Dulbecco's Modified Eagle's Medium (DMEM) and serum-containing medium (DMEM adding 10% fetal bovine serum (DMEM+FBS)) over a 7 day immersion period. The biocorrosion of the above three alloys for various immersion time intervals was investigated by linear polarization and electrochemical impedance spectroscopy (EIS). After 7 day immersion, potentiodynamic polarization tests were carried out and the surface morphologies of experimental samples were examined by scanning electron microscopy (SEM) observation complemented by energy-disperse spectrometer (EDS) analysis. It was shown that the corrosion of magnesium alloys was influenced by the composition of the solution. The results indicated that chloride ion could reduce the corrosion resistance and the hydrocarbonate ions could induce rapid surface passivation. The adsorbed amino acid on the experimental magnesium alloys' surface increased their polarization resistance and reduced current densities. The influence of the serum protein on corrosion was found to be associated with the magnesium alloy compositions. A Mg-Ca alloy exhibited an increased corrosion rate in the presence of serum protein. An AZ31 alloy showed an increased corrosion rate in DMEM+FBS in the initial 3 day immersion and the corrosion rate decreased thereafter. An AZ91 alloy, with high Al content, showed a reduced corrosion rate with the addition of FBS into DMEM.

  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. 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.

  1. 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...

  2. 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.

  3. 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

  4. 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.

  5. 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...

  6. 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.

  7. Microstructure and Mechanical Properties of Hybrid Laser-Friction Stir Welding between AA6061-T6 Al Alloy and AZ31 Mg Alloy

    Institute of Scientific and Technical Information of China (English)

    Woong-Seong Chang; S.R.Rajesh; Chang-Keun Chun; Heung-Ju Kim

    2011-01-01

    For the purpose of improving the strength of this dissimilar joint, the present study was carried out to investigate the improvement in intermetallic layer by using a third material foil between the faying edges of the friction stir welded and hybrid welded Al6061-T6/AZ31 alloy plates. The difference in microstructural and mechanical characteristics of friction stir welded and hybrid welded Al6061-T6/AZ31 joint was compared. Hybrid buttwelding of aluminum alloy plate to a magnesium alloy plate was successfully achieved with Ni foil as filler material, while defect-free laser-friction stir welding (FSW) hybrid welding was achieved by using a laser power of 2 kW. Transverse tensile strength of the joint reached about 66% of the Mg base metal tensile strength in the case of hybrid welding with Ni foil and showed higher value than that of the friction stir welded joint with and without the third material foil. This may be due to the presence of less brittle Ni-based intermetallic phases instead of Al12Mg17.

  8. 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.

  9. Investigation on the effect of titanium (Ti) addition to the Mg- AZ31 alloy in the as cast and after extrusion conditions on its metallurgical and mechanical characteristics

    Science.gov (United States)

    Zaid, Adnan I. O.; Raghad; Hememat, S.

    2016-08-01

    Magnesium-aluminum alloys are versatile materials which are used in manufacturing a number of engineering and industrial parts in the automobile and aircraft industries due to their strength - to -weight -ratios. Against these preferable characteristics, magnesium is difficult to deform at room temperature; therefore it is alloyed with other elements mainly aluminum and zinc to add some required properties particularly to achieve high strength -to- weight ratio. Grain refinement is an important technology to improve the mechanical propertiesand the microstructure uniformity of the alloys. Most of the published work on grain refinement was directed toward grain refining aluminum and zinc alloys; however, the effect of the addition of rare earth material on the grain size or the mechanical behavior of Mg alloys is rare. In this paper the effect of Ti addition on the grain size, mechanical behavior, ductility, extrusion force and energy, of Mg-AZ31 alloy both in the as cast condition and after direct extrusion is investigated.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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。

  15. Effect of Fe{sup 3+} ions on the thermal and optical properties of the ceramic coating grown in-situ on AZ31 Mg Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lu Songtao [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Qin Wei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wu Xiaohong, E-mail: wuxiaohong@hit.edu.cn [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Wang Xiaodong [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Zhao Guimei [China Academy of Space Technology, Beijing 100094 (China)

    2012-07-16

    This research investigates the effect of Fe{sub 2}(SO{sub 4}){sub 3} on the thermal and optical properties of the ceramic coatings formed on AZ31 Mg alloy. The different ceramic coatings were obtained by plasma electrolytic oxidation (PEO) in electrolytes that contain varied concentrations of Fe{sub 2}(SO{sub 4}){sub 3}. The microstructure, element distribution, composition as well as the thermal and optical properties of the coatings were studied with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), UV-VIS-NIR spectrophotometer and infrared reflectometer. The results show that all of the coatings prepared were mainly composed with MgO, with trace-amount of Fe{sub 3}O{sub 4} presents and Fe seems entered into the MgO crystal structure. With the increasing of the concentration of Fe{sub 2}(SO{sub 4}){sub 3}, the solar absorptance and infrared emittance increased initially but then remain stable. We found that at the concentrations 8 g L{sup -1}, the coating has the highest solar absorptance (0.94) and infrared emittance (0.83). Our results show that coatings formed with this method could be useful as a thermal control coating in a variety of applications, such as in the spacecraft. - Highlights: Black-Right-Pointing-Pointer Thermal control coatings on AZ31 Mg alloy were prepared by the plasma electrolytic oxidation (PEO) method. Black-Right-Pointing-Pointer The coatings were mainly composed with MgO, with trace-amount of Fe{sub 3}O{sub 4} presents. Black-Right-Pointing-Pointer The using of Fe{sup 3+} in the electrolyte improves the thermal and optical properties of the obtained MgO coating. Black-Right-Pointing-Pointer The thermal control coating obtained by PEO has high solar absorptance (0.94) and infrared emittance (0.83).

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. On the deformation twinning of Mg AZ31B

    DEFF Research Database (Denmark)

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

    2015-01-01

    variants was non-negligible. The CPFE simulation indicates that there is a small variation in the stress within each grain in the elastic regime, which increases drastically upon the onset of plasticity. One of the significant outcomes of this work is the new statistical information on the interaction...... 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......-ray diffraction (3DXRD) was used to map the center-of-mass positions, volumes, orientations, elastic strains, and stress tensors of over 1400 grains in-situ up to a true strain of 1.4%. More than 700 tensile twins were observed to form in the mapped volume under deformation. The measured center-of-mass positions...

  3. 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.

  4. 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.

  5. AZ31B镁合金焊接接头的疲劳裂纹扩展行为%Fatigue Crack Propagation Behavior of as-Extruded AZ31B Mg Alloy Welded Joint

    Institute of Scientific and Technical Information of China (English)

    张红霞; 裴飞飞; 闫志峰; 王文先; 梁培阳; 李娟; 卫英慧

    2012-01-01

    The fatigue crack propagation behavior of as-extruded AZ31B magnesium alloy welded joint and heat affected zone have been studied.Compact tensions [C(T)] of welded joint [L-T(W)] and heat affected zone(welded joint is parallel [T-L(H)]and vertical [L-T(H)] to the extruded direction) were researched.Results indicate that the crack propagation direction is parallel to the extrusion direction for L-T(W); fatigue crack propagation rate is a rapid-slow process.T-L(H) is parallel to the notch direction and L-T(H) can be divided into two states (i.e.,parallel to or angularly deflected towards the notch direction);crack propagation rate initially goes through a rapid course before it slows down.The fracture modes of crack tip remain a mixed-mode of transgranular and intergranular fractures.The fatigue fracture consists of quasi-cleavage and is a brittle fracture.%对AZ31B镁合金焊接接头和热影响区的疲劳裂纹扩展行为进行研究,分析了焊接接头[L-T(W)]和热影响区的紧凑拉伸试验[C(T)],其中热影响区的C(T)试验包括焊缝平行于挤压方向[T-L(H)]和垂直于挤压方向[L-T(H)]两种.结果表明:对于L-T(W)试样,裂纹沿挤压方向扩展,裂纹扩展经历先快后慢的扩展过程;T-L(H)试样裂纹平行于缺口方向扩展,L-T(H)试样裂纹为平行于缺口方向和与缺口成一定角度两种扩展方向,裂纹扩展经历先慢后快的扩展过程.裂纹尖端扩展为穿晶和沿晶的混合模式,疲劳断口为准解理特征的脆性断口.

  6. 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.

  7. A Phase-field Model to Simulate Recrystallization in an AZ31 Mg Alloy in Comparison of Experimental Data

    Institute of Scientific and Technical Information of China (English)

    Mingtao WANG; B.Y.Zong; Gang WANG

    2008-01-01

    A model has been established to simulate the realistic spatio-temporal microstructure evolution in recrystal-lization of a magnesium alloy using the phase field approach.A set of rules have been proposed to decide the real physical value of all parameters in the model.The thermodynamic software THERMOCALC is applied to determine the local chemical free energy and strain energy,which is added to the free energy density of grains before recrystallization.The Arrhenius formula is used to describe boundary mobility and the activity energy is suggested with a value of zinc segregation energy at the boundary.However,the mobility constant in the formula was found out by fitting to a group of grain size measurements during recrystallization of the alloy.The boundary range is suggested to decide the gradient parameters in addition of fitting to the experimental boundary energy value.These parameter values can be regarded as a database for other similar simulations and the fitting rules can also be applied to build up databases for any other alloy systems.The simulated results show a good agreement with reported experimental measurement of the alloy at the temperatures from 300 to 400℃ for up to 100 min but not at 250℃.This implies a mechanism variation in activity energy of the boundary mobility in the alloy at low temperature.

  8. 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.

  9. 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.

  10. 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)

  11. 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)

  12. 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...

  13. 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

  14. Microstructure and Tensile Properties of AZ31B Alloy and AZ31B-SiCp Deformed Through a Multi-step Process

    Science.gov (United States)

    Shen, M. J.; Wang, X. J.; Ying, T.; Zhang, M. F.; Wu, K.

    2016-10-01

    The 15 vol.% micron SiC particle (SiCp)-reinforced AZ31B magnesium matrix composite (AZ31B-SiCp) prepared with semisolid stirring-assisted ultrasonic vibration was subjected to a multi-step process. The influence of the multi-step processing route on the microstructure and mechanical properties of the AZ31B-SiCp was investigated. For comparison, the monolithic AZ31B alloy was also processed under the same conditions. The results showed that the grain sizes of the AZ31B alloy and the AZ31B-SiCp were gradually decreased with increasing the processing step. Compared with the AZ31B-SiCp, the grain size of the AZ31B alloy was much larger, and the grain size distribution was inhomogeneous at the same processing condition. The particles of the AZ31B-SiCp were dispersed uniformly through the multi-step processing. Moreover, the tensile properties of the materials were gradually improved with increasing the processing step. In particular, the strength of AZ31B-SiCp and the ductility of AZ31B alloy improved significantly based on the room-temperature tensile test results.

  15. Microstructure and Tensile Properties of AZ31B Alloy and AZ31B-SiCp Deformed Through a Multi-step Process

    Science.gov (United States)

    Shen, M. J.; Wang, X. J.; Ying, T.; Zhang, M. F.; Wu, K.

    2016-08-01

    The 15 vol.% micron SiC particle (SiCp)-reinforced AZ31B magnesium matrix composite (AZ31B-SiCp) prepared with semisolid stirring-assisted ultrasonic vibration was subjected to a multi-step process. The influence of the multi-step processing route on the microstructure and mechanical properties of the AZ31B-SiCp was investigated. For comparison, the monolithic AZ31B alloy was also processed under the same conditions. The results showed that the grain sizes of the AZ31B alloy and the AZ31B-SiCp were gradually decreased with increasing the processing step. Compared with the AZ31B-SiCp, the grain size of the AZ31B alloy was much larger, and the grain size distribution was inhomogeneous at the same processing condition. The particles of the AZ31B-SiCp were dispersed uniformly through the multi-step processing. Moreover, the tensile properties of the materials were gradually improved with increasing the processing step. In particular, the strength of AZ31B-SiCp and the ductility of AZ31B alloy improved significantly based on the room-temperature tensile test results.

  16. 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.

  17. 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.

  18. Al 7075和Mg AZ31合金扩散连接:工艺参数、显微组织分析和力学性能%Diffusion bonding of Al 7075 and Mg AZ31 alloys:Process parameters, microstructural analysis and mechanical properties

    Institute of Scientific and Technical Information of China (English)

    Seyyed Salman SEYYED AFGHAHI; Mojtaba JAFARIAN; Moslem PAIDAR; Morteza JAFARIAN

    2016-01-01

    Al 7075 and Mg AZ31 alloys were joined by diffusion bonding method. Joining process was performed in pressure range of 10−35 MPa at temperatures of 430−450 °C for 60 min under a vacuum of 13.3 MPa. The microstructure evaluation, phase analysis and distribution of elements at the interface were done using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The pressure of 25 MPa was determined as the optimum pressure in which the minimum amount of plastic deformation takes place at the joint. Different reaction layers containing intermetallic compounds, such as Al12Mg17, Al3Mg2 andα(Al) solid solution, were observed, in interfacial transition zone (ITZ). Thickness of layers was increased with increasing the operating temperature. According to the results, diffusion of aluminum atoms into magnesium alloy was more and the interface movement towards the Al alloy was observed. The maximum bond strength of 38 MPa was achieved at the temperature of 440 °C and pressure of 25 MPa. Fractography studies indicated that the brittle fracture originated from Al3Mg2 phase.%采用扩散连接方法在压力范围10~35 MPa、温度430~450°C、时间60 min,真空13.3 mPa条件下连接Al 7075和 Mg AZ31合金。采用扫描电子显微镜、X射线能谱和X射线衍射分析合金的显微组织演变、相分析和元素分布。结果表明:25 MPa 为最佳的压力条件,在此条件下接头发生最小的塑性变形;在界面过渡区可观察到含不同金属间化合物如Al12Mg17, Al3Mg2和α(Al)的固溶体反应层;随着温度的升高,反应层的厚度增大,更多的铝原子扩散进入镁合金,且界面朝着铝合金移动;在温度440°C、压力25 MPa下得到最大的结合强度38 MPa。断口形貌研究表明,脆性断裂来自于Al3Mg2相。

  19. 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.

  20. 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%.

  1. MICROSTRUCTURAL STUDIES OF FRICTION STIR WELDED AZ31 MAGNESIUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    H.Zhang; S.B.Lin; L.Wu; J.C.Feng

    2004-01-01

    Friction stir welding achieves the weld in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welding tool, which results in changes in the local microstructure of magnesium alloy. The purpose in the paper is to study the microstructures of friction stir welded AZ3I magnesium alloy. Residual microstructures,including dynamic re-crystallization zone and nugget structures have been systematically investigated utilizing optical microscopy (OM), scanning electric microscopy (SEM),transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness. AZ31 magnesium alloy has been successfully friction stir welded and exhibits the variations of microstructure including dynamically recrystallized,equaxied grains in the weld nugget. Residual hardness in the nugget was found slightly lower than the parent but not too obvious.

  2. Friction stir welding of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    林三宝; 张华; 吴林; 冯吉才; 戴鸿滨

    2003-01-01

    Friction stir welding (FSW) is an new solid-phase joining technology which has more advantages over fusion welding methods in welding of aluminum and other non-ferrous metals. The effects of welding parameters on mechanical properties and microstructure during friction stir welding of AZ31 magnesium alloy were studied in this paper. Microstructures and mechanical properties of the joints were investigated by means of optical microscopy, scanning electric microscopy (SEM), micro-hardness analysis, and tensile test. Experimental results show that the magnesium alloy can be successfully welded by FSW method, and the ultimate tensile strength (UTS) of FSW joint reaches up to 90 percent of base metal. The microstructures of welded joints exhibit the variation from dynamically recrystallized fine grains to greatly deformed grains. Hardness in nugget zone was found lower than the base metal but not too obvious.

  3. 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.

  4. Chemical conversion coating on AZ31B magnesium alloy and its corrosion tendency

    Institute of Scientific and Technical Information of China (English)

    Hualan JIN; Xiangjie YANG; Ming WANG

    2009-01-01

    The morphology change of the magnesium matrix after pre-treatment and the mor-phology as well as the phase composition of chemical conversion coating formed by phosphate were studied using scanning electron microscope and X-ray diffraction. The corrosion resistance of the coating was studied by salt spray and damp test, and the corrosion tendency during salt immersion test was analyzed. The results show that the phase composition before and after pre-treatment is almost change- less, and the deep microflaw appears between α and β phases during acidic pickling. The phosphate conversion coating is mainly composed of Mg, MgO, and some amor-phous phase, and it can provide a good protection for the AZ31B alloy. Results from corrosive morphology indicate that the growth and the corrosion resistance of the phosphate conversion coating are related to the forming process of the AZ31B matrix.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. TiO2 Deposition on AZ31 Magnesium Alloy Using Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Leon White

    2013-01-01

    Full Text Available Plasma electrolytic oxidation (PEO has been used in the past as a useful surface treatment technique to improve the anticorrosion properties of Mg alloys by forming protective layer. Coatings were prepared on AZ31 magnesium alloy in phosphate electrolyte with the addition of TiO2 nanoparticles using plasma electrolytic oxidation (PEO. This present work focuses on developing a TiO2 functional coating to create a novel electrophotocatalyst while observing the surface morphology, structure, composition, and corrosion resistance of the PEO coating. Microstructural characterization of the coating was investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM followed by image analysis and energy dispersive spectroscopy (EDX. The corrosion resistance of the PEO treated samples was evaluated with electrochemical impedance spectroscopy (EIS and DC polarization tests in 3.5 wt.% NaCl. The XRD pattern shows that the components of the oxide film include Mg from the substrate as well as MgO and Mg2TiO4 due to the TiO2 nanoparticle addition. The results show that the PEO coating with TiO2 nanoparticles did improve the corrosion resistance when compared to the AZ31 substrate alloy.

  10. 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.

  11. 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.

  12. Effects of grain refinement on mechanical properties and microstructures of AZ31 alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cerium was added in AZ31 alloy with the contents of 0.4%, 0.8% and 1.2% respectively to produce experimental alloys.The grain refinement of Ce in the as-east and rolled AZ31 alloy were studied by using Polyvar-MET optical microscope with a VSM2000 quantitative analysis system, KYKY2000 SEM and Tecnai G2 20 TEM. And the mechanical properties of AZ31+Ce alloy were tested on a CSS-44100 testing system with computerized data acquisition. The results show that the cerium has a good grain refinement effect on the as-cast AZ31 alloy because cerium can build up a solute enriched zone rapidly during the solidification process. The dynamic recrystallization (DRX) grains less than 10 μm can be obtained in hot rolled AZ31+Ce alloy. A cold rolling deformation degree over than 20% and a following annealing at 400 ℃ for 1h will lead to refine and uniform grains with the sizes of about 25μm. The cerium can form dispersed and thermally stable Al4Ce phase that can prohibit the coarsening of grains in AZ31 +Ce alloy during the hot rolling and annealing process.

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Mechanical properties of AZ31 alloy processed by a green metallurgy route; Propiedades mecanicas de la aleacion AZ31 procesada por una ruta eco-sostenible

    Energy Technology Data Exchange (ETDEWEB)

    D' Enrico, F.; Garces, G.; Hofer, M.; Kim, S. K.; Perez, P.; Cabeza, S.; Adeva, P.

    2013-07-01

    Recently it has been proved that molding of defect-free components of various commercial alloys of magnesium can be carried out successfully when small amounts of CaO are added to the melt, making unnecessary the use of SF{sub 6} 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 CaAl{sub 2} 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 demonstrated that alloys processed from chips exhibit the highest tensile stress values, close to 320 MPa. (Author)

  19. 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.;

    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......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...

  20. Effects of Solution Treatment on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy at Elevated Temperature%固溶处理对AZ31合金组织与高温力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    王敏; 张敏刚; 孙述利; 孙钢; 柴跃生

    2012-01-01

    Influences of solution treatment on microstructure and mechanical properties of AZ31 magnesium alloy were investigated by Zeiss microscope and X-ray diffraction. The results show that the tensile strength of AZ31 magnesium alloy is increased from 69. 7 Mpa to 86. 6 Mpa with solid solution treatment at 688K from 6 h to 12 h. The β-Mg17 Al12 phase in the microstructure of the AZ31 magnesium is gradually dissolved into the matrix phase after solid solution at 688 K for 12 h. With increasing in the solution time, the static recrystallization in the magnesium alloy can be fully undergone, and a large a-mount of fine recrystallization grains with the average size of 10 μm are generated at the boundary of the AZ31 magnesium alloy after the solid solution at 688 K for 12 h.%采用Zeiss金相显微镜、XRD射线衍射仪研究了不同固溶处理条件对AZ31镁合金的组织及性能的影响.结果表明,AZ31合金的抗拉强度随着固溶时间的延长得到明显提高(由688 K固溶处理6h的69.7 MPa升至12 h的86.6MPa);经过688 K×12h固溶处理的AZ31合金组织中的β-Mg17Al12相逐渐溶解,最后完全溶入基体中;固溶时间的延长保证了再结晶过程的充分进行,688 K固溶处理12h的合金组织晶界处产生了大量平均尺寸为10 μm的细小再结晶晶粒.

  1. 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.

  2. 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

  3. 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.

  4. Effect of cerium and lanthanum additives on plasma electrolytic oxidation of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    沈德久; 马豪杰; 郭长虹; 蔡景瑞; 李国龙; 何东磊; 杨庆祥

    2013-01-01

    Plasma electrolytic oxidation (PEO) coatings on AZ31 magnesium (Mg) alloy were developed using the aqueous solution with alkaline silicate and sodium hydroxide as a base electrolyte system. The effects of cerium (Ce) nitrate and lanthanum (La) nitrate additives on the voltage response, microstructure, compositions and corrosion resistance of PEO coatings were investigated by scan-ning electron microscopy (SEM), energy-dispersive spectrum (EDS), X-ray diffraction (XRD) and potentiodynamic polarization tests, etc. The results showed that Ce and La additives increased the stable voltage and compactness of the PEO coatings, while, those did not change the compositions of the PEO coatings. The corrosion resistance of the PEO coating obtained in solutions with La nitrate of 0.1 g/L was the best, followed by that with Ce nitrate of 0.1 g/L and that without additives.

  5. 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

  6. 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.

  7. Damage and Failure Analysis of AZ31 Alloy Sheet in Warm Stamping Processes

    Science.gov (United States)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2016-07-01

    In this study, a combined experimental-numerical investigation on the failure of AZ31 Mg alloy sheet in the warm stamping process was carried out based on modified GTN damage model which integrated Yld2000 anisotropic yield criterion. The constitutive equations of material were implemented into a VUMAT subroutine for solver ABAQUS/Explicit and applied to the formability analysis of mobile phone shell. The morphology near the crack area was observed using SEM, and the anisotropic damage evolution at various temperatures was simulated. The distributions of plastic strain, damage evolution, thickness, and fracture initiation obtained from FE simulation were analyzed. The corresponding forming limit diagrams were worked out, and the comparison with the experimental data showed a good agreement.

  8. 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.

  9. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    Institute of Scientific and Technical Information of China (English)

    Rui-ze Wang; Zhang-hua Chen; Yu-jie Li; Chao-fang Dong

    2013-01-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill’s quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at diff erent temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at diff erent temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal eff ects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at diff erent stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  10. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    Science.gov (United States)

    Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang

    2013-12-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  11. Phosphating process of AZ31 magnesium alloy and corrosion resistance of coatings

    Institute of Scientific and Technical Information of China (English)

    CHENG Ying-liang; WU Hai-lan; CHEN Zhen-hua; WANG Hui-min; LI Ling-ling

    2006-01-01

    Zinc phosphate films were formed on AZ31 magnesium alloy by immersing into a phosphatation bath to enhance the corrosion resistance of AZ31. Different films were prepared by changing the processing parameters such as immersing time and temperature. The corrosion protection of the coatings was studied by electrochemical measurements such as electrochemical impedance spectroscopy, potentiodynamic polarization curves, and the structure of the films were studied by metalloscopy and X-ray diffraction (XRD). The results show that, the film formed at 80 ℃, 10 min has the highest corrosion resistance. The XRD patterns show that the film consists of hopeite (Zn3(PO4)2·xH2O).

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. Torsional and axial damping properties of the AZ31B-F magnesium alloy

    Science.gov (United States)

    Anes, V.; Lage, Y. E.; Vieira, M.; Maia, N. M. M.; Freitas, M.; Reis, L.

    2016-10-01

    Damping properties for the AZ31B-F magnesium alloy were evaluated for pure axial and pure shear loading conditions at room temperature. Hysteretic damping results were measured through stress-strain controlled tests. Moreover, the magnesium alloy viscous damping was measured with frequency response functions and free vibration decay, both results were obtained by experiments. The axial and shear damping ratio (ASDR) has been identified and described, specifically for free vibration conditions.

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. 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.

  3. Theoretical and experimental research of hammer forging process of RIM from AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    A. Gontarz

    2014-10-01

    Full Text Available The results of theoretical analysis and experimental tests of hammer forging process of rim part from AZ31 magnesium alloy are presented in this paper. On the basis of numerical simulation results, the analysis of limiting phenomena was made. These phenomena include: possibility of overlapping presence, not filling of die impression, overheating of material and cracks. The results of theoretical analysis provided the support for planning of experimental tests in industrial conditions. Forging tests were conducted in one of Polish forming plants, applying steam-air hammer of blow energy 63 kJ. On the basis of experimental verification, it was stated that it is possible to obtain rim forging from AZ31 alloy of assumed quality in the hammer forging process.

  4. Corrosion protection of AZ31 magnesium alloy treated with La3+ modified 3-methacryloxypropyltrimethoxysilane conversion film

    Institute of Scientific and Technical Information of China (English)

    乔英杰; 李文鹏; 王桂香; 张晓红

    2015-01-01

    This study demonstrated the influence of addition concentration of La3+ on the anti-corrosion behavior of a 3-methacry-loxypropyltrimethoxysilane (MPS) film formed on AZ31 magnesium alloy. The morphology and surface chemistry of the samples were evaluated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The corrosion resistance of the pre-treated AZ31 magnesium alloy was studied during immersion in 0.1 mol/L NaCl solution, using poten-tiodynamic polarization curves and electrochemical impedance spectra (EIS). In comparison to MPS film, the low concentration of La3+ ion modified silane layer exhibited a better anti-corrosion performance, nevertheless, the high concentration of La3+ ion modified was worse. Results showed that the preferable addition concentration of La3+ ion in the silane film was 5×10–4 mol/L in this experi-ment.

  5. 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)

  6. 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.

  7. AZ31镁合金表面聚吡咯的化学氧化合成及其耐蚀性能%Chemical Oxidative Polymerization of Polypyrrole and Its Corrosion Resistance on the AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    黄荣; 陈明安; 路学斌

    2011-01-01

    以对甲苯磺酸钠为掺杂剂,三氯化铁为氧化剂,用化学氧化聚合法在AZ31镁合金表面制备聚吡咯(PPy)膜.采用傅里叶变换红外(FTIR)光谱分析了镁合金表面聚吡咯膜结构,通过电化学极化曲线、电化学阻抗谱(EIS)研究了其耐蚀性能,通过扫描电子显微镜(SEM)、X射线能量散射谱(EDS)分析了表面形貌和成分.和镁合金裸样相比,聚吡咯膜对镁合金腐蚀有一定的抑制作用.硅烷预处理改善了镁合金/聚吡咯体系的耐腐蚀性能,使腐蚀电位较镁合金裸样正移了110 mV,电流密度减小了约2个数量级.%Polypyrrole (PPy) was chemically synthesized from pyrrole using sodium p-toluenesulfonate as a doping agent and ferric chloride as an oxidant on the surface of the AZ31 magnesium alloy.Fourier transform infrared (FTIR) spectroscopy was used for structural characterization of the PPy film.The corrosion behavior of the PPy coated AZ31 Mg alloy was studied using an electrochemical polarization test and electrochemical impedance spectroscopy (EIS).Scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDS) were used to observe the surface morphology and for elemental analysis of the film, respectively.The PPy film showed a certain corrosion inhibition on the AZ31 magnesium alloy.Silane pretreatment can improve the corrosion protection performance of the Mg/PPy system causing a positive shift of the corrosion potential by 110 mV and a decrease in the corrosion current density by two orders of magnitude compared with that of AZ31 Mg alloy.

  8. 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...

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Influence of chemical liquids on the fatigue crack growth of the AZ31 magnesium alloy

    Science.gov (United States)

    Wang, Zhang-Zhong; He, Xian-Cong; Bai, Yun-Qiang; Ba, Zhi-Xin; Dai, Yu-Ming; Zhou, Heng-Zhi

    2012-03-01

    The fatigue crack growth behavior of an AZ31 magnesium alloy was investigated by comparing the effect of zirconate and phosphate chemical liquids. The morphology, components, and phase compositions of the chemical depositions at the fatigue crack tip were analyzed by employing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. For samples with and without the chemical liquids, their stress-intensity factor values at the fatigue crack tip were compared by using a stress-strain gauge. The results demonstrated that a zirconate film (Zr x O y ·Zn x O y ) and a phosphate film (Zn3(PO4)2·4H2O and MgZnP2O7) could be formed on the fatigue crack-surface at the fatigue crack tip. The stress distribution was changed because of the chemical depositions and the causticity of the chemical liquids. This could decrease the stress-intensity factor value and thus effectively cause fatigue crack closure, which reduces the fatigue crack growth rate. Moreover, it was found that the fatigue crack closure effect of zirconates was more positive than that of phosphates.

  16. 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)

  17. 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.

  18. 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%.

  19. 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

  20. Research status and development tendency of welding technology of AZ31B magnesium alloy%AZ31B镁合金焊接技术研究现状及发展方向

    Institute of Scientific and Technical Information of China (English)

    刘奋军; 王憨鹰

    2013-01-01

    Welding characteristics of magnesium alloy are analyzed,and welding processes of AZ31B magnesium alloy are introduced,including laser welding,brazing,diffusion welding,friction stir welding,TIG,electron beam welding and so on. The future directions of welding technology of AZ31B magnesium alloy are pointed out.%分析镁合金的焊接特点,综述了近年来AZ31B镁合金的焊接方法,包括激光焊、钎焊、扩散焊、搅拌摩擦焊、TIG焊、电子束焊等,展望了AZ31B镁合金的焊接研究方向。

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    Liu Di

    2015-01-01

    Full Text Available 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.

  3. 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.

  4. Experimental study of fluoride coating on the degradation of magnesium alloy AZ31B in vitro%氟涂层对AZ31B镁合金植入初期降解作用的影响

    Institute of Scientific and Technical Information of China (English)

    钟丽芳; 李洪洋; 王秋旭; 艾红军

    2011-01-01

    目的 观察氟涂层对AZ31B镁合金植入初期降解速度的影响.方法 分别将无涂层(对照组)和氟涂层(观察组)的AZ31B镁合金浸泡于骨细胞培养基DMEM溶液(模拟体液),分别于浸泡1、3、5、7、14 d时后观察两组模拟体液pH值,扫描电镜下观察两组浸泡前和浸泡7 d时AZ31B镁合金材料表面形貌.结果 对照组镁合金浸泡1、3、5、7、14 d模拟体液pH值分别为7.51±0.15、8.32±0.10、9.36±0.10、9.79±0.09、9.87±0.09,呈升高趋势,观察组分别为7.29±0.07、7.44±0.06、7.47±0.11、7.65±0.11、7.74±0.08,各时点pH值相比,P均>0.05.对照组浸泡前镁合金表面相对光滑,观察组镁合金表面致密、光滑,有一些同向的纹理;浸泡7 d后,无涂层AZ31B镁合金表面呈龟裂状;氟涂层AZ31B镁合金表面无明显改变,可见散在腐蚀凹陷.结论 氟涂层可以在一定程度上抑制AZ31B镁合金植入初期的降解作用.%Objective To study the viability of using magnesium alloy AZ31B coated with fluoride as biodegradable bone scaffolds materials.Methods Pieces of magnesium alloy AZ31B uncoated and coated with fluoride were immersed in DMEM culture medium respectively.The changes of the DMEM culture medium's pH valules and morphology of magnesium alloy AZ31B uncoated or coated were evaluated after immersion.Results The pH values of DMEM solution immersed by magnesium alloy AZ31B uncoated after 1, 3, 5, 7, 14 d were 7.51 ±0.15, 8.32 ±0.10, 9.36 ±0.10, 9.79 ±0.09,9.87 ± 0.09, while that immersed by magnesium alloy AZ31B ooated with flouride were 7.29 ± 0.07, 7.44 ± 0.06, 7.47 ± 0.11,7.65 ± 0.1 1, 7.74 ± 0.08 ( all P > 0.05 ).Before immersed, the surface of magnesium alloy AZ31B was smooth,while magnesium alloy AZ31B coated with fluoride was density and smooth texture.After immersed for 7 d, the surface of magnesium alloy AZ31B uncoated was corroded severely and the surface of magnesium alloy AZ31B coated with fluoride changed a little and

  5. Study on Microstructure and Properties of the Broadloom AZ31B Magnesium Alloy Roll-casting Plate%宽幅AZ31B镁合金铸轧板显微组织和性能研究

    Institute of Scientific and Technical Information of China (English)

    黄志权; 黄庆学; 马立峰; 林金保; 庞志宁

    2013-01-01

    The microstructure of broadloom AZ31B magnesium alloy roll-casting plate and its influence on the edge crack and mechanical properties of the plate were studied by using metallographic observation,SEM and mechanical property testing experiment.The results show that:the plate organization is mainly composed of α-Mg matrix,β-Mg17Al12 phase and α +β divorced eutectic,showing dendritic morphology; In surface and edge of the plate,β-Mg17Al12 phase is mainly distributed at the grain boundary and the density is bigger,formed net-shape; In center and central of the plate,spherical β-Mg17Al12 phase is dispersed in α-Mg matrix,formed lamellar-shape; The main reason for the edge crack in the cast-rolling process is in the slab edge interdendritic low-melting eutectic phase and β-Mg17Al12 phase of grain boundary which are easy to be crack source,and extend outward along the crystal; The tensile specimen showes brittle cleavage fracture characteristics,and its mechanical property is obvious anisotropy.%通过金相观测、断口扫描和力学性能测试等实验,研究了宽幅AZ31B镁合金铸轧板的组织分布,及其对板带边裂和力学性能的影响.结果表明:AZ31B镁合金铸轧板的组织主要由a-Mg基体、析出相β-Mg17Al12相及α+β离异共晶组成,呈树枝晶形貌;β-Mg17Al12相在AZ31B镁合金铸轧板坯的表层及边部主要分布于晶界处且密度较大、构成网状,而在板坯的心部和中部呈球状弥散于α-Mg基体中,构成层片状;在板坯边部枝晶间低熔点的共晶相及晶界上的β-Mg17Al12相易成为裂纹源,并沿晶向外扩展,是铸轧过程中产生裂纹的主要原因;试样拉伸断口呈脆性解理断裂的特征,其力学性能呈明显的各向异性.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Friction stir welding of AZ31 magnesium alloys processed by equal channel angular pressing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; YUAN Shouqian; WANG Xunhong

    2008-01-01

    Equal channel angular pressing (ECAP) is an effective thermo-mechanical process to make ultrafine grains.An investigation was carried out on the friction stir welding (FSW) of ECAPed AZ31 magnesium alloys with a thickness of 15 mm.For different process parameters,the optimum FSW conditions of ECAPed AZ31 magnesium alloys were examined.The basic characterization of weld formation and the mechanical properties of the joints were discussed.The results show that the effect of welding parameters on welding quality was evident and welding quality was sensitive to welding speed.Sound joints could be obtained when the welding speed was 37.5 mm/min and the rotation speed of the stir tool was 750 r/min.The maximum tensile strength (270 MPa) of FSW was 91% that of the base materials.The value of microhardness varied between advancing side and retreating side because of the speed field near the pin of the stir tool,which weakened the deformed stress field.The value of microhardness of the welding zone was lower than that of the base materials.The maximum value was located near the heat-affected zone (HAZ).Remarkable ductile character was observed from the fracture morphologies of welded joints.

  11. 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.

  12. 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

    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...... was investigated. Sulphuric, nitric and phosphoric acids of different concentrations were used to clean the alloy for various pickling times. The surface morphology, composition and phases were elucidated using scanning electron microscopy, X-ray fluorescence analysis, spark discharge-optical emission spectroscopy......, energy dispersive X-ray spectroscopy and infrared spectroscopy. The effect of surface cleaning on the corrosion properties was studied using salt spray test and electrochemical impedance spectroscopy. The experimental results show that acid pickling reduces the surface impurities and therefore enhances...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Microstructure and mechanical properties of friction stir welding of AZ31B magnesium alloy added with cerium

    Institute of Scientific and Technical Information of China (English)

    于思荣; 陈显君; 黄志求; 刘耀辉

    2010-01-01

    The AZ31B magnesium alloy sheet added with 0.5 wt.% Ce was welded with friction stir welding(FSW).The microstructures and mechanical properties of the welded joint were investigated.The results showed that the microstructures in the weld nugget zone were uniform and with small equiaxed grains.The grains in the heat-affected zone and the thermo-mechanical affected zone were coarser than those in the base metal zone and the weld nugget zone.The ultimate tensile strength of AZ31B magnesium alloy added with 0.5...

  18. Finite element simulation on press forging of magnesium alloy AZ31 sheets

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Press forging of rectangular box of magnesium alloy AZ31 sheets was investigated at elevated temperatures.The characteristics of metal flow were analyzed on the basis of finite element method(FEM)and experiments.Effects of friction factor and sidewall thickness on metal flow and boss forming were investigated by FEM.The results indicate that the bosses and the sidewall of the rectangular box are formed unevenly due to the uneven flow of the metal.The increase in friction factor at die/sheet interface improves the metal flow pattem and the efficiency of boss forming,but reduces the sidewall uniformity.Decrease in sidewall thickness enhances boss forming efficiency,whereas the punch load increases in this case.The present work can provide rcasonable parameters and design guideline for the practical press foxing process of magnesium alloy sheets.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Comparison of the microstructure and thermal stability of an AZ31 alloy processed by ECAP and large strain hot rolling

    Energy Technology Data Exchange (ETDEWEB)

    Eddahbi, M. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Valle, J.A. del [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Perez-Prado, M.T. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain)]. E-mail: tpprado@cenim.csic.es; Ruano, O.A. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain)

    2005-11-25

    The aim of this work is to compare the microstructure, the texture, as well as the thermal stability of an AZ31 Mg alloy processed via two different severe plastic deformation processing techniques, namely large strain hot rolling (LSHR) and equal channel angular pressing (ECAP). The microstructure was characterized by optical microscopy and the texture was measured both by X-ray diffraction and electron backscatter diffraction (EBSD). The microstructure obtained via LSHR has average grain sizes around 3 {mu}m, but it is quite heterogeneous. Additionally, a well-defined basal texture develops. ECAP gives rise to a more homogeneous and slightly coarser microstructure, with an average grain size of 7 {mu}m and a shear type texture. The higher resistance of the extruded sample to secondary recrystallization after severe post-deformation annealing is attributed to a texture effect.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. A Study on Compressive Anisotropy and Nonassociated Flow Plasticity of the AZ31 Magnesium Alloy in Hot Rolling

    Directory of Open Access Journals (Sweden)

    Guoqiang Wang

    2014-01-01

    Full Text Available Effect of anisotropy in compression is studied on hot rolling of AZ31 magnesium alloy with a three-dimensional constitutive model based on the quadratic Hill48 yield criterion and nonassociated flow rule (non-AFR. The constitutive model is characterized by compressive tests of AZ31 billets since plastic deformations of materials are mostly caused by compression during rolling processes. The characterized plasticity model is implemented into ABAQUS/Explicit as a user-defined material subroutine (VUMAT based on semi-implicit backward Euler's method. The subroutine is employed to simulate square-bar rolling processes. The simulation results are compared with rolled specimens and those predicted by the von Mises and the Hill48 yield function under AFR. Moreover, strip rolling is also simulated for AZ31 with the Hill48 yield function under non-AFR. The strip rolling simulation demonstrates that the lateral spread generated by the non-AFR model is in good agreement with experimental data. These comparisons between simulation and experiments validate that the proposed Hill48 yield function under non-AFR provides satisfactory description of plastic deformation behavior in hot rolling for AZ31 alloys in case that the anisotropic parameters in the Hill48 yield function and the non-associated flow rule are calibrated by the compressive experimental results.

  14. Diffusion Bonding Behavior and Characterization of Joints Made Between 316L Stainless Steel Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Elthalabawy, Waled Mohamed

    The 316L austenitic stainless steel and AZ31 magnesium alloy have physical and mechanical properties which makes these alloys suitable in a number of high technology based industries such as the aerospace and automotive sectors. However, for these alloys to be used in engineering applications, components must be fabricated and joined successfully. The differences in the physical and metallurgical properties between these two alloys prevents the use of conventional fusion welding processes commonly employed in aerospace and transport industry. Therefore, alternative techniques need to be developed and diffusion bonding technology is a process that has considerable potential to join these two dissimilar alloys. In this research work both solid-state and transient liquid phase (TLP) bonding processes were applied. The solid-state bonding of 316L steel to AZ31 magnesium alloy was possible at a bonding temperature of 550°C for 120 minutes using a pressure of 1.3 MPa. The interface characterization of the joint showed a thin intermetallic zone rich in Fe-Al was responsible for providing a metallurgical bond. However, low joint shear strengths were recorded and this was attributed to the poor surface to surface contact. The macro-deformation of the AZ31 alloy prevented the use of higher bonding pressures and longer bonding times. In order to overcome these problems, the TLP bonding process was implemented using pure Cu and Ni foils as interlayers which produced a eutectic phase at the bonding temperature. This research identified the bonding mechanism through microstructural and differential scanning calorimetry investigations. The microstructural characterization of the TLP joints identified intermetallics which became concentrated along the 316L steel/AZ31 bond interface due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The size and concentration of the intermetallics had a noticeable effect on the final joint

  15. 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...

  16. Lap Fillet Welding of Thin Sheet AZ31 Magnesium Alloy with Pulsed Nd:YAG Laser

    Science.gov (United States)

    Ishak, Mahadzir; Yamasaki, Kazuhiko; Maekawa, Katsuhiro

    In recent years, reducing the size and weight of consumer products requires the joining of thin sheets of magnesium alloys with both thickness and joining area of less than 1mm, especially for packaging purposes. Conventional welding processes are difficult to joint a thin sheet magnesium alloy because of high heat input, which in turns leads to various problems such as burn through and cracks. In this study, lap fillet welding of thin sheet magnesium alloy AZ31B with a thickness of 0.3 mm has been carried out using a pulsed Nd:YAG laser beam. The influences of gap, laser beam center location and scan speed on joint appearances have been investigated. It was found that defects were significantly reduced when the gap width was less than 35 µm when the laser beam center was located just on the edge of the upper specimen (x=0), and scan speed was varied from 400 to 450 m/min. Wider bond width at average value of 300 µm was achieved when the beam center was at x=0 with a wide range of scan speeds from 250 to 450 mm/min compared with the cases at x=-0.1 and -0.2 mm from edge. Increases in bond width and minimal defects at x=0 improve fracture load by 68% compared with those at x=-0.1 mm.

  17. Connection of AZ31B Magnesium Alloys and TC4 Titanium Alloy Via Resistance Spot Welding%AZ31B镁合金与TC4钛合金之间的电阻点焊连接

    Institute of Scientific and Technical Information of China (English)

    谈芬芳; 谢志雄; 杜康; 梅张强

    2013-01-01

    In order to make it became realistic that welding of AZ31B magnesium alloys and TC4 titanium alloy via resistance spot welding, in this work the theory of diffusion welding was used. The welding technology of AZ31B magnesium alloys and TC4 titanium alloy aluminum was discussed. In the process, aluminium foil and aluminium powder were used. The property and microstructure of welding spot were analysised by scanning electron microscope (SEM) and X-ray energy dispersion spectroscope (EDS). The results indicate that the mechanical performace of welding sopt is better when aluminiun powder as additive, the diffusion of elements and alloying reaction are conducive to improve the machanical property of welding spot.%为实现AZ31B镁合金与TC4钛合金异种材料的电阻点焊连接,借助扩散焊原理,探讨了在其之间添加铝箔和铝粉的电阻点焊工艺,并对焊点的力学性能及微观结构进行了分析.结果表明,以铝粉作为添加物,可以获得力学性能较好的焊点,元素间的扩散及合金化反应是焊点性能得以提高的主要原因.

  18. 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.

  19. 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.

  20. 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.

  1. Failure observation of the AZ31B magnesium alloy and the effect of lead addition content under ballistic impact

    Directory of Open Access Journals (Sweden)

    Mohamad Faizal Abdullah

    2015-05-01

    Full Text Available The association of the failure behavior of the AZ31B magnesium alloy with absorption energy under ballistic impact condition was investigated in this study, as well as the effect of varying percentages of added lead (Pb content. The compositions of Pb in AZ31B were 1%, 5%, and 10% by percentage weight of Pb. Two types of projectile were used to compare the experimental and simulation results. Ballistic testing on a magnesium alloy plate was performed at the velocity of 435 m/s for the 9 mm×19 mm Parabellum projectile and 976 m/s for the 5.56 mm×45 mm NATO projectile. Simulation was performed using the Johnson–Cook model to determine the maximum stress that the material can withstand. Deformation and failure occurred in the ballistic simulation when the different projectiles were used. In the 9 mm×19 mm Parabellum projectile, no penetration was observed in the magnesium alloy, whereas in the 5.56 mm×45 mm NATO projectile, complete penetration was observed throughout the thickness of the alloy. The addition of Pb on AZ31B affected the absorption energy, and the addition of 1% Pb produced the most suitable absorption energy for further analysis.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Evaluation of self-healing ability of Ce–V conversion coating on AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Xiao Jiang

    2016-09-01

    Full Text Available This study investigated the influence of cerium nitrate in vanadate solutions on the properties of Ce–V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce–V conversion coating for AZ31 magnesium alloy. The results showed that the additions of cerium nitrate prevented pentavalent vanadium from reducing to tetravalent vanadium in the coatings during conversion reaction process. Adding appropriate cerium nitrate to vanadate solution led to a thicker coating with a more compact CeVO4 layer. The corrosion behavior of the Ce–V conversion coating was investigated by the electrochemical tests and the scratch immersion test in 3.5 wt.% NaCl solution. The self-healing ability of the coating was confirmed from all tests. The surface analysis revealed that the self-healing effect of the Ce–V conversion coating was only provided by the release and migration of vanadium compounds.

  8. 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

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Influence of rolling parameters on dynamically recrystallized microstructures in AZ31 magnesium alloy sheets

    Directory of Open Access Journals (Sweden)

    Lili Guo

    2015-06-01

    Full Text Available Conventional rolling experiments via the embedded pin in rolling sheet method were carried out at different reduction rates, starting rolling temperatures, and rolling speeds, and the effects of rolling parameters (i.e., temperature, equivalent strain, and rolling time on dynamically recrystallized (DRX microstructures of AZ31 alloy during hot rolling were studied quantitatively. The temperature-strain dependence of the high-angle grain boundary fraction (HAGB% was examined through electron backscattered diffraction. Results showed that as-rolled microstructures with high HAGB% may be obtained under average rolling temperatures of 270–320 °C, equivalent strains higher than 0.8, and a rolling speed of 246 mm/s. These results may be related to the DRX kinetics and dynamic recovery which are controlled by deformation temperature and strain. HAGB% decreased with increasing rolling time (decreasing rolling speed, which is attributed to dynamic recovery, and the recrystallized grain size decreased as rolling time increased. However, further increases in rolling time increased average grain sizes but decreased mean subgrain sizes; these results are attributed to increases in the low-angle grain boundary (LAGB length per unit area with rolling time. LAGB formation was controlled by dynamic recovery, which consistently follows polygonization or formation of new subgrains inside larger grains; hence, average subgrain sizes decreased with the rolling time. The effect of dynamic recovery on HAGB and LAGB formation and their related mechanisms over a wide range of strains and temperatures were discussed in detail.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 激光重熔处理对AZ31镁合金表面特性的影响%Effects of Laser Cladding Treatment on Surface Performance of AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    卫中山; 刘六法

    2011-01-01

    Effects of laser cladding treatment on surface performance of AZ31 magnesium alloy sheet were observed by the help of Nd-YAG laser. Rapid melting-solidification occurs on the surface of the AZ31 magnesium alloy sheet, and treated surface is composed of re-melting zone and heat history zone.Grain size is apparently refined in the re-melting zone, and hardness is increased by 5 % compared to that of the matrix. Immersing corrosion experiment shows that corrosion resistance of AZ31 magnesium alloy with laser cladding treatment is greatly improved in 3.5 % NaC1 solution, which is attributed to grain refinement in re-melting zone and enrichment of Al element in cladding surface.%使用Nd-YAG激光器对AZ31镁合金板材表面进行了激光重熔处理,分析了激光重熔处理对其表面特性的影响.在激光扫描时,试样表面发生了快速熔凝,处理层可分为重熔区、热影响区两部分.重熔区的晶粒得到明显细化,硬度比基体提高5%.腐蚀试验表明,AZ31镁合金在激光重熔处理后,在3.5%的NaCl溶液中的耐蚀性得到明显改善.重熔区晶粒细化和Al元素富集是激光重熔表面处理提高其耐蚀性的主要因素.

  1. 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.

  2. Residual Stresses and Tensile Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy in Lap Configuration

    Science.gov (United States)

    Naik, Bhukya Srinivasa; Cao, Xinjin; Wanjara, Priti; Friedman, Jacob; Chen, Daolun

    2015-08-01

    AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir welded in lap configuration using two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The residual stresses in the longitudinal and transverse directions of the weldments were determined using X-ray diffraction. The shear tensile behavior of the lap joints was evaluated at low [233 K (-40 °C)], room [298 K (25 °C)], and elevated [453 K (180 °C)] temperatures. The failure load was highest for the lower heat input condition that was obtained at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s for all the test temperatures, due to the smaller hooking height, larger effective sheet thickness, and lower tensile residual stresses, as compared to the other two welding conditions that were conducted at a higher tool rotational rate or lower welding speed. The lap joints usually fractured on the advancing side of the top sheet near the interface between the thermo-mechanically affected zone and the stir zone. Elevated temperature testing of the weld assembled at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s led to the failure along the sheet interface in shear fracture mode due to the high integrity of the joint that exhibited large plastic deformation and higher total energy absorption.

  3. Incremental forming of free surface with magnesium alloy AZ31 sheet at warm temperatures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The formability of AZ31 sheet begins to increase drastically at 150 ℃. The incremental forming technique was thus applied to AZ31 sheet at 150 ℃ to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications. A surface scanning technique was used followed by the tool path generation to incrementally form an egg surface. After thorough examination of various tool paths, the surface was most successfully produced by forming an intermediate shape followed by a series of tool paths. Flexible scale stickers were devised to improve the accuracy in the measurement of grid deformation.

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. 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.

  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. 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.

  11. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Science.gov (United States)

    Li, Kun; Liu, Junyao; Lei, Ting; Xiao, Tao

    2015-10-01

    A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  12. 渗注锆酸盐对AZ31镁合金疲劳裂纹扩展速率的影响%Effects of the Zirconate Deposition on Fatigue Crack Growth Rate in AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    贺显聪; 王章忠; 白允强; 巴志新; 周衡志; 沈鸿烈

    2011-01-01

    The zirconate deposition behavior and effects of the zirconate on fatigue crack growth rate at the fatigue crack tip of AZ31 magnesium alloy under alternate loads were investigated. The morphology and components of the zirconate deposition at the fatigue crack tip were characterized by means of scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD), respectively. The stress intensity factors at the fatigue crack tips with and without zirconate deposition were measured by taking advantage of strain gauge. The results show that the zirconate (ZrxOy ZnxOy) films can be formed at the fatigue crack tips of AZ31 magnesium alloy. The stress intensity factor value is decreased about 40%, which effectively yields fatigue crack closure, reduce or even vanishes the fatigue crack growth rate.%研究交变载荷作用下,在AZ31镁合金疲劳裂纹尖端渗注锆酸盐的沉积行为及其对疲劳裂纹扩展速率的影响.用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD)观察分析裂纹尖端的形貌和物相成分,采取贴应变片方法确定渗注锆酸盐前后应力强度因子的变化.结果表明:锆酸盐转化液能在AZ31镁合金疲劳裂纹尖端形成锆酸盐ZrxOyZnxOy覆层;渗注锆酸盐后裂纹尖端应力强度因子降低约40%,能有效增强疲劳裂纹闭合效应,降低或延滞其疲劳裂纹扩展速率.

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. The Effect of SiC Particle Addition During FSW on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy

    Science.gov (United States)

    Abbasi, M.; Abdollahzadeh, A.; Bagheri, B.; Omidvar, H.

    2015-12-01

    Welding and joining of magnesium alloys exert a profound effect on magnesium application expansion, especially in ground and air transportations where large-size, complex components are required. Due to specific physical properties of magnesium, its welding requires great control. In general, the solid-state nature of friction stir welding (FSW) process has been found to produce a low concentration of defects. In the current research, specimens from AZ31 magnesium alloy were welded together using the friction stir process with previously inserted SiC powder particles in the nugget zone. In other words, during the FSW process, the pre-placed SiC particles were stirred throughout the nugget zone of the weld. The results indicated that proper values of rotation and translation speeds led to good appearance of weld zone and suitable distribution of SiC particles producing increased weld strength. The comparison of the microstructures and mechanical properties of FS-welded AZ31 with those of FS-welded one using pre-placed SiC particles showed that the addition of SiC particles decreased the grain size and increased the strength and the formability index.

  19. 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.

  20. Effect of heat input on microstructure and properties of welded joint in magnesium alloy AZ31B

    Institute of Scientific and Technical Information of China (English)

    刘黎明; 苗玉刚; 宋刚; 梁国俐

    2004-01-01

    Using the optical microscope, tensile test machine and micro-hardness meter, the effect of heat input on the microstructure and mechanical properties in fusion welding joints of AZ31B wrought alloys was investigated systematically, the mechanism on joint properties losing was analyzed, and a valid method to improve joint properties of the magnesium alloy fusion welding was explored. The results show that the heat input has an obvious effect on the microstructure and properties. Under the condition of penetration, with the heat input decreasing, the crystal grain in the weld and heat-affected zone (HAZ) becomes fine, the width of HAZ becomes obviously narrow, and the molding of the weld is improved, so the tensile strength and elongation are increased and the hardness of joints is improved. When the heat input reaches 60 J/mm, the high quality joints can be gained.

  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. Friction Stir Welding Effect on Transverse Rigidity and Sound Transmission Characteristics of AZ31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Luo Zhi; Hao Zhiyong; Ni Dingrui; Zheng Xu

    2015-01-01

    AZ31B magnesium alloy was subjected to friction stir welding withvarious welding parameters. The equivalent Young’s moduli of the friction stir welded samples and the base material were obtained by the three-point method, and their transverse rigidities were obtained as well. Furthermore, the sound transmission characteristics of those samples were experimentally studied by four-microphone impedance tube method. The experimental results indicate that the transverse rigidities of the friction stir welded samples were only 79%, 83% and 92% of thoseof the base material, respectively. The sound transmission losses of the processed samples were also lower, which was largely due to the reduction of transverse rigidities induced by the decrease of equivalent Young’s moduli.

  5. Effect of welding speed on the material flow patterns in friction stir welding of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; Wu Huiqiang; Huang Jihua; LIN Sanbao; WU Lin

    2007-01-01

    The clear zigzag-line pattern on transverse cross sections can be used to explain the formation mechanism of the weld nugget when friction stir welded AZ31 magnesium alloy without any other insert material is used as mark. It provides a simple and useful method to research the joining mechanism of friction stir welding. The rotation speed is kept at 1000 r/min and the welding speed changes from 120 mm/min to 600 mm/min. The macrostructure on the transverse cross section was divided into several parts by faying surface. The results show that the shape and formation procedure of the weld nugget change with the welding speed. There are two main material flows in the weld nugget: one is from the advancing side and the other is from the retreating side. A simple model on the weld nugget formation of FSW is presented in this article.

  6. 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

  7. 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.

  8. 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.

  9. Microstructural evolution characterization of friction stirring welded AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; LIN Sanbao; WU Lin; FENG Jicai

    2004-01-01

    A friction stirring welding to joint 5 mm rolled AZ31 magnesium had been developed. The microstructures in various regions including the weld nugget, thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ) were investigated and compared with unaffected parent metal using optical microscopy. The results showed that the heat and mechanical process had great effect on the microstructure evolution. In weld nugget, the heat was enough to produce sufficient superplastic material flow and the mechanical effect was greatest, and the dynamic recrystallization was completed thoroughly. In TMAZ, the mechanical effect was indirectly affected by the welding tool and only some grains had undergone dynamic recrystallization. The various regions were studied in detail to better understand the microstructural evolution during friction stirring welding (FSW). The cross section near the "key hole" showed clear onion rings because the material was stirred only by the rotation of the probe and materials rotated with the probe and did not move along welding direction and in vertical direction, there was no material flow and the flow movement can be regarded as two dimensional layer flow.

  10. 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

  11. Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Tulia Espinosa

    2015-01-01

    Full Text Available Surface coatings formed by immersion in the ionic liquids (ILs 1,3-dimethylimidazolium methylphosphonate (LMP101, 1-ethyl-3-methylimidazolium methylphosphonate (LMP102 and 1-ethyl-3-methylimidazolium ethylphosphonate (LEP102 on magnesium alloy AZ31B at 50 °C have been studied. The purpose of increasing the temperature was to reduce the immersion time, from 14 days at room temperature, to 48 hours at 50 °C. The abrasion resistance of the coated alloy was studied by microscratching under progressively increasing load, and compared with that of the uncoated material. The order of abrasion resistance as a function of the IL is LEP102 > LMP101 > LMP102, which is in agreement with the order obtained for the coatings grown at room temperature. The maximum reduction in penetration depth with respect to the uncovered alloy, of a 44.5%, is obtained for the sample treated with the ethylphosphonate LEP102. However, this reduction is lower than that obtained when the coating is grown at room temperature. This is attributed to the increased thickness and lower adhesion of the coatings obtained at 50 °C, particularly those obtained from methylphosphonate ionic liquids. The results are discussed from SEM-EDX and profilometry.

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. AZ31变形镁合金化学镀前无铬酸洗工艺研究%An Investigation of Chromium-Free Pickling Process for Electroless Nickel Plating on AZ 31 Wrought Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    秦铁男; 马立群; 贺忠臣; 姚妍; 丁毅

    2011-01-01

    主要研究了AZ 31变形镁合金化学镀前的磷酸-硝酸-氢氟酸混合酸洗工艺及各组分对镁合金基体的腐蚀失重表面形貌、镀层与基体的截面形貌和结合力的影响.结果表明:氢氟酸的加入可以有效降低酸洗反应速率并防止新鲜的镁合金基体表面的再次氧化;硝酸的体积分数对镁合金表面形貌的改变有较大影响;当磷酸-硝酸-氢氟酸的体积分数分别为300 mL/L,60 mL/L和100 mL/L时,镀层与基体的结合力最好.%A phosphoric acid-nitric acid-hydrofuoric acid mixed acid pickling process was studied for electroless nickel plating on AZ 31 wrought magnesium alloy sheet. The effects of pickle components on corrosion weight loss, surface morphology, cross section morphology and adhesion strength between the substrate and coating were investigated. The results show that addition of hydrofluoric acid can effectively reduce the rate of pickling reaction and protect the fresh substrate from being Oxidized again. The volume fraction of nitric acid has a great impact on changes of the surface morphology of magnesium substrate. The best adhesion strength between the substrate and the coating is achieved when the pickle solution contains 300 mL/L phosphoric acid, 60 mL/L nitric acid and 100 mL/L hydrofluoric acid.

  17. Numerical and experimental evaluation of Nd:YAG laser welding efficiency in AZ31 magnesium alloy butt joints

    Science.gov (United States)

    Scintilla, Leonardo Daniele; Tricarico, Luigi

    2013-02-01

    In this paper, energy aspects related to the efficiency of laser welding process using a 2 kW Nd:YAG laser were investigated and reported. AZ31B magnesium alloy sheets 3.3 mm thick were butt-welded without filler using Helium and Argon as shielding gases. A three-dimensional and semi-stationary finite element model was developed to evaluate the effect of laser power and welding speed on the absorption coefficient, the melting and welding efficiencies. The modeled volumetric heat source took into account a scale factor, and the shape factors given by the attenuation of the beam within the workpiece and the beam intensity distribution. The numerical model was calibrated using experimental data on the basis of morphological parameters of the weld bead. Results revealed a good correspondence between experiment and simulation analysis of the energy aspects of welding. Considering results of mechanical characterization of butt joints previously obtained, the optimization of welding condition in terms of mechanical properties and energy parameters was performed. The best condition is represented by the lower laser power and higher welding speed that corresponds to the lower heat input given to the joint.

  18. Dependence of deformation mechanisms on grain orientations and their changes calculated based on Sachs model in magnesium alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    Qing-ge XIE; Ping YANG; Li MENG

    2008-01-01

    During deformation, the orientation of a grain influences not only the deformation mechanisms (slip or twinning) and the specific selection of activated slip or twinning systems for that grain, but also the kinetics of different types of transformation. Schmid factor analysis was applied to determine the orientation dependency of deformation mechanisms in magnesium alloys AZ31 in this work. The orientation changes after the operation of the specific deformation mechanisms were also calcu-lated based on Sachs model. It was found that different deformation mechanisms proceeded differently according to theoretical predictions. Basal slip occurred when basal planes of grains were tilted toward ND around TD. Prismatic slip dominated when basal planes were approxi-mately perpendicular to TD. Calculation results also indi-cated that the operating of pyramidal slip can not be neglected. {10 12} twinning was favorable when basal planes were approximately normal to RD and { 10 11 } twinning was analyzed to be related to the grains with basal orientations. The operating of slip could greatly suppress the activating of twinning by our Schmid factor analysis. Basal orientations with TD and RD scattering can favor basal slip and tension twinning, respectively, after the operation of compression twinning based on the Schmid factor calculations.

  19. The Effect of Short Duration Electric Current on the Quasi-Static Tensile Behavior of Magnesium AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Trung Thien Nguyen

    2016-01-01

    Full Text Available The effect of a single pulse of electric current with short duration on the quasi-static tensile behavior of a magnesium AZ31 alloy is experimentally investigated. A single pulse of electric current with duration less than 1 second is applied to the specimen, while the specimen is being deformed in the plastic region under quasi-static tensile loads. After a nearly instant decrease of flow stress at the pulse of electric current, the flow stress shows strain hardening until the failure of the specimen. The experimental result shows that the strain-hardening parameters (the strength coefficient and the strain-hardening exponent of the hardening curve after the electric current strongly depend on the applied electric energy density (electric energy per unit volume. Empirical expressions are suggested to describe the hardening behavior after the pulse as a function of the electric energy density and are compared with the empirical expressions suggested for advanced high-strength steels.

  20. 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.

  1. AZ31镁合金激光焊件的力学性能和应力腐蚀行为%Mechanical properties and stress corrosion cracking behaviour of AZ31 magnesium alloy laser weldments

    Institute of Scientific and Technical Information of China (English)

    P. B. SRINIVASAN; S. RIEKEHR; C. BLAWERT; W. DIETZEL; M. KO(C)AK

    2011-01-01

    采用Nd-YAG激光对AZ31 HP镁合金进行激光自熔焊接.显微组织分析表明,使用或不使用填料(焊料)AZ61镁合金得到的激光焊接接头的平均晶粒尺寸大约为12 μm,显微硬度和拉伸强度与母材相近.然而,慢应变速率拉伸表明,在ASTM D1384溶液中两种焊接接头的抗应力腐蚀性能比母材略差.可观察到应力腐蚀裂纹在焊缝金属萌生并向热影响区(HAZ)扩展.然而,在以AZ61镁合金为填料(焊料)获得的焊接接头中,观察到裂纹起源及扩展出现在热影响区(HAZ).在慢应变速率拉伸试验中,由于试样表面暴露在腐蚀环境中,在氢氧化镁/氧化镁层形成局部损伤,从而导致应力腐蚀裂纹的生成.%An AZ31 HP magnesium alloy was laser beam welded in autogenous mode with AZ61 filler using Nd-YAG laser system. Microstructural examination revealed that the laser beam weld metals obtained with or without filler material had an average grain size of about 12 μm. The microhardness and the tensile strength of the weldments were similar to those of the parent alloy. However, the stress corrosion cracking (SCC) behaviour of both the weldments assessed by slow strain rate tensile (SSRT) tests in ASTM D1384 solution was found to be slightly inferior to that of the parent alloy. It was observed that the stress corrosion cracks originated in the weld metal and propagated through the weld metal-HAZ regions in the autogenous weldment. On the other hand, in the weldment obtained with AZ61 filler material, the crack initiation and propagation was in the HAZ region. The localized damage of the magnesium hydroxide/oxide film formed on the surface of the specimens due to the exposure to the corrosive environment during the SSRT tests was found to be responsible for the SCC.

  2. Crystal plasticity simulation on earing during deep drawing of AZ31 magnesium alloy%AZ31镁合金板材冲压成形制耳的晶体塑性模拟

    Institute of Scientific and Technical Information of China (English)

    唐伟琴; 李大永; 彭颖红

    2014-01-01

    In order to predict the earing behavior during deep drawing of magnesium alloy accurately, a crystal plasticity theory combined with finite element method was proposed. First of all, based on the microscopic nature of plastic deformation during warm forming, a crystal plasticity constitutive model coupling slip and twinning was established for magnesium alloy with hexagonal close packed (HCP) structure. Then, in order to establish crystal plasticity finite element model for large deformation, the secondary development interface (VUMAT) of the commercial finite element software ABAQUS/Explicit and Fortran programming language were used, the deformation modes and model parameters were determined by combining the theory, simulation and experiments. Finally, the commercial rolled AZ31 magnesium alloy sheets were simulated during deep cup drawing using the HCP crystal plasticity finite element model, and the predicting method is validated by comparing with experimental results from both earing profile and deformation texture. Both the experimental and simulated results show significant earings at 45° away from rolling direction and texture components of (0001) 〉〈10 1 0 and tensile twinning.%针对AZ31镁合金板材深冲过程中的制耳现象,提出一种基于晶体塑性理论的镁合金板材冲压制耳行为的预测方法。首先,从镁合金温成形时的塑性变形机理(即滑移和孪生共同作用)出发,建立耦合滑移和孪生的适合密排六方结构(HCP)金属的晶体塑性本构模型;在此基础上,编制相关程序,通过结合理论、模拟和实验的方法确定镁板微观变形机制组合和多晶体模型参数两个关键因素,构建了适用于镁合金板材大变形的晶体塑性有限元仿真模型;最后,采用HCP板材大变形晶体塑性有限元模型对AZ31镁合金板材的杯形件冲压过程进行有限元仿真,并利用实验结果从制耳轮廓和变形织构两方面验证 HCP 晶

  3. 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).

  4. Plasticity and microstructure of AZ31 magnesium alloy under coupling action of high pulsed magnetic field and external stress%强磁与应力场耦合作用下AZ31镁合金塑性变形行为∗

    Institute of Scientific and Technical Information of China (English)

    王宏明; 朱弋; 李桂荣; 郑瑞

    2016-01-01

    As an h.c.p crystal structure with only a few limited slipping planes, the AZ31 magnesium alloy exhibits a bad plasticity in the presence of external stress. Due to its low density, advanced damping capacity and high ratio strength and rigidity, the magnesium alloy has gradually become the focused and potential structural and functional metallic material in the diverse fields of aerospace, aviation and vehicle transportation, electronic products, etc. Therefore, it is of great importance to improve the process ability of conventional magnetism alloy as AZ31. In the past decades many approaches have been proposed in order to improve the plastic deformation capability. Among these, the diverse physical fields are regarded as the effective methods to improve the comprehensive mechanical properties of metallic materials due to their peculiar heat, force and quantum effects together with the advantageous characteristics of low pollution and high efficiency. In the paper, on the basis of previous researches, a high pulsed magnetic field is introduced into the tensile test to study the influences of magnetic field on the plasticity and microstructure of AZ31 magnesium alloy in order to explore a novel way to enhance the plastic deformation capability of alloy. As for the current experiment, the tensile test of AZ31 magnesium alloy is carried out under the coupling action of high pulsed magnetic field and external stress. The test results are compared with those processed without magnetic field. Several advanced detection methods are utilized to investigate the microstructure including the electron back scattered diffraction, X-ray diffraction and transmission electron microscopy, etc. Besides, the first principle is utilized to calculate the magnetic properties of main precipitatesβ(Mg17Al12). The experimental results show that the tensile strength and elongation of the 3 T sample are increased by 2.2%and 28.7%in comparison to those of the 0 T sample. It highlights that

  5. 低能量密度气体激光熔凝AZ31B镁合金的微观组织与磨损性能%Microstructure and Wear Resistance of Low Energy Density Gas Laser Surface Melting on AZ31B Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    葛亚琼; 郭谡; 王鑫; 王文先; 李想

    2012-01-01

    In order to improve the wear resistance of AZ31B magnesium alloy, laser melted layer which had no crack and hole on AZ31B magnesium substrate was created by a 5 kW continuous wave CO2 laser with low density energy. The macrostructure, microstructure and phases were analyzed by means of optical microscope and X-ray Diffraction, the microhardness and abrasion performance were also tested with microhardness tester and abrasion testing instrument. The results showed that, the melted layers were mainly consisted of α-Mg and β-Mgl7A112, and the grains of melted layer were smaller than that of base metal. With the technique of lower energy density laser which was P=2 kW, v= 15 mm/s, £=26 J/mm2, the strengthening effect of fine-grain and β-Mgl7A112 was the best, the microhardness of laser melted layer was 50 HV0.05~79 HV0.05 which was improved by 13.64% ~ 64.58% and wear resistance was improved by 60% as compared to as-received AZ31B, the wear mass loss was 40% of as-received AZ31B. These showed that, the best laser melted layer with the best microhardness and wear resistance could be obtained by the technique of low density laser energy with high laser power and fast velocity.%为提高镁合金表面的耐磨性,利用5 kW横流连续C02激光器在AZ31B镁合金表面采用低能量密度激光能量制备了无裂纹、气孔等缺陷的熔凝层.通过光学显微镜、X射线衍射仪观察分析熔覆层的宏观形貌、微观组织和物相,并利用显微硬度仪、磨损试验机测试熔覆层的显微硬度和耐磨性.研究结果表明:熔覆层由α-Mg和β-Mgl7Al12组成,晶粒明显细化.采用低能量密度工艺即激光功率P=2 kW、扫描速度v=15 mm/s、激光能量密度E=26 J/mm2时,晶粒细化程度和β-Mg17Al12强化相综合强化效果最好,即显微硬度最高,为50 HV0.05~79 HV0.05比基体提高了13.64%~64.58%;耐磨性改善程度最好,磨损量是原始镁合金的40%,耐磨性提高60%.说明采用低能量

  6. Formation of a Spinel Coating on AZ31 Magnesium Alloy by Plasma Electrolytic Oxidation

    Science.gov (United States)

    Sieber, Maximilian; Simchen, Frank; Scharf, Ingolf; Lampke, Thomas

    2016-03-01

    Plasma electrolytic oxidation (PEO) is a common means for the surface modification of light metals. However, PEO of magnesium substrates in dilute electrolytes generally leads to the formation of coatings consisting of unfavorable MgO magnesium oxide. By incorporation of electrolyte components, the phase constitution of the oxide coatings can be modified. Coatings consisting exclusively of MgAl2O4 magnesium-aluminum spinel are produced by PEO in an electrolyte containing hydroxide, aluminate, and phosphate anions. The hardness of the coatings is 3.5 GPa on Martens scale on average. Compared to the bare substrate, the coatings reduce the corrosion current density in dilute sodium chloride solution by approx. one order of magnitude and slightly shift the corrosion potential toward more noble values.

  7. 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.

  8. 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

  9. 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.

  10. AZ31B镁合金/不锈钢异种合金双光束激光熔钎焊接特性%Welding Characteristics of AZ31B Magnesium Alloy/Stainless Steel Dissimilar Alloys by Dual Beam Laser Welding-Brazing Process

    Institute of Scientific and Technical Information of China (English)

    李俐群; 郭伟; 檀财旺

    2012-01-01

    以镁基焊丝为填充材料,采用双光束激光熔钎焊的方法对AZ31B镁合金/不锈钢的焊接特性进行了研究.分析了不同工艺参数对焊缝成形、接头力学性能和断裂行为的影响.结果表明,采用双光束进行填丝熔钎焊能够获得较满意的外观成形,无明显缺陷,焊接工艺范围较宽.接头拉伸均断裂于熔化焊的镁侧焊缝及热影响区(HAZ),最大剪切强度为193 MPa,达到镁合金母材强度的71%.组织分析发现焊缝和HAZ的晶粒粗大,成为接头的薄弱部位,是接头失效的主要原因.钎焊侧界面发生了冶金反应,界面处生成1~2 μm的反应层.%AZ31B magnesium alloys and 201 stainless steel are joined by laser welding-brazing process with Mg based filler. The welding characteristics including influence of processing parameters on weld appearance, mechanical properties and fracture behavior are studied- Results indicate that satisfactory appearance of welds without evident defects can be achieved by dual beam laser-brazing process with filler. A wide processing window is obtained. The tensile-shear test shows that fracture occurred at two places, weld seam and heat affect zone (HAZ) at the welding side of Mg alloys. The maximum shear strength can reach 193 Mpa, which is 71% of that of Mg base metal. The microstructure observed indicates that seam and HAZ are weak parts, which results in failure of joint due to presence of coarse grains. Metallurgical reaction occurs at the brazing side, where reaction layer with thickness of 1~2 μm forms.

  11. Enhancement of the mechanical properties of AZ31 magnesium alloy via nanostructured hydroxyapatite thin films fabricated via radio-frequency magnetron sputtering.

    Science.gov (United States)

    Surmeneva, M A; Tyurin, A I; Mukhametkaliyev, T M; Pirozhkova, T S; Shuvarin, I A; Syrtanov, M S; Surmenev, R A

    2015-06-01

    The structure, composition and morphology of a radio-frequency (RF) magnetron sputter-deposited dense nano-hydroxyapatite (HA) coating that was deposited on the surface of an AZ31 magnesium alloy were characterized using AFM, SEM, EDX and XRD. The results obtained from SEM and XRD experiments revealed that the bias applied during the deposition of the HA coating resulted in a decrease in the grain and crystallite size of the film having a crucial role in enhancing the mechanical properties of the fabricated biocomposites. A maximum hardness of 9.04 GPa was found for the HA coating, which was prepared using a bias of -50 V. The hardness of the HA film deposited on the grounded substrate (GS) was found to be 4.9 GPa. The elastic strain to failure (H/E) and the plastic deformation resistance (H(3)/E(2)) for an indentation depth of 50 nm for the HA coating fabricated at a bias of -50 V was found to increase by ~30% and ~74%, respectively, compared with the coating deposited at the GS holder. The nanoindentation tests demonstrated that all of the HA coatings increased the surface hardness on both the microscale and the nanoscale. Therefore, the results revealed that the films deposited on the surface of the AZ31 magnesium alloy at a negative substrate bias can significantly enhance the wear resistance of this resorbable alloy.

  12. 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.

  13. Effect of Ar bubbling during plasma electrolytic oxidation of AZ31B magnesium alloy in silicate electrolyte

    Science.gov (United States)

    Lee, Junghoon; Kim, Yonghwan; Chung, Wonsub

    2012-10-01

    Argon gas was bubbled during plasma electrolytic oxidation (PEO) treatment of magnesium alloy in a silicate solution. The appearance of arcs and plasma discharging was locally concentrated on the magnesium alloy surface and phase fraction of Mg2SiO4 in the oxide layer was increased due to Argon gas bubbling. The higher energy density of the Ar plasma atmosphere is believed to contribute to the effective formation of the high temperature phase (Mg2SiO4), particularly in the inner layer. Furthermore, the PEO treated Mg alloy with Ar bubbling showed improved corrosion resistance by a change of open pores structure.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Effect of biologically relevant ions on the corrosion products formed on alloy AZ31B: an improved understanding of magnesium corrosion.

    Science.gov (United States)

    Jang, Yongseok; Collins, Boyce; Sankar, Jagannathan; Yun, Yeoheung

    2013-11-01

    Simulated physiological solutions mimicking human plasma have been utilized to study the in vitro corrosion of biodegradable metals. However, corrosion and corrosion product formation are different for different solutions with varied responses and, hence, the prediction of in vivo degradation behavior is not feasible based on these studies alone. This paper reports the role of physiologically relevant salts and their concentrations on the corrosion behavior of a magnesium alloy (AZ31B) and subsequent corrosion production formation. Immersion tests were performed for three different concentrations of Ca(2+), HPO4(2-), HCO3(-) to identify the effect of each ion on the corrosion of AZ31B assessed at 1, 3 and 10 days. Time-lapse morphological characterization of the samples was performed using X-ray computed tomography and scanning electron microscopy. The chemical composition of the surface corrosion products was determined by electron dispersive X-ray spectroscopy and X-ray diffraction. The results show that: (1) calcium is not present in the corrosion product layer when only Cl(-) and OH(-) anions are available; (2) the presence of phosphate induces formation of a densely packed amorphous magnesium phosphate corrosion product layer when HPO4(2-) and Cl(-) are present in solution; (3) octacalcium phosphate and hydroxyapatite (HAp) are deposited on the surface of the magnesium alloy when HPO4(2-) and Ca(2+) are present together in NaCl solution (this coating limits localized corrosion and increases general corrosion resistance); (4) addition of HCO3(-) accelerates the overall corrosion rate, which increases with increasing bicarbonate concentration; (5) the corrosion rate decreases due to the formation of insoluble HAp on the surface when HCO3(-), Ca(2+), and HPO4(2-) are present together.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.)

  8. Influence of temperature and strain rate on flow stress behavior of twin-roll cast, rolled and heat-treated AZ31 magnesium alloys%温度和应变速率对双辊铸轧、轧制和热处理态AZ31镁合金流动应力行为的影响

    Institute of Scientific and Technical Information of China (English)

    F BERGE; L KRGER; H OUAZIZ; C ULLRICH

    2015-01-01

    The effects of temperature and strain rate on the flow stress behavior of twin-roll cast, rolled and heat-treated AZ31 magnesium alloys were investigated under uniaxial tension. At high temperatures, dynamic recovery, continuous dynamic recrystallization, grain boundary sliding and the activation of additional slip systems lead to an improvement of the ductility of the alloys. The elongation to failure is nearly independent of the strain rate between 473 and 523 K at 10−2 s−1 and 10−1 s−1, which is related to the strain rate dependence of the critical resolved shear stress (CRSS) for nonbasal slip. Despite the high temperature, twins are even observed at 573 K and 10−3 s−1 because they have a low CRSS.%在单轴拉伸条件下研究温度和应变速率对双辊铸轧、轧制和热处理AZ31镁合金流动应力行为的影响。结果表明,在高温下,动态回复、连续动态再结晶、晶界滑移和附加滑移系的活化使合金的延展得到改善。在473~523 K和10−2~10−1 s−1条件下,合金的断裂伸长率几乎与应变速率无关,而与应变速率依赖于临界剪切应的非基面滑移有关。由于经上述工艺加工的AZ31镁合金具有较低的临界剪切应力,因此在573 K和10−3 s−1条件下出现了孪晶。

  9. 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.

  10. 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, ...

  11. 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.

  12. 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.

  13. AZ31镁合金单轴拉伸过程中的{0002}双峰织构观察%{0002}Double Peak Texture of AZ31 Magnesium Alloy during Uniaxial Tension

    Institute of Scientific and Technical Information of China (English)

    孟强; 蔡庆伍; 江海涛; 胡水平

    2011-01-01

    The microtopography, microtexture, macrotexture and mechanical properties of A231 magnesium extruaion sheet after different amount of tendsile strain were investigated using optical microscope ( OM) , scanning electron microscopy ( SEM) coupled witb electron back-scatter diffraction ( EBSD) , X-ray diffractometer ( XRD) and tensile test machine.The results showed that, in the early stage of tensile deformation (e = 0.002) , a large quantity of twins generated in A231 magnesium extrusion sheel and showed a banded distribution, the band perpendicular to tensile direction, and the number of twins increased conuistently in the whole tension proces.EBSD analysi, indicated that twins generated in the early deformation stage were c-axis tension-type, twinning orientation exhibited a double peak in [ 0002] pole figure, the tilted direction perpendicular to the tensile direction and the rotate angle was about ±20°~ 30°.The [0002] macrotexture intenaity undulately rose with the increase of tenaile atrain, eventually formed a double peak type, the tilied direction and rotate angle were consistent well with tension twins double peak texture which observed by EBSD, thus twinning might be one of important reasons for [ 0002] macrotexture exhibited double peak.Owing to large quantity of tensile twins Senerated in [ 1l-20] oriented graina and twin boundaries counteracted dialocation, the tensile sample exhibited a low yield 8trength and high n value; there were 50 MPa and 0.56 re8pectively.%采用光学显微镜(OM)、扫描电镜(SEM)结合电子背散射衍射(EBSD)、X射线衍射仪(XRD)及拉伸试验机对不同拉伸应变量下A731镁合金挤压板的显微组织、微观织构、宏观织构及力学性能进行了观察.结果表明:在拉伸变形初期(ε=0.002),AZ31镁合金挤压板中就生成了大量呈条带状分布的孪晶,条带走向与拉伸方向垂直,在整个拉伸过程中孪晶数最持续增加.EBSD微观取向分析结

  14. Effect of laser shock times on electrochemical performance of AZ31 magnesium alloy%激光冲击次数对镁合金电化学特性的影响

    Institute of Scientific and Technical Information of China (English)

    李兴成; 张永康

    2015-01-01

    为了研究激光冲击对镁合金表面抗腐蚀性能的影响,利用钕玻璃脉冲激光对AZ31镁合金表面进行不同次数的激光冲击处理,用透射电子显微镜观察镁合金表层的微观组织,并采用电化学测量技术在氯化钠溶液(质量分数为0.035)中测试其极化曲线和电化学交流阻抗谱的影响。结果表明,激光冲击波导致镁合金表面层产生超高应变速率的塑性变形;晶粒内部存在与孪晶相互交叉、相互缠结的高密度位错而导致晶粒细化;极化曲线和交流阻抗谱表明1次激光冲击后AZ31的自腐蚀电位提高约267mV;腐蚀电流稍有增大,反应电阻增大,抗腐蚀性明显提高;随着冲击次数的增多,腐蚀抗力未明显提高。其相应的交流阻抗谱也得出与极化曲线相同的结论。该研究对于激光冲击处理镁合金提高耐腐蚀性具有一定的参考价值。%In order to study effect of laser shock times on corrosion resistance of AZ 31 magnesium alloy , AZ31 magnesium alloy was processed at different laser shock process ( LSP) times by Nd∶glass laser with pulse width of 23ns. Microstructures were observed by transmission electron microscopy .Polarization curves and electrochemical impedance spectroscopy were obtained in NaCl solution with 0.035 mass fraction by means of electrochemical measurement technique . The results show that plastic deformation with ultrahigh strain rate happens because of laser shock wave at the surface layer of AZ31 magnesium alloy .High density dislocations with intersect and entanglement of twin crystal exist in the crystal grains and the dislocations led to grain refinement .Polarization curves and electrochemical impedance spectroscopy shows that corrosion potential of AZ31 increases up to 267mV after the first laser shock.Corrosion current increases slightly , reaction resistance increases and corrosion resistance is improved significantly .With the increase of

  15. 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.

  16. 极端冷却条件下AZ31B镁合金激光熔凝层的组织与性能%Microstructure and Properties of Laser Melted Layer of AZ31B Magnesium Alloy at Extreme Cooling Condition

    Institute of Scientific and Technical Information of China (English)

    王文先; 陈建华; 张红霞; 崔泽琴; 闫兴贵

    2011-01-01

    Surface of AZ31B magnesium alloy is melted using a pulsed Nd: YAG laser in liquid nitrogen. Then the laser melted layer cooled in liquid nitrogen is compared with that cooled in air and the substrate. The results show that the grain size of the laser melted layer cooled in liquid nitrogen is smaller than that cooled in air. The laser melted layer cooled in liquid nitrogen has higher micro-hardness (70~77 HV005) than that cooled in air(60~ 67 HV0.05) compared with the as-received magnesium alloy (about 55 Hvo.os) ■ The wear mass loss of the laser melted layer cooled in liquid nitrogen (1X 10~3 g) is less than that cooled in air (2 X 10'3 g). The results indicate that liquid nitrogen is better for the enhancement of wear resistance of the laser melted layer. The experimental results show that the corrosion potential of the laser melted layer cooled in liquid nitrogen and cooled in air decrease by 22 mV and 29 mV than those of the as-received magnesium alloy respectively. This indicates that corrosion resistance of AZ31B magnesium alloys becomes worse by laser surface melting.%采用固体脉冲Nd:YAG激光器,对AZ31 B镁合金进行了液氮极端冷却条件下的表面熔凝试验,并与在空气中冷却的熔凝层和原始镁合金进行了对比.结果表明,液氮冷却熔凝层的晶粒比空气冷却熔凝层晶粒更加细小.液氮冷却熔凝层的显微硬度达到70-77 HV0.05,明显高于原始镁合金的显微硬度(约55 H V0.05),且高于空气冷却熔凝层的60-67 HV0.05.磨损试验表明,液氮冷却熔凝层的磨损量为1×10-3 g,小于空气冷却熔凝层的2×10-3 g,说明液氮冷却条件更有利于镁合金表面耐磨性能的提高.在质量分数为3.5%的NaCl溶液中的电化学极化曲线测试结果表明,液氮冷却熔凝层和空气冷却熔凝层的腐蚀电位较原始镁合金分别降低了22 mV和29 mV,阳极腐蚀电流密度分别提高了1倍和2倍,说明激光熔凝使镁合金的耐腐蚀性能有所降低.

  17. 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.

  18. 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.

  19. Effect of Annealing on Microstructure and Tensile Properties of 5052/AZ31/5052 Clad Sheets

    Science.gov (United States)

    Nie, Huihui; Liang, Wei; Chi, Chengzhong; Li, Xianrong; Fan, Haiwei; Yang, Fuqian

    2016-05-01

    Three-layered 5052Al/AZ31Mg/5052Al (5052/AZ31/5052) clad sheets were fabricated by four-pass rolling and annealed under different conditions. Under the optimal annealing condition, homogeneous and equiaxial grains with an average AZ31 grain size of 5.24 µm were obtained and the maximum values of ultimate tensile strength and elongation of the clad sheet reached 230 MPa and 18%, respectively. Electron backscatter diffraction analysis showed that the AZ31 layer had a typical rolling texture with its c-axis parallel to the normal direction. The fraction of low-angle grain boundaries in the 5052 layer was nearly four times more than that in the AZ31 layer because of different deformation extent and recrystallization driving forces. The textures of Al3Mg2 and Mg17Al12 were similar to that of 5052 because of the deformation coordination during the rolling and recrystallization process. The orientation relationship between Mg17Al12 and AZ31 seemed to be (110) Mg17Al12//(10-11) AZ31.

  20. 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.

  1. 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.

  2. 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

  3. Simulation of cylindrical cup drawing of AZ31 sheet metal with crystal plasticity finite element method

    Science.gov (United States)

    Tang, Weiqin; Li, Dayong; Zhang, Shaorui; Peng, Yinghong

    2013-12-01

    As a light-weight structural material, magnesium alloys show good potential in improving the fuel efficiency of vehicles and reducing CO2 emissions. However, it is well known that polycrystalline Mg alloys develop pronounced crystallographic texture and plastic anisotropy during rolling, which leads to earing phenomenon during deep drawing of the rolled sheets. It is vital to predict this phenomenon accurately for application of magnesium sheet metals. In the present study, a crystal plasticity model for AZ31 magnesium alloy that incorporates both slip and twinning is established. Then the crystal plasticity model is implemented in the commercial finite element software ABAQUS/Explicit through secondary development interface (VUMAT). Finally, the stamping process of a cylindrical cup is simulated using the developed crystal plasticity finite element model, and the predicting method is verified by comparing with experimental results from both earing profile and deformation texture.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; DONG Chuang; TU Gan-feng

    2005-01-01

    The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone(HAZ), but also beyond HAZ, reaching over 250 μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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 °C. However, the impedance of the composited layer deceased when the curing temperature was more than 130 °C due to the carbonization of the silane layer.

  16. The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents.

    Science.gov (United States)

    Zhang, Yaowu; Kent, Damon; Wang, Gui; StJohn, David; Dargusch, Matthew S

    2014-11-01

    Mg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a cross-sectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24. Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at a ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes.

  17. 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.

  18. 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.

  19. 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.

  20. Tensile properties of AZ31 sheet/bar and effects of texture

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qing; G. ITOH; Y. MOTOHASHI

    2006-01-01

    For understanding the deformation mechanism of AZ31 Mg alloy, two kinds of specimen, hot-rolled sheet and extruded bar were tested in tension at room temperature. Relatively small grain sizes ranging from 32 to 8.7 (m are obtained by annealing at several temperatures. And then they were further cold-rolled with rolling angles of 0-, 45- and 90-, which is the angle between the rolling and the longitude direction of as-received specimen, and annealed at a temperature in recrystallization field. The yield stress were found from the stress-strain curve. The grain size dependence of the yield stress is found not in agreement with the Hall-Petch relationship. The texture of (0002) pole figure of each kind of specimen was tested by X-ray diffractometer. The specimen with strong basal texture shows large yield stress and low work-hardening rate, while the specimen with weak basal texture shows low yield stress and rapid work-hardening rate. These results are interpreted by the slip system activated in the different textures. A combined slip system was used to interpret the yield stress variation with the texture and the deformation mechanism was discussed.

  1. 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.

  2. 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

  3. Friction and Adhesion in Dry Warm Forging of Magnesium Alloy with Coated Tools

    Science.gov (United States)

    Matsumoto, Ryo; Kawashima, Hiroaki; Osakada, Kozo

    In order to develop forging process of magnesium alloys without lubrication, frictional behavior of magnesium alloy AZ31B (Mg-3%Al-1%Zn) is evaluated by a tapered plug penetration test under dry condition. The cemented tungsten carbide (WC) plugs polished to be a mirror-like surface are coated with diamond-like carbon (DLC) and TiAlN by physical vapor deposition (PVD). The cylindrical hollow billets of AZ31B are penetrated by the tapered plugs at a temperature of 200°C. The surface roughness of the hole of the billet, the adhesion length of AZ31B on the plug surface and the penetration load are measured. Compared with WC and TiAlN coating, it is found that DLC coating is effective in preventing AZ31B from adhering to the tool surface and reducing the penetration load.

  4. 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.

  5. 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

  6. 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

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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).

  12. 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.

  13. 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.

  14. Microstructure, mechanical properties, biocorrosion behavior, and cytotoxicity of as-extruded Mg-Nd-Zn-Zr alloy with different extrusion ratios.

    Science.gov (United States)

    Zhang, Xiaobo; Yuan, Guangyin; Niu, Jialin; Fu, Penghuai; Ding, Wenjiang

    2012-05-01

    Recently, commercial magnesium (Mg) alloys containing Al (such as AZ31 and AZ91) or Y (such as WE43) have been studied extensively for biomedical applications. However, these Mg alloys were developed as structural materials, not as biomaterials. In this study, a patented Mg-Nd-Zn-Zr (denoted as JDBM) alloy was investigated as a biomedical material. The microstructure, mechanical properties, biocorrosion behavior, and cytotoxicity of the alloy extruded at 320 °C with extrusion ratios of 8 and 25 were studied. The results show that the lower extrusion ratio results in finer grains and higher strength, but lower elongation, while the higher extrusion ratio results in coarser grains and lower strength, but higher elongation. The biocorrosion behavior of the alloy was investigated by hydrogen evolution and mass loss tests in simulated body fluid (SBF). The results show that the alloy extruded with lower extrusion ratio exhibits better corrosion resistance. The corrosion mode of the alloy is uniform corrosion, which is favorable for biomedical applications. Aging treatment on the as-extruded alloy improves the strength and decreases the elongation at room temperature, and has a small positive influence on the corrosion resistance in SBF. The cytotoxicity test indicates that the as-extruded JDBM alloy meets the requirement of cell toxicity.

  15. 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...

  16. 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 ...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Cold Metal Transfer joining of magnesium AZ31B-to-aluminum A6061-T6

    Energy Technology Data Exchange (ETDEWEB)

    Cao, R., E-mail: caorui@lut.cn [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Wen, B.F. [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Chen, J.H., E-mail: zchen@lut.cn [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Wang, Pei-Chung [Manufacturing Systems Research Lab General Motors (United States)

    2013-01-10

    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 {gamma}-Al{sub 12}Mg{sub 17} and Al-rich intermetallic {beta}-Al{sub 3}Mg{sub 2} were still produced in the weld. Fracture surfaces of CMT welded AZ31B-Al6061-T6 joints exhibited the Mg-rich intermetallic ({gamma}-Al{sub 12}Mg{sub 17}) which contributes to the weld strength degradation. To improve the joint, minimizing the content of the intermetallics especially

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. Effect of subsequent tension and annealing on microstructure evolution and strength enhancement of friction stir welded Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Renlong, E-mail: rlxin@cqu.edu.cn; Sun, Liyun; Liu, Dejia; Zhou, Zheng; Liu, Qing

    2014-04-01

    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

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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...

  12. 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

  13. 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.

  14. 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.

  15. Corrosion behavior of Mg and Mg-Zn alloys in simulated body fluid

    Institute of Scientific and Technical Information of China (English)

    GAO Jia-cheng; WU Sha; QIAO Li-ying; WANG Yong

    2008-01-01

    The corrosion behavior of Mg and Mg-Zn in simulated body fluid was studied.The mass loss of pure Mg,Mg-Zn-Zr and Mg-Zn-Zr-Y in simulated body fluid was measured using photovoltaic scale meter.Corrosion rate was determined through electrochemical tests.Finally,the corrosion mechanism was tbermodynamically studied.The results show that the corrosion rate decreases with the lapse of time for both pure Mg and Mg alloys.The purer the alloy,the borer the corrosion resistance exhibits.The corrosion behavior of Mg alloy is improved by the addition of trace Y.

  16. 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.

  17. 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

  18. 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.

  19. 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 ...

  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. 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.

  2. Electron Theory Research in Mg-Y Alloy

    Institute of Scientific and Technical Information of China (English)

    郭旭涛; 何良菊; 李培杰; 曾大本

    2004-01-01

    Adding yttrium to magnesium can improve the mechanical properties,especially the mechanical behavior at high temperature.The valence electron structures of Mg-Y alloy were analyzed with the empirical electron theory of solids and molecules(EET).Calculation shows that yttrium is on the fifth hybrid level and magnesium is on the third one in pure metal crystals.By comparing with aluminum in Mg-Al alloy,it is shown that the reason why the solution strengthening effect of yttrium is better than that of aluminum in Mg-Al alloy is the enhanced bond energy according to EET.And it is concluded from EET analysis that intermetallics Mg24Y5 can significantly improve the properties of magnesium alloys because yttrium atoms occupy the centers of the octahedron and Mg-Y bonds efficiently strengthen the alloy matrix.

  3. 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.

  4. 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

  5. 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

  6. 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].

  7. 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.

  8. 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)

  9. Effect of scandium on superplasticity of Al-Mg alloys

    Institute of Scientific and Technical Information of China (English)

    孝云祯; 高彩茹; 马宏声; 田士平

    2001-01-01

    The superplastic behavior of adding 0.22%Sc into the Al-6Mg alloy was studied by simple superplastic pretreatment process—warm rolling and cold rolling. The optimum superplastic temperature and strain rate of the alloys were defined and satisfactory results were obtained during the superplastic deformation at 811  K and initial strain rate 0=1.67×10-3 s-1. The average elongation of Al-6Mg-0.22Sc alloys reaches to 1  125%, and the maximum elongation is 1  200%, maximum m value (strain rate sensitive index) is 0.879. But under the same condition the elongation and maximum m value for Al-6Mg alloy were only 377% and 0.595, respectively. The superplastic deforming mechanism for Al-6Mg-0.22Sc alloys was also discussed.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Electron beam induced oxidation of Al–Mg alloy surfaces

    NARCIS (Netherlands)

    Palasantzas, G.; Agterveld, D.T.L. van; Hosson, J.Th.M. De

    2002-01-01

    Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates additiona

  4. 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.

  5. Thermodynamic modeling of the La-Mg-Y system and Mg-based alloys database

    Institute of Scientific and Technical Information of China (English)

    DU Zhenmin; GUO Cuiping; LI Changrong; ZHANG Weijing

    2006-01-01

    As an example of the La-Mg-Y system, the method how to set up the thermodynamic model of individual phases was introduced in the process of thermodynamic optimization. The solution phases (liquid, body-centered cubic,face-centered cubic, hexagonal close-packed and double hexagonal close-packed) were modeled with the Redlich-Kister equation. The compound energy model has been used to describe the thermodynamic functions of the intermetallic compounds in the La-Mg-Y systems. The compounds Mg2Y, Mg24Y5, Mg12La, Mg17La2, Mg41La5, Mg3La and Mg2La in the La-Mg-Y system were treated as the formulae (Mg, Y)2(La,Mg, Y), Mg24(La,Mg, Y)4Y, Mg12(La, Y), Mg17(La, Y)2,Mg41(La,Y)5, Mg3(La,Mg,Y) and Mg2(La,Y), respectively. A model (La,Mg,Y)0.5(La,Mg,Y)0.5 was applied to describe the compound MgM formed by MgLa and MgY in order to cope with the order-disorder transition between body-centered cubic solution (A2) and MgM with CsCl-type structure (B2) in the La-Mg-Y system. The Gibbs energies of individual phases were optimized in the La-Mg, La-Y and La-Mg-Y systems by CALPHAD technique. The projection of the liquidus surfaces for the La-Mg-Y system was predicted. The Mg-based alloys database including 36 binary and 15 ternary systems formed by Mg, Al, Cu, Ni, Mn, Zn and rare earth elements was set up in SGTE standard.

  6. 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.

  7. 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

  8. Microstructure and crystal growth direction of Al-Mg alloy

    Directory of Open Access Journals (Sweden)

    Ti-jun Chen

    2015-03-01

    Full Text Available The microstructures and crystal growth directions of permanent mould casting and directionally solidified Al-Mg alloys with different Mg contents have been investigated. The results indicate that the effect of Mg content on microstructure is basically same for the alloys prepared by these two methods. The primary grains change from cellular crystals to developed columnar dendrites, and then to equiaxed dendrites as the Mg content is increased. Simultaneously, both the cellular or columnar grain region and the primary trunk spacing decrease. All of these changes are mainly attributed to the constitutional supercooling resulting from Mg element. Comparatively, the cellular or columnar crystals of the directionally solidified alloys are straighter and more parallel than those of the permanent mould casting alloys. These have straight or wavy grain boundaries, one of the most important microstructure characteristics of feathery grains. However, the transverse microstructure and growth direction reveal that they do not belong to feathery grains. The Mg seemingly can affect the crystal growth direction, but does not result in the formation of feathery grains under the conditions employed in the study.

  9. 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.

  10. 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.

  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. Effect of Ni on Mg based hydrogen storage alloy Mg3Nd

    Institute of Scientific and Technical Information of China (English)

    TONG Yanqing; OUYANG Liuzhang; ZHU Min

    2006-01-01

    Magnesium-neodymium based alloys were prepared by induction melting in an alumina crucible under protection of pure argon atmosphere. XRD patterns show that the as-melted Mg-Nd and Mg3NdNi 0.1 diffraction peaks can be excellently indexed with D03 structure (BiF3 type, space group Fm3m ). The lattice constant of Mg3Nd phase is 0.7390 nm, which is determined by XRD analysis using Cohen's extrapolation method. The reversible hydrogen storage capacity reaches 1.95wt.% for Mg3Nd and 2.68wt.% for Mg3NdNi0.1 . The desorption of hydrogen takes place at 291 ℃ for Mg3Nd and at 250 ℃ for Mg3NdNi 0.1 . The alloys could absorb hydrogen at room temperature with rapid hydriding and dehydriding kinetics after only one cycle. The enthalpy (ΔH ) and entropy (ΔS ) of Mg3Nd-H dehydriding reaction were -68.2 kJ·mol-1 H2 and -0.121 kJ·(K·mol)-1 H2 determined by using van't Hoff plot according to the pressure-composition-isotherms (P-C-I) curve measured at different temperatures. Hydrogen absorption kinetic property of Mg3NdNi 0.1 alloy was also measured at room temperature.

  13. 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

  14. 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...

  15. In vitro and in vivo comparison of binary Mg alloys and pure Mg.

    Science.gov (United States)

    Myrissa, Anastasia; Agha, Nezha Ahmad; Lu, Yiyi; Martinelli, Elisabeth; Eichler, Johannes; Szakács, Gábor; Kleinhans, Claudia; Willumeit-Römer, Regine; Schäfer, Ute; Weinberg, Annelie-Martina

    2016-04-01

    Biodegradable materials are under investigation due to their promising properties for biomedical applications as implant material. In the present study, two binary magnesium (Mg) alloys (Mg2Ag and Mg10Gd) and pure Mg (99.99%) were used in order to compare the degradation performance of the materials in in vitro to in vivo conditions. In vitro analysis of cell distribution and viability was performed on discs of pure Mg, Mg2Ag and Mg10Gd. The results verified viable pre-osteoblast cells on all three alloys and no obvious toxic effect within the first two weeks. The degradation rates in in vitro and in vivo conditions (Sprague-Dawley® rats) showed that the degradation rates differ especially in the 1st week of the experiments. While in vitro Mg2Ag displayed the fastest degradation rate, in vivo, Mg10Gd revealed the highest degradation rate. After four weeks of in vitro immersion tests, the degradation rate of Mg2Ag was significantly reduced and approached the values of pure Mg and Mg10Gd. Interestingly, after 4 weeks the estimated in vitro degradation rates approximate in vivo values. Our systematic experiment indicates that a correlation between in vitro and in vivo observations still has some limitations that have to be considered in order to perform representative in vitro experiments that display the in vivo situation.

  16. 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.

  17. Modeling of the Thermal Field in Dissimilar Alloy Ultrasonic Welding

    Science.gov (United States)

    Jedrasiak, P.; Shercliff, H. R.; Chen, Y. C.; Wang, L.; Prangnell, P.; Robson, J.

    2015-02-01

    This paper describes a finite element model for predicting the temperature field in high power ultrasonic welding aluminum AA6111 to two dissimilar alloys, magnesium AZ31, and low carbon steel DC04. Experimental thermocouple and other evidence are used to infer the magnitude and distribution of the heat input to the workpiece, as a function of time, for each of the material combinations welded. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Mg welds. The microstructural model successfully predicts the thickness of the intermetallic layer, but the sensitivity of the results to temperature is demonstrated.

  18. 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.

  19. 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.

  20. Theorical study on mechanical properties of AZ31B Magnesium alloy Sheets under multiaxial loading

    Directory of Open Access Journals (Sweden)

    A. Znaidi

    2016-10-01

    Full Text Available Numerical simulation by plastic deformation of the shaping processes currently has a large industrial interest. It allows you to shorten the time of design and construction related products and tools to analyze and to optimize processes. An essential part of simulation tools is the constitutive law used to describe the material used. The activity of characterization and modeling of material behavior of the plastic deformation shaping remains a very important research field of activity; the objective of proposing laws of behavior used in computer codes, essentially based on finite element is sufficiently to represent the real behavior of materials. Considering the nature of the materials used and the stresses they experience the behavior laws account for several requirements which make them increasingly complicated. Among these requirements, we cite in particular plastic anisotropy, the great transformations, the complexity and diversity of loads, etc. The complexity of these laws makes them more difficult to implement and in particular to identify: the classic tests are no longer sufficient for identification. The objective of this work is based on two essential points: Suggest a construction strategy, particularly of identifying laws elastoplastic behavior anisotropic operational for the numerical simulation of plastic deformation shaping processes with particular attention to sheet metal magnesium. Magnesium sheet metal manufacturing process involves rolling operation. In a cost-cutting goal, this operation now takes place cold, implying a very marked anisotropy of the material at the output of the mill

  1. 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.

  2. Analysis of laser welded joint of microstructure and mechanical properties of dissimilar magnesium AZ31B and AZ91D%AZ31B/AZ91D 异种镁合金激光焊接头组织性能分析

    Institute of Scientific and Technical Information of China (English)

    刘军; 黄飞; 稼海星; 侯继军; 杜赵新

    2015-01-01

    Studies on the microstructure and properties of dissimilar magnesium AZ31B and AZ91D joints welded by CO2 laser using optical microscope,tensile test,microhardness test and etc are presented.The results show that a sound weld can be ob-tained with a laser power of 1 800 W,a welding speed of 600 mm/min and a flow rate of shielding gas of 15 L/min.Analysis of microstructure of welded joint shows that the heat affected zone is not apparent,the growth of the grains in base metal close to the fusion line are not obvious,and the grain size in weld is refined.X-ray diffraction shows that there areα-Mg andβ-Al12 Mg17 phases in the welded zone.EDS analysis shows that the element’s content of Mg,Al in the welded zone are between that of the base metal AZ91D and AZ31B.Tension results show that the fracture is mainly happened on AZ91D,which indicates that the tensile strength of joint is higher than the base metal AZ91D,and the dominant fracture mechanism is brittle fracture.The hard-ness of welded zone is higher than two base metals.%针对 AZ31B 和 AZ91D 异种镁合金材料的激光焊接问题,通过光学显微镜、拉伸试验、显微硬度测试等手段分析研究AZ31B 和 AZ91D 异种镁合金 CO2激光焊接头组织性能。结果表明:在功率为1800 W,焊接速度为600 mm/min,保护气流量为15 L/min 时,可以获得成形良好的焊缝。对焊接接头微观组织进行分析发现,接头热影响区不明显,熔合线附近母材侧晶粒未发生明显长大,焊缝晶粒明显细化;通过 XRD 检测可知焊缝区主要由α-Mg 和β-Al12 Mg17这2相组成;通过 EDS 能谱分析得到焊缝区 Mg、Al 元素的质量分数介于2种母材之间;通过拉伸试验发现,断裂位置位于 AZ91D 母材上,焊接接头抗拉强度高于AZ91D 母材,扫描断口显示断裂方式为脆性断裂;焊缝硬度高于2种母材硬度。

  3. 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.

  4. 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...

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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).

  11. 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...

  12. 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.

  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. 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.)

  15. 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. ...

  16. 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.

  17. 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

  18. Heat treatment of AlSi9Mg alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2008-04-01

    Full Text Available Processes of crystallization of alloys have decisive impact on structure of castings, and the same their utility characteristics. Knowledge about those processes constitutes a source of information to development of preparation of liquid metal and control of alloy preparation process within industry. Method of Thermal-Voltage-Derivative Analysis (ATND, developed by Faculty of Chipless Forming Technology enables registration of temperature and voltage curves, on which one can observe thermal and voltage effects being result of crystallization of phases and eutectic mixtures present on these curves in form of characteristic “peaks”. Temperature value read offs for these characteristic points become a basis to taking regression analysis aimed at obtaining of mathematical dependences illustrating effect of changes of these values on change of impact resistance of dispersion hardened AK9 alloy. The paper presents an attempt of implementation of Thermal-Voltage-Derivative Analysis method to determination of temperature of hyperquenching and ageing processes of AK9 (AlSi9Mg silumin. Investigated alloy had undergone typical treatments of refining and modification, and next the heat treatment. Temperature range for the heat treatment has been determined on base of ATND melting curves.

  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. Microstructural evolution of Mg-7Al-2Sn Mg alloy during multi-directional impact forging

    Directory of Open Access Journals (Sweden)

    M.G. Jiang

    2015-09-01

    Full Text Available Multi-directional impact forging (MDIF was applied to a Mg-7Al-2Sn (wt.% Mg alloy to investigate its effect on the microstructural evolution. MDIF process exhibited high grain refinement efficiency. After MDIF 200 passes, the grain size drastically decreased to 20 µm from the initial coarse grains of ~500 µm due to dynamic recrystallization (DRX. Meanwhile, original grain boundaries remained during MDIF and large numbers of fine spherical β-Mg17Al12 particles dynamically precipitated along the original grain boundaries with high Al concentration, acting as effective pinning obstacles for the suppression of DRXed grain growth. Besides, micro-cracks nucleated during MDIF and propagated along the interface between the remained globular or cubic Al-Mn particles and Mg matrix.

  1. Microstructures and mechanical properties of Al-Mg and Al-Zn-Mg based alloys containing minor scandium and zirconium

    Institute of Scientific and Technical Information of China (English)

    尹志民; 姜锋; 潘青林; 郭飞跃; 朱大鹏; 宋练鹏; 曾渝; 王涛

    2003-01-01

    A series of Al-Mg and Al-Zn-Mg based alloys with and without Sc, Zr were prepared by ingot metallurgy. The mechanical properties and microstructures of the studied alloys under different treatment conditions were studied. In addition, the existing form and acting mechanism of minor Sc and Zr in Al-Mg and Al-Zn-Mg based alloys were analyzed and discussed. The following conclusions can be drawn. First, adding of minor Sc and Zr to those alloys can increase the strength of Al-Mg and Al-Zn-Mg based alloys by 25%, while the ductility can remain in 15% and 8%, respectively. Second, in Al-Mg and Al-Zn-Mg based alloys, minor Sc and Zr mainly exist in two forms of aluminides containing Sc and Zr, one is Al3(Sc,Zr)I precipitated from the melt during solidification, the other is Al3(Sc,Zr)Ⅱ precipitated during homogenization. The former is the most effective grain refiner for α(Al) solid solution matrix, and the latter is coherent with the matrix and can strongly pin dislocations and subboundaries, which can effectively restrain recrystallization of the alloys during hot deformation, annealing and solid solution. Third, strengthening caused by adding minor Sc and Zr to the studied alloys is mainly due to fine-grain strengthening, precipitation strengthening and substructure strengthening of Al3(Sc, Zr) caused by restraining recrystallization.

  2. 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.

  3. Thermal stability of Al-Mg-Sc-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei-tao; YAN De-sheng; RONG Li-jian

    2006-01-01

    The thermal stability of Al3(Sc,Zr) precipitates in the cold worked Al-Mg-Sc-Zr alloy after elevated temperature exposure was investigated. The evaluation was conducted using room temperature tensile, Vicker's hardness, optical metallography and scanning electron microscope (SEM) with the backscatter. The results show that the Al3(Sc,Zr) precipitates and mechanical properties have no obvious change, and the grains keep elongated along the working direction as that in cold worked sample after exposure at 300 ℃ for 1 000 h. The coarsening of Al3(Sc,Zr) precipitates occurs and is no longer effective on the recrystallization resistance, and partial recrystallization is observed after 400 ℃ exposure. In particular, after 500 ℃ exposure, the hardness decreases drastically and the alloy has fully recrystallized due to the obvious coarsening of Al3(Sc,Zr) precipitates.

  4. In Vitro Degradation Behavior of Ternary Mg-Zn-Se and Mg-Zn-Cu Alloys as Biomaterials

    Science.gov (United States)

    Persaud-Sharma, Dharam; Budiansky, Noah

    2013-01-01

    In this study, the corrosion behavior of Mg-Zn-Se and Mg-Zn-Cu alloys was investigated to evaluate their corrosion behavior related to use as implantable biomaterials. The corrosion behavior of these alloys and a commercially available Mg-Zn alloy were examined using static solution electrochemical testing, dynamic solution gravimetric testing, ion leaching testing, and microscopic evaluation. Fluctuations in the pH of the Dulbecco’s Modified Eagles Medium (DMEM) used for the gravimetric and ion leaching immersion testing were also recorded over the 30-day duration to assess whether the media conditions induced by the alloy degradation would permit for cellular survival. Weight loss experimentation and electrochemical tests revealed the Mg-Zn-Cu alloy to have the greatest corrosion rate. PMID:24465245

  5. In vitro biocompatibility of Ti-Mg alloys fabricated by direct current magnetron sputtering.

    Science.gov (United States)

    Hieda, Junko; 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 7d 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-17 Mg alloy and Ti-33 Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti-55 Mg 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-17 Mg alloy, Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 μg/cm(2), respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films after the immersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti-33 Mg film. However, many cracks are observed in the Ti-55 Mg 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. Consequently, it is revealed that the Ti-33 Mg

  6. 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

  7. 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.

  8. 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.

  9. 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.

  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. 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

  12. 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.

  13. Effects of chemical coating with Ni on electrochemical properties of Mg2Ni hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of nickel coating on the electrochemical properties of Mg2Ni hydrogen storage alloys are presented in this paper. X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques were employed to examine the crystal structure and surface morphologies of the bare and Ni-coated Mg2Ni alloys. The electrochemical properties of alloys were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that Ni coating not only decreased the charge transfer resistance, but also decreased the H atom diflusion resistance for Mg2Ni alloys. It was also found that Ni coating effectively improved the discharge capacity, but decreased the cycling performance of the as-synthesized Ni-coated Mg2Ni alloys. The discharge current has a great impact on the cycling performance of the as-synthesized Ni-coated Mg2Ni alloys.

  14. 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.

  15. 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.

  16. 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.

  17. Corrosion behavior of an Al-6Mg-Sc-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    XU Guangxing; TAO Binwu; LIU Jianhua; LI Songmei

    2005-01-01

    The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy.The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium resulted in (Al3Sc, Zr) particles that greatly refmed grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.

  18. 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.

  19. 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...

  20. 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.

  1. 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 ...

  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. 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%.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. Effect of mischmetal and yttrium on microstructures and mechanical properties of Mg-Al alloy

    Institute of Scientific and Technical Information of China (English)

    张诗昌; 魏伯康; 蔡启舟; 王立世

    2003-01-01

    The effect of yttrium and mischmetal(MMs) on the as-cast and solid solution treated structures of Mg-Al alloys with different Al-contents was investigated. The results show that the MMs in Mg-Al alloy existed in rodAl4 (Ce, La)compound while Y in Mg-Al alloy in polygonal Al2 Y compound. The amount of Mg17 Al12 in Mg-Al al-loy is decreased with increasing Y or MMs addition, and Mg17 Al12 intermetallic compound is changed from continu-ous network to discontinuous one. The Al4 (Ce, La) and Al2 Y compounds are not dissolved into Mg-Al alloy matrixduring solid solution treatment so that their high heat stability can be exhibited. The experiment of mechanical prop-erties indicate that elongation and impact toughness of the Mg-Al-Y alloy with polygonal Al2 Y compound are higherthan those of Mg-Al-MMs alloy with rod Al4 (Ce, La) compound.

  15. Facile fabrication of hydrophobic surfaces on mechanically alloyed-Mg/HA/TiO2/MgO bionanocomposites

    International Nuclear Information System (INIS)

    Highlights: • Mg/HA/TiO2-based nanocomposite was produced using mechanical alloying. • The hydrophobic surface coverage was fabricated on the mechanical alloyed samples by annealing. • The morphological characteristics, phase evolution and wettability of nanocomposites and the hydrophobic surface coverage were investigated. • The activation energies and reaction kinetic of the powder mixture of nanocomposites were calculated. - Abstract: The effect of mechanical alloying and post-annealing on the phase evolution, microstructure, wettability and thermal stability of Mg–HA–TiO2–MgO composites was investigated in this study. Phase evolution and microstructure analysis were performed using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and atomic force microscopy, as well as the wettability determined by contact angle measurements with SBF. The 16-h mechanical alloying resulted in the formation of MgTiO3, CaTiO3, Mg3(PO4)2 and Mg(OH)2 phases and a decrease in wettability of the nanocomposites. A hydrophobic film with hierarchical structures comprising nanoflakes of MgTiO3, nano-cuboids of CaTiO3, microspheres of Mg3(PO4)2 and Mg(OH)2 was successfully constructed on the surface of the Mg-based nanocomposites substrates as a result of the post-annealing process. After 1-h annealing at 630 °C, the synthesized hydrophobic surface on the nanocomposite substrates decreased the wettability, as the 8-h-mechanically alloyed samples exhibited a contact angle close to 93°. The formation activation energies and reaction kinetics of the powder mixture were investigated using differential thermal analysis and thermal gravimetric analysis. The released heat, weight loss percentage and reaction kinetics increased, while the formation activation energies of the exothermic reactions decreased following an increase in the milling time

  16. Corrosion Behavior of AlSi10Mg Alloy Produced by Additive Manufacturing (AM vs. Its Counterpart Gravity Cast Alloy

    Directory of Open Access Journals (Sweden)

    Avi Leon

    2016-06-01

    Full Text Available The attractiveness of additive manufacturing (AM relates to the ability of this technology to rapidly produce very complex components at affordable costs. However, the properties and corrosion behavior, in particular, of products produced by AM technology should at least match the properties obtained by conventional technologies. The present study aims at evaluating the corrosion behavior and corrosion fatigue endurance of AlSi10Mg alloy produced by selective laser melting (SLM in comparison with its conventional counterpart, gravity cast alloy. The results obtained indicate that the corrosion resistance of the printed and cast alloys was relatively similar, with a minor advantage to the printed alloy. The corrosion fatigue endurance of the printed alloy was relatively improved compared to the cast alloy. This was mainly attributed to the significant differences between the microstructure and defect characteristics of those two alloys.

  17. 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

    2016-08-01

    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 mechanical properties of Mg-based alloys. In this study, the REE holmium (Ho) was added to an Mg-1Zr-2Sr alloy at different concentrations of Mg1Zr2SrxHo alloys (x = 0, 1, 3, 5 wt. %) and the microstructure, mechanical properties, degradation behaviour and biocompatibility of the alloys were systematically investigated. The results indicate that the addition of Ho to Mg1Zr2Sr led to the formation of the intermetallic phases MgHo3, Mg2Ho and Mg17Sr2 which resulted in enhanced mechanical strength and decreased degradation rates of the Mg-Zr-Sr-Ho alloys. Furthermore, Ho addition (≤5 wt. %) to Mg-Zr-Sr alloys led to enhancement of cell adhesion and proliferation of osteoblast cells on the Mg-Zr-Sr-Ho alloys. The in vitro biodegradation and the biocompatibility of the Mg-Zr-Sr-Ho alloys were both influenced by the Ho concentration in the Mg alloys; Mg1Zr2Sr3Ho exhibited lower degradation rates than Mg1Zr2Sr and displayed the best biocompatibility compared with the other alloys.

  18. 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 mechanical properties of Mg-based alloys. In this study, the REE holmium (Ho) was added to an Mg-1Zr-2Sr alloy at different concentrations of Mg1Zr2SrxHo alloys (x = 0, 1, 3, 5 wt. %) and the microstructure, mechanical properties, degradation behaviour and biocompatibility of the alloys were systematically investigated. The results indicate that the addition of Ho to Mg1Zr2Sr led to the formation of the intermetallic phases MgHo3, Mg2Ho and Mg17Sr2 which resulted in enhanced mechanical strength and decreased degradation rates of the Mg-Zr-Sr-Ho alloys. Furthermore, Ho addition (≤5 wt. %) to Mg-Zr-Sr alloys led to enhancement of cell adhesion and proliferation of osteoblast cells on the Mg-Zr-Sr-Ho alloys. The in vitro biodegradation and the biocompatibility of the Mg-Zr-Sr-Ho alloys were both influenced by the Ho concentration in the Mg alloys; Mg1Zr2Sr3Ho exhibited lower degradation rates than Mg1Zr2Sr and displayed the best biocompatibility compared with the other alloys. PMID:27553403

  19. The influence of MgH2 on the assessment of electrochemical data to predict the degradation rate of Mg and Mg alloys.

    Science.gov (United States)

    Mueller, Wolf-Dieter; Hornberger, Helga

    2014-06-26

    Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE) is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

  20. The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

    Directory of Open Access Journals (Sweden)

    Wolf-Dieter Mueller

    2014-06-01

    Full Text Available Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

  1. Structure and corrosion resistance of aluminium AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys

    Directory of Open Access Journals (Sweden)

    J. Szewczenko

    2010-07-01

    Full Text Available Purpose: The aim of the work was the evaluation of corrosion resistance and structure of aluminium AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys.Design/methodology/approach: The corrosion resistance tests of investigated alloys were carried out by means of potentiodynamic method registering anodic polarization curves in 3.5% NaCl solution at room temperature. Registering anodic polarization curves was conducted at the potential rate equal to 1mV/s. As the reference electrode was used saturated calomel electrode (SCE and the auxiliary electrode was platinum electrode. Mechanical properties were evaluated on the basis of Vickers hardness test. The test was realized with the use of Hauser hardness tester. The observations of the surface morphology after corrosive tests were carried out using Digital Scanning Electron Microscope DSM 940 OPTON.Findings: The investigations of corrosion resistance of examined aluminium alloys shows that the highest corrosion resistance in 3.5% NaCl solution was observed for AlZn5Mg1 aluminium alloy.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of analysed alloys because better corrosion resistance, lightweight of aluminium and its alloys makes them as most attractive for the steel replacement in shipbuilding.Originality/value: The corrosion behaviour in chloride solution of AlMg2.5; AlMg5Mn and AlZn5Mg1 alloys was investigated.

  2. Homogenization and Recrystallization of Al-6Mg Alloys with and without Sc and Zr

    Institute of Scientific and Technical Information of China (English)

    姜锋; 尹志民; 黄伯云; 贺跃辉; 陈苏里

    2004-01-01

    Plates of Al-6Mg alloys with and without scandium were prepared by semi-continuous cast, homogenization, hot-rolled, cold-rolled and annealing. Based on studying of effects of temperature and time on hardness and conductivity during homogenization, it was found that homogenization of ingot with Sc and Zr can result in dispersion strengthening. Recrystallization temperature of alloys was studied by hardness method and optical metallographic method. Staring recrystallization temperature of Al-6Mg alloys with Sc and Zr is 375 ℃, increasing by 150 ℃ than Al-6Mg alloys without Sc and Zr. Mechanical properties (σb, σ0.2, δ) of hot-rolled alloy with Sc and Zr are 400 MPa, 280 MPa and 18%; cold-rolled and anneal alloy with Sc and Zr are 420 MPa, 310 MPa and 12% respectively.

  3. Cytocompatibility of magnesium alloys after surface fluoridation tested by human bone marrow mesenchymal cells%人骨髓间充质干细胞检测表面氟化处理镁合金材料的细胞相容性

    Institute of Scientific and Technical Information of China (English)

    姜海英; 闫征斌; 张照; 艾红军

    2011-01-01

    BACKGROUND: AZ31B magnesium alloy with surface flouridization is a new type of magnesium alloy developed by Institute of Metal Research, Chinese Academy of Sciences. Its biocompatibility is unclear.OBJECTIVE: To observe the cytocompatibility of magnesium alloys with surface fluoridation tested by human bone marrow mesenchymal cells (BMSCs).METHODS: Human BMSCs were identified and cultured. The AZ31B magnesium alloy was taken as control and the AZ31B magnesium alloy with surface fluoridation was experimental group. Human BMSCs were the test cells. Leaching liquor of the alloy in both groups was used for cell compatibility experiments in vitro in order to evaluate the biocompatibility of AZ31B magnesium alloy.RESULTS AND CONCLUSION: The cell survival rate of AZ31B magnesium alloys with surface fluoridation was significantly higher than AZ31B magnesium alloys without surface fluoridation. The toxicity of cells in the leaching liquor of AZ31B magnesium alloys with surface fluoridation was Grade 1 and was non-toxic to the basic cell growth. The biocompatibility of the AZ31B magnesium alloys with surface fluoridation is superior to the AZ31B magnesium alloys without surface fluoridation.%背景:表面氟化处理的AZ31B镁合金是中科院金属研究所新研制的镁合金,是否具有良好的生物相容性尚不确切.目的:以人骨髓间充质干细胞作为检测细胞,评价表面氟处理的镁合金材料的细胞相容性.方法:人骨髓间充质干细胞培养并予以鉴定,将镁合金AZ31B作为对照组,氟处理的镁合金AZ31B材料为实验组.以人骨髓间充质干细胞作为检测细胞,取两组材料浸提液进行体外细胞相容性实验,评价氟处理的镁合金AZ31B材料的生物相容性.结果与结论:与未经氟处理镁合金AZ31B材料相比,经氟处理镁合金AZ31B材料能显著提高细胞存活率,细胞毒性分级1级,对细胞生长基本无毒性作用.结果表明,经氟处理镁合金AZ31B材料生物相容性

  4. Preparing different phases of Mg-Li-Sm alloys by molten salt electrolysis in LiCl-KCl-MgCl_2-SmCl_3 melts

    Institute of Scientific and Technical Information of China (English)

    韩伟; 田阳; 张密林; 叶克; 赵全友; 魏树权

    2010-01-01

    Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl2-SmCl3 melts at 670 °C.The electrolysis process and phase control of Mg-Li-Sm alloys were studied.The microstructures of α,α+β,β phases of Mg-Li-Sm alloys were characterized by X-ray diffraction(XRD) and optical microscope(OM).Analysis of scanning electron microscopy(SEM) and EDS mapping analysis showed that Mg distributed homogeneously in Mg-Li-Sm alloys.EDS result showed that the distribution of Sm was more at...

  5. Study on the solidification microstructure in AZ91D Mg alloy after laser surface melting

    International Nuclear Information System (INIS)

    Laser surface melting (LSM) is known to enhance the wear and corrosion resistance of Mg alloys, but its effect on microstructural evolution of Mg alloys is not well understood. An effort has been made to study the effect of rapid solidification following LSM on the microstructural evolution of AZ91D Mg alloy. The results of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy indicated that the solidification microstructure in the laser-melted zone was mainly cellular/dendrite structure of primarily α-Mg phase and continuous network of β-Mg17Al12 phase. Numerical prediction of the laser-melted zone suggested that cooling rates increased strongly from the bottom to the top surface in the irradiated regions. An attempt has been made to correlate dendrite cell sizes of the solidification microstructure with the cooling rates in the laser-treated AZ91D Mg alloy.

  6. Microstructure, tensile properties and compressive creep resistance of Mg-(5-8.5)%Sn-2%La alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The microstructure,tensile properties and compressive creep resistance of permanent-mould cast Mg-(5-8.5)%Sn-2%La (mass fraction)alloys wgre investigated.The results show that Mg-(5-8.5)%Sn-2%La alloys are all composed of α-Mg phase,Mg2Sn and Mg-La-Sn compounds.Compared with those of Mg-5%Sn binary alloy,the grain size and the content of Mg2Sn compound in Mg-5%Sn-2%La alloy are decreased.With the increase of Sn content in Mg-(5-8.5)%Sn-2%La alloys,the content of Mg2Sn compound increases,while that of Mg-Sn-La compound changes little.In addition,the investigation suggests that the thermally stable Mg-Sn-La and Mg2Sn compounds Can improve the tensile properties and compressive creep resistance ofthe alloys.

  7. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    Science.gov (United States)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  8. Liquation Cracking in Arc and Friction-Stir Welding of Mg-Zn Alloys

    Science.gov (United States)

    Wagner, Dustin C.; Chai, Xiao; Tang, Xin; Kou, Sindo

    2015-01-01

    As compared to Al alloys, which are known to be susceptible to liquation ( i.e., liquid formation) and liquation-induced cracking, most Mg alloys have a lower eutectic temperature and thus are likely to be even more susceptible. The present study was conducted to study liquation and liquation cracking in Mg alloys during arc welding and friction-stir welding (FSW). Binary Mg-Zn alloys were selected as a model material in view of their very low eutectic temperature of 613 K (340 °C). Mg-Zn alloys with 2, 4, and 6 wt pct of Zn were cast and welded in the as-cast condition by both gas-tungsten arc welding (GTAW) and FSW. A simple test for liquation cracking was developed, which avoided interference by solidification cracking in the nearby fusion zone. Liquation and liquation cracking in GTAW were found to be in the decreasing order of Mg-6Zn, Mg-4Zn, and Mg-2Zn. Liquation cracking occurred in FSW of Mg-6Zn but not Mg-4Zn or Mg-2Zn. Instead of a continuous ribbon-like flash connected to the weld edge, small chips, and powder covered the weld surface of Mg-6Zn. The results from GTAW and FSW were discussed in light of the binary Mg-Zn phase diagram and the curves of temperature vs fraction solid during solidification.

  9. Effect of Scandium on Corrosion Resistance of Welded Joint of Al-6Mg-Zr Alloy

    Institute of Scientific and Technical Information of China (English)

    Tao Binwu; Li Songmei; Liu Jianhua

    2005-01-01

    The corrosion resistance of welded joints of Al-6Mg-Sc-Zr alloy was studied by neutral salt spray and exfoliation corrosion methods. The microstructure of welded joints was investigated by using optical microscope and transmission electron micrograph (TEM). It is demonstrated that the welded joints of Al-6Mg-Sc-Zr alloy are more corrosion resistance, comparing with Al-6Mg-Zr alloy. The addition of scandium in the alloy results in (Al3Sc, Zr) particles, potently refined grains and restrained recrystallization process. The formation of homogeneous, discontinuous distribution of β-phase in welded joints improves the corrosion resistance of welded joints of Al-Mg-Zr alloy with high level content of magnesium.

  10. Effect of Ca addition on the corrosion behavior of Mg-Al-Mn alloy

    Science.gov (United States)

    Yang, Jiang; Peng, Jian; Nyberg, Eric A.; Pan, Fu-sheng

    2016-04-01

    The microstructures and corrosion resistance of magnesium-5 wt% aluminum-0.3 wt% manganese alloys (Mg-Al-Mn) with different Ca additions (0.2-4 wt%) were investigated. Results showed that with increasing Ca addition, the grain of the alloys became more refined, whereas the corrosion resistant ability of the alloys initially increased and then decreased. The alloy with 2 wt% Ca addition exhibited the best corrosion resistance, attributed to the effect of the oxide film and (Mg,Al)2Ca phases which were discontinuously distributed on the grain boundaries. These phases acted as micro-victims, they preferentially corroded to protect the α-Mg matrix. The oxide film formed on the alloy surface can hinder the solution further to protect the α-Mg matrix.

  11. Electrochemical hydrogen storage properties of La0.95Mg2.05Ni9 alloy prepared by mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    蒙冕武; 刘心宇; 成钧; 周怀营

    2004-01-01

    The structure, microstructure, thermal stability and hydriding characteristics of amorphous La0.95-Mg2.05 Ni9 have been investigated with differential thermal analysis, X-ray diffraction, scanning electron microscopy and battery test. It is found that the increase in mechanical alloying time leads to enhancement in thermal stabilities of amorphous La0. 95 Mg2.05 Ni9 alloy. The amorphous alloy has good charge/discharge ability at room temperature (430 mA · h · g-1 ), but the discharge capacity decreases seriously during cycling tests due to the crystallization of amorphous and oxidization of magnesium on the particle surface in alkaline aqueous solution.

  12. Age-hardening characteristic of an Al-Zn-Mg-Cu alloy produced by spray deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Feng; XIONG Baiqing; ZHANG Yongan; ZHU Baohong; LIU Hongwei; ZHANG Zhihui; WANG Zixing

    2007-01-01

    Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by spray atomization and deposition technique. GP zones and age-hardening process in the alloy were investigated using high-resolution electron microscopy (HREM), selected area diffraction (SAD), and differential scanning calorimetry (DSC) analysis. The results indicated that spray deposition process accelerated the aging kinetics of the alloy at an aging temperature of 120℃, thereby reducing the peak aging time to 16 h.GPI and GPⅡ are the two types of zones that are major precipitates for the alloy under peak-aged condition. The precipitation sequence for the alloy is also discussed.

  13. Thermostability of Al-Cu-Mg-Fe-Ni Alloy with Trace Scandium and Zirconium

    Institute of Scientific and Technical Information of China (English)

    Yu Kun; Li Songrui; Li Wenxian

    2000-01-01

    Three Al-Cu-Mg-Fe-Ni-Sc-Zr ingot metallurgy alloys with different compositions had been prepared. The hardness variations of cold-rolled alloy plates during annealing process had been measured. The tensile properties at both ambient and elevated temperatures were also measured. The microstructures of alloys were observed by using optical microscope and TEM. It was found that the dispersed Al3(Sc, Zr) particles could pin dislocations, stabilize substructures and impede the movement of boundaries. The ambient and elevated temperature properties of alloy with Al3(Sc, Zr) particles were improved. And the tensile strength of alloy did not improve obviously with rich iron and nicker addition.

  14. Density functional theory (DFT) study on the hydrolysis behavior of degradable Mg/Mg alloys for biomedical applications

    Science.gov (United States)

    Nezafati, Marjan

    Magnesium-based (Mg and/or Mg alloys) materials possess many advantageous physicochemical/biological characteristics such as good biocompatibility and similarity of the mechanical properties to the human bone tissue, which renders this material a promising candidate for the biomedical and implant applications. One of the most attractive features of Mg-based materials is the degradability in the physiological environment. With the burst of research on the biodegradable materials for the healthcare device applications, Mg and its alloys attracted a strong attention in the bioengineering field in recent years. However, the major limitation of applying Mg-based materials to biomedical applications is the fast degradation/corrosion rate with regards to the healing process time-span. In the present thesis, an atomistic model employing the density-functional theory (DFT) has been developed to study the hydrolysis process by understanding the influences of commonly used alloying elements (zinc (Zn), calcium (Ca), aluminum (Al), and yttrium (Y)) and the crystallographic orientation of the dissolution surfaces (basal (0001), prism (1010), and pyramidal (1011) planes) on the corrosion behavior. These parameters are known to strongly impact the initial hydrolysis phenomena of Mg-based materials. To develop the atomistic computational model, we have implemented the Dmol3 software package in conjunction with PBE (Perdew, Burke and Ernzerhof) correlation energy functional in the GGA (generalized gradient approximation) scheme. Throughout the thesis, we performed three sets of calculations, i) surface energy, ii) dissolution potential, and iii) water adsorption computations, to examine the hydrolysis mechanism and the subsequent corrosion/degradation of Mg/Mg alloys. The total energy changes of various Mg-based systems in different conditions for these surface energies, dissolution behavior, and tendency of the system for adsorbing the water molecule were quantified. The results

  15. Microstructures and properties of rapidly solidified Mg-Zn-Ca alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Ternary alloys based on the Mg-Zn-Ca system were produced by twin-roll rapid solidification. The alloys were characterized by OM, SEM, HRTEM, XRD, EDS and Micro-hardness. The results show that the rapidly solidified flakes are of frnedendritic cell structures with the cell size ranging from 1 to 5 μn. The Mg-6Zn-5Ca alloy in RS and annealing (200 ℃ for 1 h) states are mainly composed of α-Mg, Mg2Ca, Ca2Mg6, Zn3 and a small quantity of Mg51Zn20, MgZn2 and Mg2Zn3. Micro-hardness increases with the increment of Ca content and age hardening occurs after aging at 200 ℃ in the flakes probably due to the precipitation strengthening of the fine precipitates Mg2Ca and Ca2Mg6, Zn3. Some phases at the grain boundary in Mg-6Zn-5Ca alloy are identified by means of HRTEM, which may be beneficial to the improvement in thermal stability of the alloy.

  16. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg alloys

    Directory of Open Access Journals (Sweden)

    M. Kaczorowski

    2007-04-01

    Full Text Available 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 heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM and transmission (TEM electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.

  17. Effect of Deep Cryogenic Treatment on Microstructure and Properties of AE42 Mg Alloy

    Science.gov (United States)

    Bhale, Pranav; Shastri, H.; Mondal, A. K.; Masanta, M.; Kumar, S.

    2016-09-01

    The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties including corrosion behavior of the squeeze-cast AE42 alloy has been investigated. For comparison, the same has also been studied on the untreated alloy. Both the untreated and deep cryogenic-treated (DCTed) alloys comprised α-Mg and Al4RE phases. Volume fraction of the Al4RE phase in the AE42 alloy reduced gradually following DCT carried out from 4 to 16 h. Ductility and UTS increase significantly with a marginal increase in YS of all the DCTed alloys. The improvement was attributed to the dissolution of the brittle Al4RE phase following DCT. Among the alloys employed, the best tensile properties were obtained for the 16-h DCT alloy due to its lowest content of the brittle Al4RE phase. Creep resistance of the DCTed alloys was lower than that of the untreated alloy owing to the presence of less amount of thermally stable intermetallic Al4RE phase. Wear resistance of the alloy reduces following DCT due to reduced hardness of the DCTed alloys. The untreated alloy exhibits the best corrosion resistance, whereas poor corrosion resistance of the DCTed alloys is attributed to the reduced amount of Al4RE phase that fails to built a corrosion resistance barrier.

  18. Effect of Deep Cryogenic Treatment on Microstructure and Properties of AE42 Mg Alloy

    Science.gov (United States)

    Bhale, Pranav; Shastri, H.; Mondal, A. K.; Masanta, M.; Kumar, S.

    2016-07-01

    The effect of deep cryogenic treatment (DCT) on microstructure and mechanical properties including corrosion behavior of the squeeze-cast AE42 alloy has been investigated. For comparison, the same has also been studied on the untreated alloy. Both the untreated and deep cryogenic-treated (DCTed) alloys comprised α-Mg and Al4RE phases. Volume fraction of the Al4RE phase in the AE42 alloy reduced gradually following DCT carried out from 4 to 16 h. Ductility and UTS increase significantly with a marginal increase in YS of all the DCTed alloys. The improvement was attributed to the dissolution of the brittle Al4RE phase following DCT. Among the alloys employed, the best tensile properties were obtained for the 16-h DCT alloy due to its lowest content of the brittle Al4RE phase. Creep resistance of the DCTed alloys was lower than that of the untreated alloy owing to the presence of less amount of thermally stable intermetallic Al4RE phase. Wear resistance of the alloy reduces following DCT due to reduced hardness of the DCTed alloys. The untreated alloy exhibits the best corrosion resistance, whereas poor corrosion resistance of the DCTed alloys is attributed to the reduced amount of Al4RE phase that fails to built a corrosion resistance barrier.

  19. Effect of minor Sc and Zr on superplasticity of Al-Mg-Mn alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment.The superplastic properties and the mechanism of superplastic deformation of the two alloys were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The elongation to failure of Al-Mg-Mn-Sc-Zr alloy is larger than that of Al-Mg-Mn alloy at the same temperature and initial strain rate. The variation of strain rate sensitivity index is similar to that of elongation to failure. In addition, Al-Mg-Mn-Sc-Zr alloy exhibits higher strain rate superplastic property. The activation energies of the two alloys that are calculated by constitutive equation and linear regression method approach the energy of grain boundary diffusion. The addition of Sc and Zr decreases activation energy and improves the superplastic property of Al-Mg-Mn alloy. The addition of Sc and Zr refines the grain structure greatly. The main mechanism of superplastic deformation of the two alloys is grain boundary sliding accommodated by grain boundary diffusion. The fine grain structure and high density of grain boundary,benefit grain boundary sliding, and dynamic recrystallization brings new fine grain and high angle grain boundary which benefit grain boundary sliding too. Grain boundary diffusion, dislocation motion and dynamic recrystallization harmonize the grain boundary sliding during deformation.

  20. Mechanical Responses of Superlight β-Based Mg-Li-Al-Zn Wrought Alloys under Resonance

    Science.gov (United States)

    Song, Jenn-Ming; Lin, Yi-Hua; Su, Chien-Wei; Wang, Jian-Yih

    2009-05-01

    To extend the application of lightweight Mg alloys in the automotive industry, this study suggests a β-based Mg-Li alloy (LAZ1110) with superior vibration fracture resistance by means of material design. In the cold-rolled state, a strengthened β matrix by the additions of Al and Zn, as well as intergranular platelike α precipitates, which are able to stunt the crack growth, contributes to a comparable vibration life with commercial Mg-Al-Zn alloys under a similar strain condition.

  1. Mechanical and corrosion properties of binary Mg-Dy alloys for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang Lei, E-mail: lei.yang@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Huang Yuanding; Peng Qiuming; Feyerabend, Frank; Kainer, Karl Ulrich; Willumeit, Regine; Hort, Norbert [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany)

    2011-12-15

    Microstructure, mechanical and corrosion properties of binary magnesium-dysprosium (Mg-5, 10, 15, 20 wt.% Dy) alloys were investigated for medical applications. In the as-cast condition, the distribution of Dy is quite inhomogeneous. Mg-10Dy alloy exhibits a moderate tensile and compression yield strength, and the best elongation and corrosion resistance. After T4 (solutionizing) treatment, the distribution of Dy becomes homogeneous. The tensile and compression yield strength of all Mg-Dy alloys decreases. The elongation remains unchanged, while the corrosion resistance is largely improved after T4 treatment.

  2. Influence of solution treatment on microstructure, mechanical and corrosion properties of Mg-4Zn alloy

    OpenAIRE

    Hongmin Jia; Xiaohui Feng; Yuansheng Yang

    2015-01-01

    The solution treatment parameters, mechanical properties and corrosion behavior of binary Mg-4Zn alloy were investigated. The results showed that after the solution treatment at 335 °C for 16 h, Mg-4Zn alloy had an ultimate tensile strength of 184.13 MPa and elongation of 9.43%. Furthermore, the corrosion resistance was evaluated by electrochemical measurements and immersion tests in 3.5% NaCl solution. The results revealed that the corrosion current density of the solution treatment Mg alloy...

  3. Surface modification of an Mg-1Ca alloy to slow down its biocorrosion by chitosan.

    Science.gov (United States)

    Gu, X N; Zheng, Y F; Lan, Q X; Cheng, Y; Zhang, Z X; Xi, T F; Zhang, D Y

    2009-08-01

    The surface morphologies before and after immersion corrosion test of various chitosan-coated Mg-1Ca alloy samples were studied to investigate the effect of chitosan dip coating on the slowdown of biocorrosion. It showed that the corrosion resistance of the Mg-Ca alloy increased after coating with chitosan, and depended on both the chitosan molecular weight and layer numbers of coating. The Mg-Ca alloy coated by chitosan with a molecular weight of 2.7 x 10(5) for six layers has smooth and intact surface morphology, and exhibits the highest corrosion resistance in a simulated body fluid.

  4. Surface modification of an Mg-1Ca alloy to slow down its biocorrosion by chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X N; Zheng, Y F; Lan, Q X [State Key Laboratory for Turbulence and Complex System and College of Engineering, Peking University, Beijing 100871 (China); Cheng, Y; Xi, T F [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhang, Z X [Biomedical Engineering Research Center, Research Institute of Peking University in Shenzhen, Shenzhen 518057 (China); Zhang, D Y, E-mail: gxn139888@pku.edu.c, E-mail: yfzheng@pku.edu.c, E-mail: 8lanqiuxiang@163.co, E-mail: chengyan@pku.edu.c, E-mail: top5460@163.co, E-mail: xitingfei@tom.co, E-mail: zhangdeyuan@lifetechmed.co [Lifetech Scientific (Shenzhen) Co. Ltd, Hi-Tech Park, Shenzhen 518000 (China)

    2009-08-15

    The surface morphologies before and after immersion corrosion test of various chitosan-coated Mg-1Ca alloy samples were studied to investigate the effect of chitosan dip coating on the slowdown of biocorrosion. It showed that the corrosion resistance of the Mg-Ca alloy increased after coating with chitosan, and depended on both the chitosan molecular weight and layer numbers of coating. The Mg-Ca alloy coated by chitosan with a molecular weight of 2.7 x 10{sup 5} for six layers has smooth and intact surface morphology, and exhibits the highest corrosion resistance in a simulated body fluid.

  5. Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

    Institute of Scientific and Technical Information of China (English)

    H.S.Liu; B.Zhang; G.P.Zhang

    2011-01-01

    Al/Mg alloy multilayered composites were produced successfully at the lower temperature (280℃) by accumulative roll bonding (ARB) processing technique. The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy. Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites. It is found that Vickers hardness, bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass. Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load. Strengthening and fracture mechanisms of the composite are analyzed.

  6. Microstructure features and mechanical properties of a UFG Al-Mg-Si alloy produced via SPD

    Science.gov (United States)

    Bobruk, E.; Sabirov, I.; Kazykhanov, V.; Valiev, R.; Murashkin, M.

    2014-08-01

    The effect of equal channel angular pressing in parallel channels (ECAP-PC) and subsequient artificial ageing on the microstructure and room temperature mechanical properties of the commercial aluminum alloys 6063 (Al-0.6Mg-0.5Si, wt.%) and 6010 (Al-0.8Mg-1.0Si-0.15Cu-0.25Mn, wt.%) was investigated. It was shown that mechanical strength of the ECAP-PC processed Al alloys is higher compared to that achieved in these alloys after conventional thermo-mechanical processing. Prior ECAP- PC solution treatment and post-ECAP-PC artificial aging can additionally increase the mechanical strength of both Al alloys. Under optimal artificial ageing conditions, the yield strength (YS) of 299 MPa and ultimate tensile strength (UTS) of 308 MPa was achieved in the 6063 alloy, whereas YS of 423 MPa and UTS of 436 MPa was achieved in the 6010 alloy.

  7. Comparison of microstructure and corrosion properties of Al-Zn-Mg-Cu alloys 7150 and 7010

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-chang; FAN Xi-gang; REN Shi-yu; ZHANG Xin-mei; ZHANG Bao-you

    2006-01-01

    The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa higher than that of 7010 alloy.The 7010 alloy exhibits higher resistance to stress corrosion cracking as compared with the 7150 alloy. The coarse Cu-bearing particles are detrimental to the resistance to stress corrosion cracking. The increase of size of matrix and subgrain boundary precipitates decreases the susceptibility of stress corrosion. The anodic dissolution and hydrogen embrittlement govern the cracking process. The severity of stress corrosion cracking is shown to be related to the coarse Cu-bearing particles, matrix and subgrain precipitates in Al-Zn-Mg-Cu alloys.

  8. Corrosion Behavior of Welded Joints of Al-6Mg Alloy with Trace Scandium Addition

    Institute of Scientific and Technical Information of China (English)

    Wang Yue

    2004-01-01

    Al-6Mg alloy with trace Sc addition was prepared by means of melting-casting.The samples of the welded joints of Al-6Mg alloy with trace Sc addition were made by method of manual argon-arc welding.Neutral salt spray test was carried out by referring to GB/T10125-1997 and GB6384-1986 practice.Exfoliation testing was carried out in accordance with the method of Al-Mg alloy exfoliation corrosion test.The corrosion behaviors of the welded joints of AlMg alloy with high level of Mg and trace Sc addition were studied.The microstructures of the welded joints were observed by using optical microscope and transmission electron microscope.The corrosion resistance mechanism of the alloy was also involved.This work intended to determine if the welded joints of Al-6Mgalloy with trace Sc addition can have excellent corrosion resistance, when their strength are clearly improved.The results show that trace content of Sc refines the grains of alloys effectively, raises remarkably the corrosion resistance of the welded joints of Al-6Mg alloy with trace Sc addition.The corrosion resistance mechanisms are that there is free of continuous grain boundary precipitation or network which could be susceptible to corrosion in the microstructure of welded joints.

  9. Influence of boron addition on the grain refinement and mechanical properties of AZ91 Mg alloy

    International Nuclear Information System (INIS)

    This article reports the effect of boron addition on the grain refinement efficiency and mechanical properties of AZ91 magnesium alloy. The results show that the addition of boron in the form of Al-4B master alloy, significantly refines the grain size of AZ91 alloy. This refinement is due to the presence of AlB2 particles, which act as potential nucleants for Mg grains. Improved mechanical properties are obtained with the addition of boron due to the finer grains.

  10. Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

    International Nuclear Information System (INIS)

    The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation in size of matrix strengthening η′ (MgZn2) and also the size and distribution of grain boundary η (MgZn2) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers

  11. Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

    Energy Technology Data Exchange (ETDEWEB)

    Rout, Prasanta Kumar, E-mail: prasantonnet55@yahoo.com; Ghosh, M.M.; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

    2015-06-15

    The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation in size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.

  12. Cytotoxicity assessment of adipose-derived mesenchymal stem cells on synthesized biodegradable Mg-Zn-Ca alloys.

    Science.gov (United States)

    Fazel Anvari-Yazdi, Abbas; Tahermanesh, Kobra; Hadavi, Seyed Mohammad Mehdi; Talaei-Khozani, Tahereh; Razmkhah, Mahboobeh; Abed, Seyedeh Mehr; Mohtasebi, Maryam Sadat

    2016-12-01

    Magnesium (Mg)-based alloys have been extensively considered as biodegradable implant materials for orthopedic surgery. Mg and its alloys are metallic biomaterials that can degrade in the body and promote new bone formation. In this study, the corrosion behavior and cytotoxicity of Mg-Zn-Ca alloys are evaluated with adipose-derived mesenchymal stem cells (ASCs). Mg-2Zn and Mg-2Zn-xCa (x=1, 2 and 3wt.%) alloys were designated. Mg alloys were analyzed with scanning electron microscopy and potentiodynamic polarization. To understand the in-vitro biocompatibility and cytotoxicity of Mg-2Zn and Mg-2Zn-xCa alloys, ASCs were cultured for 24 and 72h in contact with 10%, 50% and 100% extraction of all alloys prepared in DMEM. Cell cytotoxicity and viability of ASCs were examined by MTT assay. Alloying elements including Zn and Ca improved the corrosion resistance of alloys were compared with pure Mg. The cytotoxicity results showed that all alloys had no significant adverse effects on cell viability in 24h. After 72h, cell viability and proliferation increased in the cells exposed to pure Mg and Mg-2Zn-1Ca extracts. The release of Mg, Zn and Ca ions in culture media had no toxic impacts on ASCs viability and proliferation. Mg-2Zn-1Ca alloy can be suggested as a good candidate to be used in biomedical applications.

  13. Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects.

    Science.gov (United States)

    Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K

    2016-06-07

    A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications.

  14. Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects

    Science.gov (United States)

    Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K.

    2016-01-01

    A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications. PMID:27271057

  15. Ageing Effect on Hardness and Microstructureof Al-Zn-Mg Alloys

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Experimental results of the investigation on the hardness of two AI-Zn-Mg alloys [Al-10.0 Zn 4.0 Mg and AI-8.5 Zn-3.0 Mg (wt pct)] aged in the temperature range 60~310C for different intervals of time from 1/4 h to 168 h are presented. Both the alloys were found to show identical behaviour of hardness with ageing time. Alloy with higher Zn and Mg content had higher hardness than the alloy with lower solute content. There were three ranges of temperature in which different types of precipitates formed and affected the hardness. Some of the grain boundaries were found to migrate and precipitate free zone has been observed.

  16. Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

    Directory of Open Access Journals (Sweden)

    Chen Jun

    2009-05-01

    Full Text Available The effects of rare earth (RE elements Y and Nd on the microstructure and mechanical properties of Mg-6Al magnesium alloy were investigated. The results show that a proper level of RE elements can obviously refi ne the microstructure of Mg-6Al magnesium alloys, reduce the quantity of β-Mg17Al12 phase and form Al2Y and Al2Nd phases. The combined addition of Y and Nd dramatically enhances the tensile strength of the alloys in the temperature range of 20-175℃. When the content of RE elements is up to 1.8%, the values of tensile strength at room temperature and at 150℃ simultaneously reach their maximum of 253 MPa and 196 MPa, respectively. The main mechanisms of enhancement in the mechanical properties of Mg-6Al alloy with Y and Nd are the grain refi ning strengthening and the dispersion strengthening.

  17. Influence of solution treatment on microstructure, mechanical and corrosion properties of Mg-4Zn alloy

    Directory of Open Access Journals (Sweden)

    Hongmin Jia

    2015-09-01

    Full Text Available The solution treatment parameters, mechanical properties and corrosion behavior of binary Mg-4Zn alloy were investigated. The results showed that after the solution treatment at 335 °C for 16 h, Mg-4Zn alloy had an ultimate tensile strength of 184.13 MPa and elongation of 9.43%. Furthermore, the corrosion resistance was evaluated by electrochemical measurements and immersion tests in 3.5% NaCl solution. The results revealed that the corrosion current density of the solution treatment Mg alloy was 11.2 µA/cm−2, it was lower than 15.8 µA/cm−2 for the as-cast Mg alloy under the same conditions, which was greatly associated with the micro-cathode effect of the second phases.

  18. Grain Coarsening Behavior of Mg-Al Alloys with Mischmetal Addition

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Small addition of mischmetal (MM) into aluminum alloys can lead to grain refinement. However, it is still uncertain whether the same effect applies to Mg-Al alloys. This work indicated that small amount of mischmetal addition ranging from 0.1% to 1.2% (mass fraction) did not cause grain refinement in Mg-Al alloys. On the contrary, they tended to coarsen the grains. When added into Mg-Al alloys, MM reacted preferentially with Al to form Al11MM3 phase. As Al11MM3 phase mainly distributed within α-Mg grains than at grain boundaries, it had little effect in restricting grain growth. In addition, MM reacted with Al8(Mn, Fe)5 or ε-AlMn particles to form Al-MM-Mn compounds, thus it reduced the amount of heterogeneous nuclei in the melt and resulted in remarkable grain coarsening.

  19. Corrosion Behavior and Surface Modification of Mg-Zn Implant Alloys

    Science.gov (United States)

    Ghayad, I. M.; Maamoun, M. A.; Metwally, W. A.; El-Baradie, Z. M.; Abdel-Azim, A. N.

    2016-10-01

    In this study, Mg-Zn alloys (1-4 wt.% Zn) were fabricated with high-purity raw materials using a clean melting process (fluxless method) and a protective atmosphere of CO2 + 0.4 SF6. The as-cast microstructures of the investigated alloys were characterized by optical and scanning electron microscopes, EDS and XRD. Corrosion properties of the prepared alloys were examined in simulated body fluid by electrochemical techniques and immersion test (hydrogen evolution method). Surface modification of the prepared alloys was performed using micro-arc oxidation (MAO) treatment and hydroxyapatite (HA) coating. Microstructure observation revealed that Zn was completely dissolved in the α-Mg matrix up to 2 wt.%. Higher Zn content led to a reduction in the grain size and the development of a second phase (MgZn2). Corrosion testing results revealed that Mg-1,2,3 wt.% Zn have almost the same degradation rate, whereas Mg-4Zn has the highest degradation rate. HA coating on MAO-treated magnesium alloys formed a dense and compact layer on the alloy surface, which had largely improved surface properties and enhanced corrosion resistance of the prepared alloys.

  20. Dissolution of Cu/Mg Bearing Intermetallics in Al-Si Foundry Alloys

    Science.gov (United States)

    Javidani, Mousa; Larouche, Daniel; Grant Chen, X.

    2016-10-01

    Evolutions of the Cu/Mg bearing intermetallics were thoroughly investigated in four Al-Si hypoeutectic alloys containing various Cu (1 and 1.6 wt pct) and Mg (0.4 and 0.8 wt pct) contents. The area fractions of Cu/Mg bearing phases before and after solution heat treatment (SHT) were quantified to evaluate the solubility/stability of the phases. Two Mg-bearing intermetallics (Q-Al5Cu2Mg8Si6, π-Al8FeMg3Si6) which appear as gray color under optical microscope were discriminated by the developed etchant. Moreover, the concentrations of the elements (Cu, Mg, and Si) in α-Al were analyzed. The results illustrated that in the alloys containing ~0.4 pct Mg, Q-Al5Cu2Mg8Si6 phase was dissolved after 6 hours of SHT at 778 K (505 °C); but containing in the alloys ~0.8 pct Mg, it was insoluble/ partially soluble. Furthermore, after SHT at 778 K (505 °C), Mg2Si was partially substituted by Q-phase. Applying a two-step SHT [6 hours@778 K (505 °C) + 8 hours@798 K (525 °C)] in the alloys containing ~0.4 pct Mg helped to further dissolve the remaining Mg bearing intermetallics and further modified the microstructure, but in the alloys containing ~0.8 pct Mg, it caused partial melting of Q-phase. Thermodynamic calculations were carried out to assess the phase formation in equilibrium and in non-equilibrium conditions. There was an excellent agreement between the experimental results and the predicted results.

  1. Analysis of microstructure and strengthening in CuMg alloys deformed by equal channel angular pressing

    OpenAIRE

    Rodriguez-Calvillo, P.; Cabrera Marrero, José M.

    2015-01-01

    The microstructural and strengthening behavior of two CuMg alloys, with 0.2 and 0.5 m.-% of Mg, were analyzed after severe plastic deformation by Equal Channel Angular Pressing (ECAP). Both alloys were passed through a 90° inner angle ECAP die at room temperature up to 16 passes following route Bc. The EBSD analysis of the deformed microstructure revealed a significant grain refinement after the 2nd pass. Average grain sizes as fine as 0.31 and 0.24 µm for the CuMg0.2 and CuMg0.5, respectivel...

  2. Microstructure and corrosion behavior of electrodeposited nano-crystalline nickel coating on AZ91 Mg alloy

    International Nuclear Information System (INIS)

    Highlights: • Activation, zincating, and Cu electrodeposition were used as pretreatment processes for electrodeposition of nickel coatings. • Nano-crystalline nickel coatings were successfully electrodeposited onto the AZ91 Mg alloys. • Effect of nickel electrodeposited coating on the corrosion resistance of AZ91 Mg alloy has been studied. - Abstract: In order to enhance the corrosion resistance, nickel coating was electrodeposited onto AZ91 Mg alloy. Activation, zincating, and Cu electrodeposition used as pretreatment processes for better adhesion and corrosion performance of the nickel over layer. The corrosion properties of the AZ91 Mg alloy, nickel electroplated AZ91 Mg alloy, and pure nickel was assessed via polarization and electrochemical impedance spectroscopy (EIS) methods in 3.5 wt% NaCl solution. Moreover, the structure of the coating was investigated by means of X-ray diffraction, whereas specimen’s morphology and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Measurements revealed that the coating has a nano-crystalline structure with the grain size of 95 nm. Corrosion results showed superior corrosion resistance for the coated AZ91 Mg alloy as the corrosion current density decreased from 2.5 × 10−4 A cm−2, for the uncoated sample, to 1.5 × 10−5 A cm−2, for coated specimen and the corrosion potential increased from −1.55 V to −0.98 V (vs. Ag/AgCl) at the same condition

  3. Corrosion of Mg alloy AZ91D in the presence of living cells.

    Science.gov (United States)

    Seuss, F; Seuss, S; Turhan, M C; Fabry, B; Virtanen, S

    2011-11-01

    Mg and Mg alloys are of interest for biodegradable implants as they readily corrode in biological fluids, and dissolved Mg ions are nontoxic. Even though it is well known that Mg dissolution leads to pH increase in the surroundings, the effect of the corrosion-induced alkalization on the biological environment has not been studied in detail. We therefore explored the interactions between corrosion-induced pH increase and cell growth on Mg alloy AZ91D surface. Cell adhesion and spreading on the alloy surface is unimpeded initially. However, with time a large fraction of cells de-adhere. We attribute this to the observed increase of the pH in the cell culture medium in the process of alloy dissolution. Cytotoxicity tests with HeLa cells grown on glass surfaces confirm that cell death increases with increasing alkalinity of the cell culture medium. We also show that a the cells that adhere on the Mg alloy surface act as a corrosion-blocking surface layer. In consequence, a slower pH increase in the medium takes place when the alloy surface is covered with cells. Electrochemical impedance spectroscopy measurements (EIS) verify that a cell layer slows down the corrosion process.

  4. Effect of rare earth elements on the microstructure of Mg-Al alloys

    Directory of Open Access Journals (Sweden)

    T. Rzychoń

    2006-04-01

    Full Text Available Purpose: The automotive use of magnesium is currently restricted to low-temperature structural components. Rare earth additions such as Ce, Nd, La and Pr are known to improve the creep performance. The aim of the research was to determine the effect of rare earths elements on the as-cast microstructure of magnesium alloys containing 4 wt% aluminum.Design/methodology/approach: The study was conducted on Mg-4Al-2RE (AE42 and a new Mg-4Al-4RE (AE44 alloys in the as-cast condition. The microstructure was characterized by optical microscopy (Olympus GX-70 and a scanning electron microscopy (Hitachi S3400 equipped with an X-radiation detector EDS (VOYAGER of NORAN INSTRUMENTS. The phase identification of these alloys was identified by X-ray diffraction (JDX-75.Findings: The microstructure of AE42 alloy consists of α-Mg solid solution with divorced eutectic Mg17Al12 + α-Mg, RE-rich phases and Mn-rich phase. The increase of RE contents from 2 wt% to 4 wt% leads to a change of microstructure of these alloys. In AE44 alloy was observed globular, lamellar and acicular precipitations of Al11RE3 and Al3RE phases. Moreover, there was found globular Mn-rich phase existence, but the Mg17Al12 phase was not observed.Research limitations/implications: The increase of RE content to 4 wt% caused the formation of new phases in the microstructure and prevented the formation Mg17Al12 phase. These factors can improve the creep resistance of the Mg-Al-RE alloys. The future research will contain creep tests and microstructural investigations of cast and die-cast alloys using TEM microscopy.Practical implications: The improvement of creep resistance of Mg-Al alloys can cause their application in automotive industry on the elevated-temperature structural components (above 150 °C. Results of investigation may be useful for preparing die casting technology of the Mg-Al-RE alloys.Originality/value: paper includes the results of microstructural investigations of new AE44

  5. Optimization of parameters and study of joint microstructure of resistance spot welding of magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    Wang Yarong; Zhang Zhongdian; Li Dongqing

    2006-01-01

    Experimental investigations on the DC spot welding of Mg alloy AZ31B are presented. Experiments are carried out to study the influence of spot welding parameters (electrode force, welding heat input and welding time) on the tensile shear load and the diameter of nugget, based on an orthogonal test and analysis method. The optimum parameters are as follows:electrode force is 2 000 N, welding heat input is 80% and welding time is 6 cycles. The microstructure of spot weld is single fine equiaxed crystals in the nugget, of which the structure is β-Mg17Al12 precipitated on α-Mg boundaries induced by nonequilibrium freezing. And the surface condition of the workpiece has great influence on the joint quality.

  6. Effect of Zn addition on microstructure and mechanical properties of an Al-Mg-Si alloy

    Institute of Scientific and Technical Information of China (English)

    Lizhen Yan; Yongan Zhang; Xiwu Li; Zhihui Li; Feng Wang; Hongwei Liu; Baiqing Xiong

    2014-01-01

    In the present work, an Al-0.66Mg-0.85Si-0.2Cu alloy with Zn addition was investigated by electron back scattering diffraction (EBSD), high resolution electron microscopy (HREM), tensile and Erichsen tests. The mechanical properties of the alloy after pre-aging met the standards of sheet forming. After paint baking, the yield strength of the alloy was improved apparently. GP(II) zones andηʹphases were formed during aging process due to Zn addition. With the precipitation of GP zones,β″phases, GP(II) zones andηʹphases, the alloys displayed excellent mechanical properties.

  7. Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

    Institute of Scientific and Technical Information of China (English)

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin

    2010-01-01

    The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.

  8. Corrosion Behavior of Extruded near Eutectic Al-Si-Mg and 6063 Alloys

    Institute of Scientific and Technical Information of China (English)

    Yuna Wu; Hengcheng Liao

    2013-01-01

    In this work,a comparison study on corrosion behavior of extruded near eutectic Al-12.3%Si-0.26%Mg and 6063 alloys has been carried out by mass loss test in 4% H2SO4 aqueous solution in the open air and potentiodynamic polarization test in 3.5 wt.% NaCl aqueous solution.Results indicate that the corrosion resistance of the near eutectic Al-Si-Mg alloy is less than that of 6063 alloy.Macro/microscopy and scanning electron microscopy results clearly show the difference of the corrosion progress of these two alloys in 4% H2SO4 aqueous solution.The corrosion type of 6063 alloy is pitting corrosion.The Mg2Si and AlFeSi particles and surface defects act as nucleation sites for pitting,and the amount and distribution of them have a significant effect on the pitting behavior.For the near eutectic alloy,there are two types of corrosion cells.One is between the extruded primary α-Al and the eutectic,the other is between the eutectic Al and eutectic Si particles.Combination of these two types of corrosion cells leads to a lower corrosion resistance,a higher mass loss of the near eutectic alloy compared with 6063 alloy,and the formation of the paralleling corroded grooves.

  9. Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tarakci, Mehmet, E-mail: mtarakci@gyte.edu.tr

    2011-12-15

    The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

  10. Study on strength and fracture toughness of Al-Zn-Mg-Cu-Ti(-Sn alloys

    Directory of Open Access Journals (Sweden)

    Yan A.

    2015-01-01

    Full Text Available The strength and fracture toughness of Al-Zn-Mg-Cu-Ti(-Sn alloys were investigated by performing tensile and plane strain fracture toughness (KIC tests. Detailed observations with optical, scanning electron and transmission electron microscopy were conducted to analyze microstructure and fracture surfaces of the alloys. The results revealed that addition of Sn refined the solution-aging grain size of matrix and reduced coarsening rate of precipitate during aging. Narrower precipitation free zones and more discontinuous distribution of grain boundary precipitates were observed to be displayed in the Sn-containing alloy. Small size second phase particles Mg2Sn were observed to form in the Sn-containing alloy and distribute in the fine dimples of fracture surface. These features of microstructure were believed to impart higher strength and fracture toughness of the Sn-containing alloy on overaging.

  11. Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Min Zhu

    2013-10-01

    Full Text Available Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH2 are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys.

  12. As-cast microstructure of Mg-Al-Zn magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing; PAN Fu-sheng; YANG Ming-bo; LI Zhong-sheng

    2006-01-01

    The research achievements on as-cast microstructure in Mg-Al-Zn alloy were summarized. Under permanent mould cast condition, there are four kinds of primary compounds with distinct crystallographic morphology, Mg17Al12(γ),Mg32(Al,Zn)49 (τ), MgZn (ε) and a ternary icosahedral quasi-crystalline compound (Q). Accordingly, Mg-Al-Zn alloy can be grouped into γ-, τ-, ε- and Q-type alloy by each characteristic compound. The volume fraction of γ-Mg17Al12 in commercial γ-type alloy increases with increasing Al content. MgZn and MgxAlyZnz ternary complex compounds emerge with the change of the element content Al and Zn and Zn/Al concentration ratio. A practical phase diagram showing microstructure constituent change with composition was proposed. The addition of micro-alloying elements Y and Sr results in not only obvious refinement of eutectic cluster but also eutectic morphological change from block to granule.

  13. Microstructure analysis and corrosion behavior of biodegradable Mg-Ca implant alloys

    International Nuclear Information System (INIS)

    Highlights: → Evaluation of corrosion mechanism and solidification behavior of Mg-xCa. → Microstructure of Mg-xCa alloys were characterized by XRD, OM, SEM and EDS. → Thermal analy