Mechanical Properties of Laser Weldment of V-4Cr-4Ti Alloy

International Nuclear Information System (INIS)

Heo, Nam-Jin; Nagasaka, Takuya; Muroga, Takeo; Nishimura, Arata; Shinozaki, Kenji; Watanabe, Hideo

2003-01-01

The effect of the laser welding condition on properties of the weldment, such as bending, tensile and charpy impact properties were investigated in a V-4Cr-4Ti alloy (NIFS-HEAT- 2). The microstructural and microchemical development in the weldment was also investigated for mechanistic study of the impurity behavior during the welding. Increase in hardness occurred in the weld zone. The hardening was due to the dissolution of the large and small precipitates existed in the base metal before welding. The degree of hardening varied with a distance from the bead center. The absorption energy by the impact test increased with the decrease in the input power density during the laser welding. The impact absorption energy of the weld, which is similar to that of the base metal, was obtained by optimizing the welding condition

A quasi-in-situ EBSD observation of the transformation from rolling texture to recrystallization texture in V-4Cr-4Ti alloy

Energy Technology Data Exchange (ETDEWEB)

Peng, Lixia [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China); Li, Xiongwei [Institute of Metal Research, China Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Fan, Zhijian [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan Province 621900 (China); Jiang, Chunli; Zhou, Ping [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China); Lai, Xinchun, E-mail: laixinchun@caep.cn [Institute of Materials Research, China Academy of Engineering Physics, Jiangyou, Sichuan Province 621908 (China)

2017-04-15

Recrystallization texture evolution of rolled V-4Cr-4Ti alloy has been investigated by quasi-in-situ EBSD (electron back-scattering diffraction) method. Concurrently, the precipitates were characterized by SEM (Scanning Electron Microscopy). It was found that both the initial rolling textures and the distribution of the precipitates affected the formation of the recrystallization texture. It was revealed that the texture transformations of (558) 〈110〉 + (665) 〈110〉 to (334) 〈483〉 + (665) 〈1 1 2.4〉 were possibly attributed to the selective drag induced by the sparsely dispersed Ti-rich precipitates. While the densely distributed Ti-rich precipitates were responsible for the randomized recrystallization texture. Finally, when the precipitates were absent, the orientation changes from (112) 〈110〉 and (558) 〈110〉 to (111) 〈112〉 and (001) <110> to (001) <520> were observed. - Highlights: • Micro recrystallization texture evolution in V-4Cr-4Ti alloys is reported for the first time. • The volume fraction of Ti-rich precipitates has significant effect on the recrystallization texture evolution. • The dissolution of the Ti-rich precipitates above 1100 °C induces the strengthening of (111) <112> texture.

Performance of V-4Cr-4Ti material exposed to DIII-D tokamak environment

Energy Technology Data Exchange (ETDEWEB)

Tsai, H.; Chung, H.M.; Smith, D.L. [Argonne National Lab., IL (United States)] [and others

1997-04-01

Test specimens made with the 832665 heat of V-4Cr-4Ti alloy were exposed in the DIII-D tokamak environment to support the installation of components made of a V-4Cr-4Ti alloy in the radiative divertor of the DIII-D. Some of the tests were conducted with the Divertor Materials Evaluation System (DiMES) to study the short-term effects of postvent bakeout, when concentrations of gaseous impurities in the DIII-D chamber are the highest. Other specimens were mounted next to the chamber wall behind the divertor baffle plate, to study the effects of longer-term exposures. By design, none of the specimens directly interacted with the plasma. Preliminary results from testing the exposed specimens indicate only minor degradation of mechanical properties. Additional testing and microstructural characterization are in progress.

Synthesis and microstructure characterization of Ni-Cr-Co-Ti-V-Al high entropy alloy coating on Ti-6Al-4V substrate by laser surface alloying

International Nuclear Information System (INIS)

Cai, Zhaobing; Jin, Guo; Cui, Xiufang; Liu, Zhe; Zheng, Wei; Li, Yang; Wang, Liquan

2016-01-01

Ni-Cr-Co-Ti-V-Al high-entropy alloy coating on Ti-6Al-4V was synthesized by laser surface alloying. The coating is composed of a B2 matrix and (Co, Ni)Ti 2 compounds with few β-Ti phases. Focused ion beam technique was utilized to prepare TEM sample and TEM observations agree well with XRD and SEM results. The formation of HEA phases is due to high temperature and rapid cooling rate during laser surface alloying. The thermodynamic parameters, ΔH mix , ΔS mix and δ as well as Δχ, should be used to predict the formation of the BCC solid solution, but they are not the strict criteria. Especially when Δχ reaches a high value (≥ 10%), BCC HEA will be partially decomposed, leading to the formation of (Co, Ni)Ti 2 compound phases. - Highlights: •Preparing HEA coating on Ti-6Al-4V by laser surface alloying is successful. •The synthesized HEA coating mainly consists of BCC HEA and (Co, Ni)Ti 2 compounds. •FIB technology was used to prepare the sample for TEM analysis. • ΔH mix , ΔS mix and δ as well as Δχ, should be all used to predict the formation of solid solution.

Assessment of the radiation-induced loss of ductility in V-Cr-Ti alloys

Energy Technology Data Exchange (ETDEWEB)

Rowcliffe, A.F.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

1997-04-01

Alloys based on the V-Cr-Ti system are attractive candidates for structural applications in fusion systems because of their low activation properties, high thermal stress factor (high thermal conductivity, moderate strength, and low coefficient of thermal expansion), and their good compatibility with liquid lithium. The U.S. program has defined a V-4Cr-4Ti (wt %) alloy as a leading candidate alloy based upon evidence from laboratory-scale (30 kg) heats covering the approximate composition range 0-8 wt % Ti and 5 to 15 wt % Cr. A review of the effects of neutron displacement damage, helium, and hydrogen generation on mechanical behavior, and of compatibility with lithium, water, and helium environments was presented at the ICFRM-5 conference at Clearwater in 1991. The results of subsequent optimization studies, focusing on the effects of fast reactor irradiation on tensile and impact properties of a range of alloys, were presented at the ICFRM-6 conference at Stresa in 1993. The primary conclusion of this work was that the V-4Cr-4Ti alloy composition possessed a near-optimal combination of physical and mechanical properties for fusion structural applications. Subsequently, a production-scale (500 kg) heat of V-4Cr-4Ti (Heat No. 832665) was procured from Teledyne Wah-Chang, together with several 15 kg heats of alloys with small variations in Cr and Ti. Further testing has been carried out on these alloys, including neutron irradiation experiments to study swelling and mechanical property changes. This paper discusses ductility measurements from some of these tests which are in disagreement with earlier work.

Fabrication of a 1200 kg Ingot of V-4Cr-4Ti for the DIII-D Radiative Divertor Program

International Nuclear Information System (INIS)

Johnson, W.R.; Smith, J.P.

1998-01-01

Vanadium chromium titanium alloys are attractive materials for fusion reactors because of their high temperature capability and their potential for low neutron active and rapid activation decay. A V-4Cr-4Ti alloy has been selected in the U.S. as the current leading candidate vanadium alloy for future use in fusion reactor structural applications. General Atomics (GA), in conjunction with the Department of Energy's (DOE) DIII-D Program, is carrying out a plan for the utilization of this vanadium alloy in the DIII-D tokamak. The plan will culminate in the fabrication, installation, and operation of a V-4Ti alloy structure in the DIII-D Radiative Divertor (RD) upgrade. The deployment of vanadium alloy will provide a meaningful step in the development and technology acceptance of this advanced material for future fusion power devices. Under a GA contract and material specification, an industrial scale 1200 kg heat (ingot) of a V-4Cr-4Ti alloy has been produced and converted into product forms by Wah Chang of Albany, Oregon (WCA). To assure the proper control of minor and trace impurities which affect the mechanical and activation behavior of this vanadium alloy, selected lots of raw vanadium base metal were processed by aluminothermic reduction of high purity vanadium oxide, and were then electron beam melted into two high purity vanadium ingots. The ingots were then consolidated with high purity Cr and Ti, and double vacuum-arc melted to obtain a 1200 kg V-4Cr-4Ti alloy ingot. Several billets were extruded from the ingot, and were then fabricated into plate, sheet, and rod at WCA. Tubing was subsequently processed from plate material. The chemistry and fabrication procedures for the product forms were specified on the basis of experience and knowledge gained from DOE Fusion Materials Program studies on previous laboratory scale heats and a large scale ingot (500 kg)

Tensile properties of V-Cr-Ti alloys after exposure in hydrogen-containing environments

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.

1998-01-01

A systematic study has been initiated at Argonne National Laboratory to evaluate the performance of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake in the samples and its influence on the microstructure and tensile properties of the alloys. At present, the principal effort has focused on the V-4Cr-4Ti alloy of heat identified as BL-71; however other alloys (V-5Cr-5Ti alloy of heats BL-63, and T87, plus V-4Cr-4Ti alloy from General Atomics [GA]) are also being evaluated. Other variables of interest are the effect of initial grain size on the tensile behavior of the alloys. Experiments conducted on specimens of various V-Cr-Ti alloys exposed to pH 2 levels of 0.01 and 3 x 10 -6 torr showed negligible effect of H 2 on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed to 1.0 torr H 2 pressure. Preliminary data from sequential exposures of the materials to low-pO 2 and several low-pH 2 environments did not reveal an adverse effect on the maximum engineering stress or on uniform and total elongation. Further, tests in H 2 environments on specimens annealed at different temperatures showed that grain-size variation by a factor of ∼2 had little or no effect on tensile properties

Electrically insulating films deposited on V-4%Cr-4%Ti by reactive CVD

International Nuclear Information System (INIS)

Park, J.H.

1998-04-01

In the design of liquid-metal blankets for magnetic fusion reactors, corrosion resistance of structural materials and the magnetohydrodynamic forces and their influence on thermal hydraulics and corrosion are major concerns. Electrically insulating CaO films deposited on V-4%Cr-4%Ti exhibit high-ohmic insulator behavior even though a small amount of vanadium from the alloy become incorporated into the film. However, when vanadium concentration in the film is > 15 wt.%, the film becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. The objective of this study is to evaluate electrically insulating films that were deposited on V-4%Cr-4%Ti by a reactive chemical vapor deposition (CVD) method. To this end, CaO and Ca-V-O coatings were produced on vanadium alloys by CVD and by a metallic-vapor process to investigate the electrical resistance of the coatings. The authors found that the Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film > 0.9, and semiconductor or conductor behavior when R 0.98 were exposed in liquid lithium. Based on these studies, they conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating

Effect of time and temperature on grain size of V and V-Cr-Ti alloys

International Nuclear Information System (INIS)

Natesan, K.; Rink, D.L.

1996-01-01

Grain growth studies were conducted to evaluate the effect of time and temperature on the grain size of pure V, V-4 wt.%Cr-4 wt.%Ti, and V-5 wt.%Cr-5 wt.%Ti alloys. The temperatures used in the study were 500, 650, 800, and 1000 degrees C, and exposure times ranged between 100 and ∼5000 h. All three materials exhibited negligible grain growth at 500, 650, and 800 degrees C, even after ∼5000 h. At 1000 degrees C, pure V showed substantial grain growth after only 100 h, and V-4Cr-4Ti showed growth after 2000 h, while V-5Cr-5Ti showed no grain growth after exposure for up to 2000 h

Dynamic Shear Deformation and Failure of Ti-6Al-4V and Ti-5Al-5Mo-5V-1Cr-1Fe Alloys.

Science.gov (United States)

Ran, Chun; Chen, Pengwan

2018-01-05

To study the dynamic shear deformation and failure properties of Ti-6Al-4V (Ti-64) alloy and Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, a series of forced shear tests on flat hat shaped (FHS) specimens for the two investigated materials was performed using a split Hopkinson pressure bar setup. The evolution of shear deformation was monitored by an ultra-high-speed camera (Kirana-05M). Localized shear band is induced in the two investigated materials under forced shear tests. Our results indicate that severe strain localization (adiabatic shear) is accompanied by a loss in the load carrying capacity, i.e., by a sudden drop in loading. Three distinct stages can be identified using a digital image correlation technique for accurate shear strain measurement. The microstructural analysis reveals that the dynamic failure mechanisms for Ti-64 and Ti-55511 alloys within the shear band are of a cohesive and adhesive nature, respectively.

Electrical resistivity of V-Cr-Ti alloys

Energy Technology Data Exchange (ETDEWEB)

Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

1997-04-01

Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

Dynamic globularization of a-phase in Ti6Al4V alloy during hot compression

CSIR Research Space (South Africa)

Mutombo, K

2013-12-01

Full Text Available composition dependence of the martensite start temperature (Ms) has been done for Ti-Fe, Ti-Cr, Ti-Mo, Ti-V, Ti-Nb, Ti-Zr and Ti-Al alloys [1], [2]. The beneficial effect on the formation of hexagonal-structured martensite (α′) of Al, Mn, Cr, Sn and Fe... alloying elements, has been discussed by Lin et al [4]. However, the formation of the orthorhombic-structured martensite (α′′) which is favoured by elements such as Nb, Mo, Zr, W and V (strong β stabilizers) or H (a strong β stabilizer), has been reported...

Investigation on mechanical alloying process for v-cr-ti alloys

International Nuclear Information System (INIS)

Stanciulescu, M.; Carlan, P.; Mihalache, M.; Bucsa, G.; Abrudeanu, M.; Galateanu, A.

2015-01-01

Mechanical alloying (MA) is an efficient approach for fabricating oxide-dispersion alloys and structural materials including vanadium alloys for fusion and fission application. Dissolution behaviour of the alloying elements is a key issue for optimizing the mechanical alloying process in fabricating vanadium alloys. This paper studies the MA process of V-4wt.%Cr-4wt.%Ti alloy. The outcomes of the MA powders in a planetary ball mill are reported in terms of powder particle size and morphology evolution and elemental composition. The impact of spark-plasma sintering process on the mechanically alloyed powder is analysed. An optimal set of sintering parameters, including the maximum temperature, the dwell time and the heating rate are determined. (authors)

Volatility of V15Cr5Ti fusion reactor alloy

International Nuclear Information System (INIS)

Neilson, R.M. Jr.

1986-01-01

One potential hazard from the presence of activation products in fusion facilities is accidental oxidation-driven volatility of those activation products. Scoping experiments were conducted to investigate the oxidation and elemental volatility of candidate fusion reactor alloy V15Cr5Ti as a function of time, temperature, and test atmosphere. Experiments in air and in argon carrier gases containing 10 4 to 10 1 Pa (10 -1 to 10 -4 atm) oxygen were conducted to investigate the lower oxygen partial pressure limit for the formation of a low melting point (approximately 650 0 C), high volatility, oxide layer and its formation rate. Experiments to determine the elemental volatility of alloy constituents in air at temperatures of 700 0 C to greater than 1600 0 C. Some of these volatility experiments used V15Cr5Ti that was arc-remelted to incorporate small quantities (<0.1 wt. %) of Sc and Ca. Incorporation of Sc and Ca in test specimens permitted volatility measurement of radioactive constituents present only after activation of V15Cr5Ti

Material characteristic of Ti alloy (Ti-6Al-4V)

International Nuclear Information System (INIS)

Toyoshima, Noboru

1997-03-01

In regard to material characteristic of Ti alloy (Ti-6Al-4V), the following matters are provided by experiments. 1) In high temperature permeation behavior of implanted deuterium ion (0.5keV, 6.4 x 10 18 D + ions/m 2 s, ∼760deg K), the ratio of permeation flux to incident flux ranges from 3.3 x 10 -3 at 633deg K to 4.8 x 10 -3 at 753deg K. The activation energy of permeation is 0.12eV in this temperature region above 600deg K. At temperatures below 600deg K, the permeation flux of deuterium decreases drastically and the implanted ions remain in the alloy. 2) Radioactivation analysis using 14MeV fast neutron shows that Ti-6Al-4V alloy contains higher values of principal ingredients, Al, V, Fe, than that recorded at the chemical composition of Ti alloy, and also, contains impurities with Ni, Co and Mn. 3) Fraction of about 0.095wt% H 2 were absorbed in the test specimens, and tensile strength test was carried out. Under the condition of the hydrogen pressure 50 torr and temperature ∼500degC. The results show that there is no degradation in mechanical properties for absorption of with less than 0.04wt% H 2 . The tensile strength of wilding specimens have almost the same as that without wilding. Ti alloy, as a material of vacuum vessel of nuclear fusion device, must be selected to that with less impurities, particularly Co, by radioactivation analysis, and must be used under the temperature of 200-300degC, where hydrogen absorption does not make too progress. It is considered that Ti alloy can be used with less than 0.04wt% H 2 absorption in viewpoint of material mechanical strength. (author)

Relationship of microstructure and mechanical properties for V-Cr-Ti alloys

International Nuclear Information System (INIS)

Loomis, B.A.; Gazda, J.; Nowicki, L.J.; Smith, D.L.; Danyluk, S.

1993-08-01

Relation of composition, number density, and diameter of precipitates in microstructures of unalloyed V and V-Cr-Ti alloys to the yield strength, hardness, creep stress, and ductile-brittle transition temperature (DBTT) for these materials was determined from analytical electron microscopy analyses of precipitates in these materials and from mechanical properties data. Unalloyed V and V-Cr-Ti alloys with ≤3 wt. % Ti contained VC and TI(CNO) precipitates that were coherent with the matrix. The most common precipitates in the alloys were Ti(C 1-x-y N x O y ) that were non-coherent with the matrix. The number density of non-coherent precipitates was maximum in V-3Ti and V-5Cr-3Ti alloys, and the average diameter of non-coherent precipitates was minimum in V-(1--3)Ti and V-5Cr-3Ti alloys. The increase of yield strength and hardness of V on alloying with Ti and Cr was shown to be primarily due to coherent precipitate, solute-atom misfit, and shear-modulus difference effects. The creep stress for rupture in 1000 hours was related to the number density of precipitates, whereas the DBTT was related to the volume fraction of precipitates

Grain boundary migration induced segregation in V-Cr-Ti alloys

Energy Technology Data Exchange (ETDEWEB)

Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Ohnuki, S.; Takahashi, H. [Univ. of Hokkaido (Japan)

1996-10-01

Analytical electron microscopy results are reported for a series of vanadium alloys irradiated in the HFIR JP23 experiment at 500{degrees}C. Alloys were V-5Cr-5Ti and pure vanadium which are expected to have transmuted to V-15Cr-5Ti and V-10Cr following irradiation. Analytical microscopy confirmed the expected transmutation occurred and showed redistribution of Cr and Ti resulting from grain boundary migration in V-5Cr-5Ti, but in pure V, segregation was reduced and no clear trends as a function of position near a boundary were identified.

Study on improved tribological properties by alloying copper to CP-Ti and Ti-6Al-4V alloy.

Science.gov (United States)

Wang, Song; Ma, Zheng; Liao, Zhenhua; Song, Jian; Yang, Ke; Liu, Weiqiang

2015-12-01

Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti-5Cu and Ti-6Al-4V-5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO2 counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti2Cu intermetallic compounds appeared in both Ti-5Cu and Ti-6Al-4V-5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti-5Cu and Ti-6Al-4V-5Cu alloys due to the precipitation of Ti2Cu. The results also indicated that both CP-Ti and Ti-5Cu behaved better wear resistance than Ti-6Al-4V and Ti-6Al-4V-5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti-5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti-6Al-4V and Ti-6Al-4V-5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison between PIII superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Reis, D.A.P.; Moura Neto, C.; Silva, M.M.; Ueda, M.; Oliveira, V.S.; Couto, A.A.

2009-01-01

The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of PIII superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190 deg C by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treatment of PIII and ceramic coating was submitted to creep tests at 600°C and 250 and 319 MPa under constant load mode. In the PIII treatment the samples was put in a vacuum reactor (76 x 10 -3 Pa) and implanted by nitrogen ions in time intervals between 15 and 120 minutes. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the ceramic coating on Ti-6Al-4V alloy improved its creep resistance. (author)

Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

Energy Technology Data Exchange (ETDEWEB)

Zinkle, S.J.; Alexander, D.J.; Robertson, J.P. [Oak Ridge National Lab., TN (United States)] [and others

1997-04-01

Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimens were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.

Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

Science.gov (United States)

Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

2016-05-01

Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

Osteoblast Cell Response on the Ti6Al4V Alloy Heat-Treated

Directory of Open Access Journals (Sweden)

Mercedes Paulina Chávez-Díaz

2017-04-01

Full Text Available In an effort to examine the effect of the microstructural changes of the Ti6Al4V alloy, two heat treatments were carried out below (Ti6Al4V800 and above (Ti6Al4V1050 its β-phase transformation temperature. After each treatment, globular and lamellar microstructures were obtained. Saos-2 pre-osteoblast human osteosarcoma cells were seeded onto Ti6Al4V alloy disks and immersed in cell culture for 7 days. Electrochemical assays in situ were performed using OCP and EIS measurements. Impedance data show a passive behavior for the three Ti6Al4V alloys; additionally, enhanced impedance values were recorded for Ti6Al4V800 and Ti6Al4V1050 alloys. This passive behavior in culture medium is mostly due to the formation of TiO2 during their sterilization. Biocompatibility and cell adhesion were characterized using the SEM technique; Ti6Al4V as received and Ti6Al4V800 alloys exhibited polygonal and elongated morphology, whereas Ti6Al4V1050 alloy displayed a spherical morphology. Ti and O elements were identified by EDX analysis due to the TiO2 and signals of C, N and O, related to the formation of organic compounds from extracellular matrix. These results suggest that cell adhesion is more likely to occur on TiO2 formed in discrete α-phase regions (hcp depending on its microstructure (grains.

Identification of ultra-fine Ti-rich precipitates in V-Cr-Ti alloys irradiated below 300 deg. C by using positron CDB technique

International Nuclear Information System (INIS)

Fukumoto, Ken-ichi; Matsui, Hideki; Ohkubo, Hideaki; Tang, Zheng; Nagai, Yasuyoshi; Hasegawa, Masayuki

2008-01-01

Irradiation-induced Ti-rich precipitates in V-Ti and V-4Cr-4Ti alloys are studied by TEM and positron annihilation methods (positron lifetime, and coincidence Doppler broadening (CDB)). The characteristics of small defect clusters formed in V alloys containing Ti at irradiation temperatures below 300 deg. C have not been identified by TEM techniques. Strong interaction between vacancy and Ti solute atoms for irradiated V alloys containing Ti at irradiation temperatures from 220 to 350 deg. C are observed by positron lifetime measurement. The vacancy-multi Ti solute complexes in V-alloys containing Ti are definitely identified by using CDB measurement. It is suggested that ultra-fine Ti-rich precipitates or Ti segregation at periphery of dislocation loops are formed in V alloys containing Ti at irradiation temperatures below 300 deg. C

Early evaluation of hydrogen isotopes separation by V4Cr4Ti-based sorbents at low temperatures

Energy Technology Data Exchange (ETDEWEB)

Kulsartov, Timur, E-mail: tima@physics.kz [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan); Shestakov, Vladimir; Chikhray, Yevgen; Kenzhina, Inesh; Askerbekov, Saulet [Institute of Experimental and Theoretical Physics of Kazakh National University, 050038 Almaty (Kazakhstan); Gordienko, Yuriy; Ponkratov, Yuriy; Zaurbekova, Zhanna [Institute of Atomic Energy of National Nuclear Center, 071100 Kurchatov (Kazakhstan)

2016-12-15

This paper presents the results of experiments on hydrogen isotopes sorption with V4Cr4Ti vanadium alloys from a mixture of hydrogen isotopes. The studies were carried out at temperatures of 353 K, 393 K, 423 K; and pressures of 10{sup 3}–10{sup 4} Pa in gas mixture of hydrogen isotopes. The α-phase domain of V-H (D) system was studied, where the concentration of hydrogen isotopes atoms should not exceed 0.015H (D) atoms per metal atom. The separation parameters were derived for several saturation conditions accordingly to registered time dependences of hydrogen isotopes partial pressure drop. The conclusion was made about the prospects of using vanadium alloys in hydrogen isotopes separation and purification systems.

Uniaxial creep behavior of V-4Cr-4Ti alloy

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.; Purohit, A.

2002-01-01

We are undertaking a systematic study at Argonne National Laboratory to evaluate the uniaxial creep behavior of V-Cr-Ti alloys in a vacuum environment as a function of temperature in the range of 650-800 deg. C and at applied stress levels of 75-380 MPa. Creep strain in the specimens is measured by a linear-variable-differential transducer, which is attached between the fixed and movable pull rods of the creep assembly. Strain is measured at sufficiently frequent intervals during testing to define the creep strain/time curve. A linear least-squares analysis function is used to ensure consistent extraction of minimum creep rate, onset of tertiary creep and creep strain at the onset of tertiary creep. Creep test data, obtained at 650, 700, 725 and 800 deg. C, showed power-law creep behavior. Extensive analysis of the tested specimens is conducted to establish hardness profiles, oxygen content and microstructural characteristics. The data are also quantified by the Larson-Miller approach, and correlations are developed to relate time to rupture, onset of tertiary creep, times for 1% and 2% strain, exposure temperature and applied stress

Creep behavior of plasma carburized Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Oliveira, Veronica Mara Cortez Alves de; Barboza, Miguel Justino Ribeiro; Silva, Mariane Capellari Leite da; Pinto, Catia Gisele; Suzuki, Paulo Atsushi; Machado, Joao Paulo B.

2010-01-01

This paper aims to evaluate the effect of plasma carburizing on the Ti-6Al-4V alloy submitted to creep tests. The results showed that the alloy Ti-6Al-4V had a hardness of 334 ± 18 HV. After treatment thermochemical by plasma, was observed the formation of a layer of average thickness of 1,5 μm and hardness of 809 ± 79 HV due to the presence of TiC phase identified by X-ray diffraction. The treatment increased the values of average roughness of 1,28 to 2,02 μm. The creep properties of carburized specimens were improved in comparison with those of the uncarburized Ti-6Al-4V alloy. (author)

Laser Powder Cladding of Ti-6Al-4V α/β Alloy

OpenAIRE

Samar Reda Al-Sayed Ali; Abdel Hamid Ahmed Hussein; Adel Abdel Menam Saleh Nofal; Salah Elden Ibrahim Hasseb Elnaby; Haytham Abdelrafea Elgazzar; Hassan Abdel Sabour

2017-01-01

Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resist...

Effects of combined plasma chromizing and shot peening on the fatigue properties of a Ti6Al4V alloy

Science.gov (United States)

Yu, Shouming; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing

2015-10-01

A plasma chromizing treatment was conducted on Ti6Al4V samples by employing the recently developed double glow plasma surface alloying technology. The Cr-alloyed layer consisted of four sub-layers, namely the Cr deposition, Cr2Ti, CrTi4, and Cr-Ti solid-solution layers. The local hardness and moduli were determined via nanoindentation. In addition, the fatigue properties of the samples were evaluated by using a rotating-bending fatigue machine under a given load. The results showed that the hardness or elastic moduli of the adjacent sub-layers differed significantly and the fatigue properties of the Ti6Al4V alloy deteriorated with the plasma chromizing treatment. This deterioration stemmed mainly from cracks initiated at the interfaces between the sub-layers and the microstructural changes of the substrate; these changes were induced by the high temperature used in the plasma chromizing process. However, the fatigue life of the plasma-chromized samples was increased by a shot peening post-treatment. The fatigue life of the samples resulting from this combination of treatments was slightly higher than that of the single-shot-peened Ti6Al4V substrate. In fact, the sample retaining only the Cr-Ti solid-solution layer (that is, the first three sub-layers were removed), when shot-peened, exhibited the highest fatigue life among all the tested samples; this was attributed to that sample having the highest residual compressive stress, the significant work hardening, and the good hardness to toughness balance.

Comparison between pulsed Nd:YAG laser superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Reis, A.G.; Reis, D.A.P.; Moura Neto, C.; Oliveira, H.S.; Couto, A.A.

2009-01-01

The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of pulsed Nd:YAG laser and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190 deg C by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treatment of pulsed Nd:YAG laser and ceramic coating was submitted to creep tests at 600°C and 125 at 319 MPa, under constant load mode. In the Nd:YAG pulsed laser treatment was used an environment of 40 % N and 60 % Ar, with 2.1 W of power and 10 m/s of speed. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the laser treatment on Ti-6Al-4V alloy improved its creep resistance. (author)

Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

Science.gov (United States)

Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

2005-05-01

It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. (c) 2005 Wiley Periodicals, Inc.

Tensile properties of V-Cr-Ti alloys after exposure in oxygen-containing environments

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.

1998-01-01

A systematic study was conducted to evaluate the oxidation kinetics of V-4Cr-4Ti (44 alloy) and V-5Cr-5Ti alloys (55 alloy) and to establish the role of oxygen ingress on the tensile behavior of the alloys at room temperature and at 500 C. The oxidation rate of the 44 alloy is slightly higher than that of the 55 alloy. The oxidation process followed parabolic kinetics. Maximum engineering stress for 55 alloy increased with an increase in oxidation time at 500 C. The maximum stress values for 55 alloy were higher at room temperature than ta 500 C for the same oxidation treatment. Maximum engineering stresses for 44 alloy were substantially lower than those for 55 alloy in the same oxidation ∼500 h exposure in air at 500 C; the same values were 4.8 and 6.1%, respectively, at 500 C after ∼2060 h oxidation in air at 500 C. Maximum engineering stress for 44 alloy at room temperature was 421.6--440.6 MPa after ∼250 h exposure at 500 C in environments with a pO 2 range of 1 x 10 -6 to 760 torr. The corresponding uniform and total elongation values were 11--14.4% and 14.5--21.7%, respectively. Measurements of crack depths in various specimens showed that depth is independent of pO 2 in the preexposure environment and was of 70--95 microm after 250--275 h exposure at 500 C

Microstructure and mechanical properties of Ti-Zr-Cr biomedical alloys.

Science.gov (United States)

Wang, Pan; Feng, Yan; Liu, Fengchao; Wu, Lihong; Guan, Shaokang

2015-06-01

The Ti-15Zr-xCr (0≤x≤10, wt.%) alloys were investigated to develop new biomedical materials. It was found that the phase constitutions and mechanical properties strongly depended on the Cr content. The Ti-15Zr alloy was comprised of α' phase and a small fraction of β phase was detected with adding 1wt.% Cr. With addition of 5wt.% or more, the β phase was completely retained. In addition, the ω phase was detected in the Ti-15Zr-5Cr alloy and Ti-15Zr-7Cr alloy which exhibited the highest compressive Young's modulus and the lowest ductility. On the other hand, all the Ti-15Zr-xCr alloys without ω phase exhibited high microhardness, high yield strength and superior ductility. Furthermore, the elastic energy of Ti-15Zr-10Cr alloy (5.89MJ/m(3)) with only β phase and that of Ti-15Zr-3Cr alloy (4.04MJ/m(3)) with α' phase and small fraction of β phase was higher than the elastic energy of c.p. Ti (1.25MJ/m(3)). This study demonstrated that Ti-15Zr-3Cr alloy and Ti-15Zr-10Cr alloy with superior mechanical properties are potential materials for biomedical applications. Copyright © 2015. Published by Elsevier B.V.

Alloying behavior and deformation twinning in a CoNiFeCrAl0.6Ti0.4 high entropy alloy processed by spark plasma sintering

International Nuclear Information System (INIS)

Fu, Zhiqiang; Chen, Weiping; Fang, Sicong; Zhang, Dayue; Xiao, Huaqiang; Zhu, Dezhi

2013-01-01

Highlights: ► CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been synthesized via MA and SPS. ► Deformation twinning possibly occurred during MA or SPS. ► This alloy exhibits excellent mechanical properties. ► The fracture mechanism of this alloy is intergranular fracture and plastic fracture. -- Abstract: Inequi-atomic CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been designed and fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Alloying behavior, microstructure, phase evolution and mechanical properties of CoNiFeCrAl 0.6 Ti 0.4 alloy were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM), as well as by an Instron testing system. During MA, a supersaturated solid solution consisting of a FCC phase and a metastable BCC phase was formed. Two FCC phases (named FCC1 and FCC2) and a new BCC phase were observed after SPS. During SPS, the metastable BCC phase transformed into the FCC2 phase and the new BCC phase. Meanwhile, the FCC1 phase was the initial FCC phase which was formed during MA. Moreover, nanoscale twins obviously presented only in partial FCC1 phase after SPS. Deformation twinning may be occurred during MA or SPS. The sintered alloy with a high relative density of 98.83% exhibits excellent comprehensive mechanical properties. The yield stress, compressive strength, compression ratio and Vickers hardness of the alloy are 2.08, 2.52 GPa, 11.5% and 573 H V , respectively. The fracture mechanism of CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy is mainly performed at intergranular fracture and plastic fracture mode

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

Science.gov (United States)

Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

2013-12-01

The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

Oxidation performance of V-Cr-Ti alloys

International Nuclear Information System (INIS)

Natesan, K.; Uz, M.

2000-01-01

Vanadium-base alloys are being considered as candidates for the first wall in advanced V-Li blanket concepts in fusion reactor systems. However, a primary deterrent to the use of these alloys at elevated temperatures is their relatively high affinity for interstitial impurities, i.e., O, N, H, and C. The authors conducted a systematic study to determine the effects of time, temperature, and oxygen partial pressure (pO 2 ) in the exposure environment on O uptake, scaling kinetics, and scale microstructure in V-(4--5) wt.% Cr-(4--5) wt.% Ti alloys. Oxidation experiments were conducted on the alloys at pO 2 in the range of 5 x 10 -6 -760 torr (6.6 x 10 -4 -1 x 10 5 Pa) at several temperatures in the range of 350--700 C. Models that describe the oxidation kinetics, oxide type and thickness, alloy grain size, and depth of O diffusion in the substrate of the two alloys were determined and compared. Weight change data were correlated with time by a parabolic relationship. The parabolic rate constant was calculated for various exposure conditions and the temperature dependence of the constant was described by an Arrhenius relationship. The results showed that the activation energy for the oxidation process is fairly constant at pO 2 levels in the range of 5 x 10 -6 -0.1 torr. The activation energy calculated from data obtained in the air tests was significantly lower, whereas that obtained in pure-O tests (at 760 torr) was substantially higher than the energy obtained under low-pO 2 conditions. The oxide VO 2 was the predominant phase that formed in both alloys when exposed to pO 2 levels of 6.6 x 10 -4 to 0.1 torr. V 2 O 5 was the primary phase in specimens exposed to air and to pure O 2 at 760 torr. The implications of the increased O concentration are increased strength and decreased ductility of the alloy. However, the strength of the alloy was not a strong function of the O concentration of the alloy, but an increase in O concentration did cause a substantial decrease

Precision casting of Ti-15V-3Cr-3Al-3Sn alloy setting

OpenAIRE

Nan Hai; Liu Changkui; Huang Dong

2008-01-01

In this research, Ti-15V-3Cr-3Al-3Sn alloy ingots were prepared using ceramic mold and centrifugal casting. The Ti-15V-3Cr-3Al-3Sn setting casting, for aeronautic engine, with 1.5 mm in thickness was manufactured. The alloy melting process, precision casting process, and problems in casting application were discussed. Effects of Hot Isostatic Pressing and heat treatment on the mechanical properties and microstructure of the Ti-15V-3Cr-3Al-3Sn alloy were studied.

In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

Science.gov (United States)

Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

2014-01-01

Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. © 2013 Elsevier Ltd. All rights reserved.

Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study

International Nuclear Information System (INIS)

Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

2013-01-01

The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5–216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO 2  phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets. (paper)

Key improvements in machining of Ti6al4v alloy: A review

Science.gov (United States)

Katta, Sivakoteswararao; Chaitanya, G.

2017-07-01

Now a days the use of ti-6al-4v alloy is high in demand in many industries like aero space, bio medical automobile, space, military etc. the production rates in the industries are not sufficient because the machiniability of ti-6al-4v is the main problem, there are several cutting tools available for metal cutting operations still there is a gap in finding the proper cutting tool material for machining of ti-6al-4v. because the properties of titanium like high heat resistant, low thermal conductivity, low weight ratio, less corrosiveness, and more many properties attracting the industrialists to use titanium as their material for their products, many researchers done the research on machininbility of ti-6al-4v by using different tool materials. but as for my literature survey there is still lot of scope is available, to find better cutting tool with techniques for machining ti-6al-4v. in this paper iam discussing the work done by various researchers on ti-6al-4v alloy with different techniques.

Three-dimensional characterization of pores in Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Márcia Regina Baldissera

2011-03-01

Full Text Available The direct three-dimensional characterization of opaque materials through serial sectioning makes possible to visualize and better quantify a material microstructure, using classical metallographic techniques coupled with computer-aided reconstruction. Titanium alloys are used as biomaterials for bone implants because of its excellent mechanical properties, biocompatibility and enhanced corrosion resistance. The Ti-6Al-4V alloy (in wt. (% with porous microstructure permits the ingrowths of new-bone tissues improving the fixation bone/implant. This is important to understand connectivity, morphology and spatial distribution of pores in microstructure. The Ti-6Al-4V alloy compacts were produced by powder metallurgy and sintered at three distinct temperatures (1250, 1400 and 1500 °C to obtain distinct microstructures in terms of residual porosity. The visualization of the reconstructed 3D microstructure provides a qualitative and quantitative analysis of the porosity of Ti6Al4V alloy (volume fraction and pore morphology.

On the Young's moduli of Ti-6Al-4V alloys

International Nuclear Information System (INIS)

Fan, Zhongyun

1993-01-01

In this paper, the authors will present an iterative approach to Young's modulus of multi-phase composites developed by Fan et al. The iterative approach will then be applied to Ti-6Al-4V alloys to predict their effective Young's moduli. It is hoped that the theoretical predictions will offer a quantitative explanation to the peculiar shape of the E c -f β curve and will shed some light on controlling the Young's moduli of Ti-6Al-4V alloys by choosing the proper heat treatment procedure

Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

Science.gov (United States)

Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

2018-05-01

The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

Surface hardening of Ti-6Al-4V alloy by hydrogenation

International Nuclear Information System (INIS)

Wu, T.I.; Wu, J.K.

1991-01-01

Thermochemical processing is an advanced method to enhance the fabricability and mechanical properties of titanium alloys. In this process hydrogen is added to the titanium alloy as a temporary alloying element. Hydrogen addition lowers the β transus temperature of titanium alloy and stabilizes the β phase. The increased amount of β phase in hydrogen-modified titanium alloys reduces the grain growth rate during eutectoid β → α + hydride reaction. Hydrogen was added to the titanium alloy by holding it at a relatively high temperature in a hydrogen gaseous environment in previous studies. Pattinato reported that Ti-6Al-4V alloy can react with hydrogen gas at ambient temperature and cause a serious hydrogen embrittlement problem. The hydrogen must be removed to a low allowable concentration in a vacuum system after the hydrogenation process. The present study utilized an electrochemical technique to dissolve hydrogen into titanium alloy to replace the hydrogen environment in thermochemical processing. In this paper microstructures and hardnesses of this new processed Ti-6Al-4V alloy are reported

High performance Ti-6Al-4V + TiC alloy by blended elemental powder metallurgy

International Nuclear Information System (INIS)

Fujii, H.; Yamazaki, T.; Horiya, T.; Takahashi, K.

1993-01-01

The blended elemental powder metallurgy (BE) of titanium alloys is one of the most cost saving technologies, in which the blending of titanium powder and alloying element powders (or master alloy powders), precise compaction at room temperature, and consolidation are conducted in turn. In addition to some economical and material saving advantages, the BE has a noteworthy feature, that is, the synthesis of special alloy systems which are difficult to be produced by the ingot metallurgy. A particle or fiber reinforced metal matrix composite (MMC) is one of the examples, and the addition of TiC particles to the extensively used Ti-6Al 4V has succeeded in obtaining higher tensile strength, Young's modulus, and elevated temperature properties. However, the raising up of some properties sometimes deteriorates other ones in MMC, and it often prevents the practical use. In this research work, the improvement of tensile ductility and fatigue properties of Ti-6Al-4V+TiC alloys without lowering other mechanical properties is aimed through the microstructural control

Neutron irradiation effect on the strength of jointed Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Ishiyama, Shintaro; Miya, Naoyuki

2002-01-01

In order to investigate applicability of Ti alloy to large scaled structural material for fusion reactors, irradiation effect on the mechanical properties of Ti-6Al-4V alloy and its TIG welded material was investigated after neutron irradiation (temperature: 746-788K, fluence: 2.8 x 10 23 n/m 2 (>0.18 MeV). The following results were obtained. (1) Irradiated Ti alloy shows about 20-30% increase of its tensile strength and large degradation of fracture elongation, comparing with those of unirradiated Ti alloy. (2) TIG welded material behaves as Ti alloy in its tensile test, however, shows 30% increase of area reduction in 373-473K, whereas 1/2 degradation of area reduction over 600K. (3) Irradiated TIG welded material behaves heavier embrittlement than that of irradiated Ti alloy. (4) Charpy impact properties of un- and irradiated Ti alloys shift to ductile from brittle fracture and transition temperature shift, ΔT was estimated as about 100K. (5) Remarkable increase of hardness was found, especially in HAZ of TIG welded material after irradiation. (author)

Thermo-mechanical treatment of low-cost alloy Ti-4.5Al-6.9Cr-2.3Mn and microstructure and mechanical characteristics

Science.gov (United States)

Chen, Guangyao; Kang, Juyun; Wang, Shusen; Wang, Shihua; Lu, Xionggang; Li, Chonghe

2018-04-01

In this study, the thermo-mechanical treatment process for low-cost Ti-4.5Al-6.9Cr-2.3Mn alloy were designed on the basis of assessment of Ti-Al-Cr-Mn thermodynamic system. The microstructure and mechanical properties of Ti-4.5Al-6.9Cr-2.3Mn forging and sheet were investigated by using the OM, SEM and universal tensile testing machine. The results show that both the forging and sheet were consisted of α + β phase, which is consistent with the expectation, and no element Cr and Mn existed in the grain boundaries of the sheet after quenching, and the C14 laves phase was not detected. The average ultimate tensile strength (σ b), 0.2% proof strength (σ 0.2) and elongation (EI) of alloy sheet after quenching can reach 1059 MPa, 1051 MPa and 24.6 Pct., respectively. Moreover, the average ultimate tensile strength of Ti-4.5Al-6.9Cr-2.3Mn forgings can reach 1599 MPa and the average elongation can reach 11.2 Pct., and a more excellent property of Ti-4.5Al-6.9Cr-2.3Mn forging is achieved than that of TC4 forging. It provides a theoretical support for further developing this low-cost alloy.

A physically based constitutive model for a V-4Cr-4Ti alloy

International Nuclear Information System (INIS)

Donahue, E.G.; Odette, G.R.; Lucas, G.E.

2000-01-01

A constitutive model for low-to-intermediate temperatures, strains, and strain rates is developed for the program heat of V-4Cr-4Ti. The basic form of the model is derived from more general dislocation-based models of yield stress and strain hardening. The physically based forms are fit to a database derived from tensile tests carried out over a wide range of temperatures and strain rates. Yield and post-yield strain-hardening contributions to the flow stress are additive. The yield stress has both thermally activated and athermal components. The former is described by a two-mechanism activated dislocation slip model, with contributions that appear to arise from both lattice friction (at lower temperatures) and dislocation pinning by interstitial impurities (at higher temperatures). The yield stress data can be correlated using a strain rate-compensated temperature. The model uses a temperature-weighted average of the two mechanisms. Post-yield strain hardening was found to be approximately athermal. Strain hardening is fit to a two-component modified Voce-type saturating flow stress model. The constitutive model is also used to determine the flow stability limits as estimates of uniform tensile strains. The relatively compact, but mechanism-based, semi-empirical model has a number of both fundamental and practical advantages that are briefly outlined

Microstructure evolution and grain refinement of Ti-6Al-4V alloy by laser shock processing

Energy Technology Data Exchange (ETDEWEB)

Ren, X.D., E-mail: renxd@mail.ujs.edu.cn [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang, 212013 (China); Zhou, W.F.; Liu, F.F.; Ren, Y.P. [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China); Yuan, S.Q. [Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang, 212013 (China); Ren, N.F.; Xu, S.D.; Yang, T. [Department of Mechanical Engineering, Jiangsu University, Zhenjiang, 212013 (China)

2016-02-15

Graphical abstract: The grain refinement process of Ti-6Al-4V alloy under LSP: (a) LDD in original grains; (b) Dislocations in β phase; (c) DTIs in α phase; (d) DTs transform into DCs; (e) DWs develop into sub-GBs; (f) GR accomplishes. - Highlights: • LSP could repair the surface defects and reduce the surface roughness. • Microstructure evolution of α phase in Ti-6Al-4V alloy processed by LSP is distinct from β phase. • Multidirectional twin intersections and subgrain boundaries are the main mechanism of grain refinement of Ti-6Al-4V alloy. • Grain refinement process of the Ti-6Al-4V alloy was illustrated. - Abstract: Microstructure evolution and grain refinement of Ti-6Al-4V alloy after laser shock processing (LSP) are systematically investigated in this paper. Laser shock waves were induced by a Q-switched Nd:YAG laser system operated with a wave-length of 1064 nm and 10 ns pulse width. The microstructures of LSP samples were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). Present results indicate that the surface hardness of samples subjected to LSP impacts has significantly improved. Multidirectional twin intersections and dislocation movements lead to grain subdivision in α phase with ultra-high plastic deformation. High-density dislocations are found in β phase. Multidirectional twin intersections and division of sub-grain boundaries play an important role in the grain refinement of Ti-6Al-4V alloy under LSP loading conditions.

Evaluating electrically insulating films deposited on V-4% Cr-4% Ti by reactive CVD

Energy Technology Data Exchange (ETDEWEB)

Park, J.H.; Cho, W.D. [Argonne National Lab., IL (United States)

1997-04-01

Previous CaO coatings on V-4%Cr-4%Ti exhibited high-ohmic insulator behavior even though a small amount of vanadium from the alloy was incorporated in the coating. However, when the vanadium concentration in the coatings is > 15 wt%, the coating becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. To explore this situation, CaO and Ca-V-O coatings were produced on vanadium alloys by chemical vapor deposition (CVD) and by a metallic-vapor process to investigate the electrical resistance of the coatings. Initially, the vanadium alloy specimens were either charged with oxygen in argon that contained trace levels of oxygen, or oxidized for 1.5-3 h in a 1% CO-CO{sub 2} gas mixture or in air to form vanadium oxide at 625-650{degrees}C. Most of the specimens were exposed to calcium vapor at 800-850{degrees}C. Initial and final weights were obtained to monitor each step, and surveillance samples were removed for examination by optical and scanning electron microscopy and electron-energy-dispersive and X-ray diffraction analysis; the electrical resistivity was also measured. The authors found that Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film was > 0.9, and semiconductor or conductor behavior for R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, the authors conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.

Preliminary study on the corrosion resistance, antibacterial activity and cytotoxicity of selective-laser-melted Ti6Al4V-xCu alloys.

Science.gov (United States)

Guo, Sai; Lu, Yanjin; Wu, Songquan; Liu, Lingling; He, Mengjiao; Zhao, Chaoqian; Gan, Yiliang; Lin, Junjie; Luo, Jiasi; Xu, Xiongcheng; Lin, Jinxin

2017-03-01

In this study, a series of Cu-bearing Ti6Al4V-xCu (x=0, 2, 4, 6wt%) alloys (shorten by Ti6Al4V, 2C, 4C, and 6C, respectively.) with antibacterial function were successfully fabricated by selective laser melting (SLM) technology with mixed spherical powders of Cu and Ti6Al4V for the first time. In order to systematically investigate the effects of Cu content on the microstructure, phase constitution, corrosion resistance, antibacterial properties and cytotoxicity of SLMed Ti6Al4V-xCu alloys, experiments including XRD, SEM-EDS, electrochemical measurements, antibacterial tests and cytotoxicity tests were conducted with comparison to SLMed Ti6Al4V alloy (Ti6Al4V). Microstructural observations revealed that Cu had completely fused into the Ti6Al4V alloy, and presented in the form of Ti 2 Cu phase at ambient temperature. With Cu content increase, the density of the alloy gradually decreased, and micropores were obviously found in the alloy. Electrochemical measurements showed that corrosion resistance of Cu-bearing alloys were stronger than Cu-free alloy. Antibacterial tests demonstrated that 4C and 6C alloys presented strong and stable antibacterial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) compared to the Ti6Al4V and 2C alloy. In addition, similar to the Ti6Al4V alloy, the Cu-bearing alloys also exerted good cytocompatibility to the Bone Marrow Stromal Cells (BMSCs) from Sprague Dawley (SD) rats. Based on those results, the preliminary study verified that it was feasible to fabricated antibacterial Ti6Al4V-xCu alloys direct by SLM processing mixed commercial Ti6Al4V and Cu powder. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and tribological properties of self-lubricating TiO2/graphite composite coating on Ti6Al4V alloy

International Nuclear Information System (INIS)

Mu, Ming; Zhou, Xinjian; Xiao, Qian; Liang, Jun; Huo, Xiaodi

2012-01-01

Highlights: ► A TiO 2 /graphite composite coating is produced on Ti alloy by one-step PEO process. ► The TiO 2 /graphite composite coating exhibits excellent self-lubricating behavior. ► The self-lubricating composite coating improves the wear resistance by comparison to the conventional PEO coating. - Abstract: One-step plasma electrolytic oxidation (PEO) process in a graphite-dispersed phosphate electrolyte was used to prepare a graphite-containing oxide composite coating on Ti6Al4V alloy. The composition and microstructure of the oxide coatings produced in the phosphate electrolytes with and without addition of graphite were analyzed by X-ray diffractometer (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The tribological properties of the uncoated Ti6Al4V alloy and oxide coatings were evaluated using a reciprocating ball-on-disk tribometer. Results showed that the graphite-containing oxide composite coating can be successfully produced on Ti6Al4V alloy in the graphite-dispersed phosphate electrolyte using PEO process. The graphite-containing oxide composite coating registered much lower friction coefficient and wear rate than the uncoated Ti6Al4V alloy and the oxide coating without graphite under dry sliding condition, exhibiting excellent self-lubricating property.

Microstructure and deformation behavior of Ti-6Al-4V alloy by high-power laser solid forming

International Nuclear Information System (INIS)

Ren, Y.M.; Lin, X.; Fu, X.; Tan, H.; Chen, J.; Huang, W.D.

2017-01-01

This work investigated the microstructure and tensile deformation behavior of Ti-6Al-4V alloy fabricated using a high-power laser solid forming (LSF) additive manufacturing. The results show that the post-fabricated heat-treated microstructure consists of coarse columnar prior-β grains (630–1000 μm wide) and α-laths (5–9 μm) under different scanning velocities (900 and 1500 mm/min), which caused large elongation (∼18%) superior to the conventional laser additive manufacturing Ti-6Al-4V alloy. The deformation behavior of the LSF Ti-6Al-4V alloy was investigated using in situ tensile test scanning electron microscopy. The results show that shear-bands appeared along the α/β interface and slip-bands occurred within the α-laths, which lead to cracks decaying in a zigzag-pattern in the LSF Ti-6Al-4V alloy with basket-weave microstructure. These results demonstrate that the small columnar prior-β grains and fine basket-weave microstructure exhibiting more α/β interfaces and α-laths can disperse the load and resist the deformation in the LSF Ti-6Al-4V components. In addition, a modified microstructure selection map of the LSF Ti-6Al-4V alloy was established, which can reasonably predict the microstructure evolution and relative grain size in the LSF process.

French investigation of a new V-4Cr-4Ti grade: CEA-J57 - Fabrication and microstructure

Energy Technology Data Exchange (ETDEWEB)

Duquesnes, Vincent; Guilbert, Thomas [CEA Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif Sur Yvette (France); Le Flem, Marion, E-mail: marion.leflem@cea.fr [CEA Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif Sur Yvette (France)

2012-07-15

In the scope of the development of structural materials for application in future fast neutron fission reactors, a V-4Cr-4Ti alloy, which is the reference alloy for the first wall/blanket in lithium fusion reactor, was fabricated. After vacuum arc melting of the starting ingot of 30 kg, 7 mm-thick plates were processed by forging and cold rolling down to 54% thickness reduction with intermediate heat treatment at 1050 Degree-Sign C. The pollution by interstitial impurities such as O, N and C was well controlled and was quite comparable to previous grades by US and Japan - O: 290 mass ppm, C: 70 mass ppm, N: 110 mass ppm. An additional cold-rolling was achieved on a small specimen to get a reduction in thickness of 87%. The recrystallization was investigated through heat treatments between 600 Degree-Sign C and 1200 Degree-Sign C. Hardness measurement on annealed samples suggested the recrystallization to occur around 800 Degree-Sign C for 54% thickness reduction and at a lower temperature for 87% thickness reduction. The minimum hardness was obtained after annealing at 950-1000 Degree-Sign C, the microstructure being fully recrystallized and the hardness isotropic. Above this temperature, hardness increase was significant. Large Ti-rich precipitates (500 nm) formed during forging and oriented along the rolling direction were easily observed but, on the contrary to previous studies, no small Ti-(O,C) precipitates could be detected.

Study on improved tribological properties by alloying copper to CP-Ti and Ti–6Al–4V alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, Song [Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Ma, Zheng [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Song, Jian [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Yang, Ke [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

2015-12-01

Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti–5Cu and Ti–6Al–4V–5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO{sub 2} counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti{sub 2}Cu intermetallic compounds appeared in both Ti–5Cu and Ti–6Al–4V–5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti–5Cu and Ti–6Al–4V–5Cu alloys due to the precipitation of Ti{sub 2}Cu. The results also indicated that both CP-Ti and Ti–5Cu behaved better wear resistance than Ti–6Al–4V and Ti–6Al–4V–5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti–5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti–6Al–4V and Ti–6Al–4V–5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types. - Highlights: • Ti–5Cu and Ti–6Al–4V–5Cu alloys were fabricated with Cu additive. • Precipitations of Ti{sub 2}Cu intermetallic compounds appeared after alloying Cu. • The precipitation of Ti{sub 2}Cu improved both friction and wear resistance. • Plowing was the dominant material removal force with severe plowing phenomenon. • Different dominant and secondary wear mechanisms appeared with different hardness.

Molybdeno-Aluminizing of Powder Metallurgy and Wrought Ti and Ti-6Al-4V alloys by Pack Cementation process

International Nuclear Information System (INIS)

Tsipas, Sophia A.; Gordo, Elena

2016-01-01

Wear and high temperature oxidation resistance of some titanium-based alloys needs to be enhanced, and this can be effectively accomplished by surface treatment. Molybdenizing is a surface treatment where molybdenum is introduced into the surface of titanium alloys causing the formation of wear-resistant surface layers containing molybdenum, while aluminizing of titanium-based alloys has been reported to improve their high temperature oxidation properties. Whereas pack cementation and other surface modification methods have been used for molybdenizing or aluminizing of wrought and/or cast pure titanium and titanium alloys, such surface treatments have not been reported on titanium alloys produced by powder metallurgy (PM). Also a critical understanding of the process parameters for simultaneous one step molybdeno-aluminizing of titanium alloys by pack cementation and the predominant mechanism for this process have not been reported. The current research work describes the surface modification of titanium and Ti-6Al-4V prepared by PM by molybdeno-aluminizing and analyzes thermodynamic aspects of the deposition process. Similar coatings are also deposited to wrought Ti-6Al-4V and compared. Characterization of the coatings was carried out using scanning electron microscopy and x-ray diffraction. For both titanium and Ti-6Al-4V, the use of a powder pack containing ammonium chloride as activator leads to the deposition of molybdenum and aluminium into the surface but also introduces nitrogen causing the formation of a thin titanium nitride layer. In addition, various titanium aluminides and mixed titanium aluminium nitrides are formed. The appropriate conditions for molybdeno-aluminizing as well as the phases expected to be formed were successfully determined by thermodynamic equilibrium calculations. - Highlights: •Simultaneous co-deposition of Mo-Al onto powder metallurgy and wrought Ti alloy •Thermodynamic calculations were used to optimize deposition conditions

Molybdeno-Aluminizing of Powder Metallurgy and Wrought Ti and Ti-6Al-4V alloys by Pack Cementation process

Energy Technology Data Exchange (ETDEWEB)

Tsipas, Sophia A., E-mail: stsipas@ing.uc3m.es; Gordo, Elena

2016-08-15

Wear and high temperature oxidation resistance of some titanium-based alloys needs to be enhanced, and this can be effectively accomplished by surface treatment. Molybdenizing is a surface treatment where molybdenum is introduced into the surface of titanium alloys causing the formation of wear-resistant surface layers containing molybdenum, while aluminizing of titanium-based alloys has been reported to improve their high temperature oxidation properties. Whereas pack cementation and other surface modification methods have been used for molybdenizing or aluminizing of wrought and/or cast pure titanium and titanium alloys, such surface treatments have not been reported on titanium alloys produced by powder metallurgy (PM). Also a critical understanding of the process parameters for simultaneous one step molybdeno-aluminizing of titanium alloys by pack cementation and the predominant mechanism for this process have not been reported. The current research work describes the surface modification of titanium and Ti-6Al-4V prepared by PM by molybdeno-aluminizing and analyzes thermodynamic aspects of the deposition process. Similar coatings are also deposited to wrought Ti-6Al-4V and compared. Characterization of the coatings was carried out using scanning electron microscopy and x-ray diffraction. For both titanium and Ti-6Al-4V, the use of a powder pack containing ammonium chloride as activator leads to the deposition of molybdenum and aluminium into the surface but also introduces nitrogen causing the formation of a thin titanium nitride layer. In addition, various titanium aluminides and mixed titanium aluminium nitrides are formed. The appropriate conditions for molybdeno-aluminizing as well as the phases expected to be formed were successfully determined by thermodynamic equilibrium calculations. - Highlights: •Simultaneous co-deposition of Mo-Al onto powder metallurgy and wrought Ti alloy •Thermodynamic calculations were used to optimize deposition conditions

Tensile properties of aluminized V-5Cr-5Ti alloy after exposure in air environment

Energy Technology Data Exchange (ETDEWEB)

Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

1997-08-01

The objectives of this task are to (a) develop procedures to modify surface regions of V-Cr-Ti alloys in order to minimize oxygen uptake by the alloys when exposed to environments that contain oxygen, (b) evaluate the oxygen uptake of the surface-modified V-Cr-Ti alloys as a function of temperature an oxygen partial pressure in the exposure environment, (c) characterize the microstructures of oxide scales and oxygen trapped at the grain boundaries of the substrate alloys, and (d) evaluate the influence of oxygen uptake on the tensile properties of the modified alloys at room and elevated temperatures.

Tribocorrosion Study of Ordinary and Laser-Melted Ti6Al4V Alloy

Directory of Open Access Journals (Sweden)

Danillo P. Silva

2016-10-01

Full Text Available Titanium alloys are used in biomedical implants, as well as in other applications, due to the excellent combination of corrosion resistance and mechanical properties. However, the tribocorrosion resistance of titanium alloy is normally not satisfactory. Therefore, surface modification is a way to improve this specific performance. In the present paper, laser surface-modified samples were tested in corrosion and pin-on-disk tribocorrosion testing in 0.90% NaCl under an average Hertzian pressure of 410 MPa against an alumina sphere. Laser-modified samples of Ti6Al4V were compared with ordinary Ti6Al4V alloy. Electrochemical impedance showed higher modulus for laser-treated samples than for ordinary Ti6Al4V ones. Moreover, atomic force microscopy revealed that laser-treated surfaces presented less wear than ordinary alloy for the initial exposure. For a further exposure to wear, i.e., when the wear depth is beyond the initial laser-affected layer, both materials showed similar corrosion behavior. Microstructure analysis and finite element method simulations revealed that the different behavior between the initial and the extensive rubbing was related to a fine martensite-rich external layer developed on the irradiated surface of the fusion zone.

The machinability of cast titanium and Ti-6Al-4V.

Science.gov (United States)

Ohkubo, C; Watanabe, I; Ford, J P; Nakajima, H; Hosoi, T; Okabe, T

2000-02-01

This study investigated the machinability (ease of metal removal) of commercially pure (CP) titanium and Ti-6Al-4V alloy. Both CP Ti and Ti-6Al-4V were cast into magnesia molds. Two types of specimens (with alpha-case and without alpha-case) were made for CP Ti and Ti-6Al-4V. Machinability (n = 5) was evaluated as volume loss (mm3) by cutting/grinding the 3.0 mm surface using fissure burs and silicon carbide (SiC) under two machining conditions: (1) two machining forces (100 or 300 gf) at two rotational speeds (15000 or 30000 rpm) for 1 min, and (2) constant machining force of 100 gf and rotational speed of 15000 rpm for 1, 2, 5, 10, and 30 min. As controls, conventionally cast Co-Cr and Type IV gold alloys were evaluated in the same manner as the titanium. When fissure burs were used, there was a significant difference in the machinability between CP titanium with alpha-case and without alpha-case. On the other hand, there was no appreciable difference in the amount of metal removed for each tested metal when using the SiC points.

Effects of irradiation at low temperature on V-4Cr-4Ti

International Nuclear Information System (INIS)

Alexander, D.J.; Snead, L.L.; Zinkle, S.J.

1996-01-01

Irradiation at low temperatures (100 to 275 degrees C) to 0.5 dpa causes significant embrittlement and changes in the subsequent room temperature tensile properties of V-4Cr-4Ti. The yield strength and microhardness at room temperature increase with increasing irradiation temperature. The tensile flow properties at room temperature show large increases in strength and a complete loss of work hardening capacity with no uniform ductility. Embrittlement, as measured by an increase in the ductile-to-brittle transition temperature, increases with increasing irradiation temperature, at least up to 275 degrees C. This embrittlement is not due to pickup of O or other interstitial solutes during the irradiation

Effects of irradiation at low temperature on V-4Cr-4Ti

Energy Technology Data Exchange (ETDEWEB)

Alexander, D.J.; Snead, L.L.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States)] [and others

1996-10-01

Irradiation at low temperatures (100 to 275{degrees}C) to 0.5 dpa causes significant embrittlement and changes in the subsequent room temperature tensile properties of V-4Cr-4Ti. The yield strength and microhardness at room temperature increase with increasing irradiation temperature. The tensile flow properties at room temperature show large increases in strength and a complete loss of work hardening capacity with no uniform ductility. Embrittlement, as measured by an increase in the ductile-to-brittle transition temperature, increases with increasing irradiation temperature, at least up to 275{degrees}C. This embrittlement is not due to pickup of O or other interstitial solutes during the irradiation.

Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

Science.gov (United States)

Wang, Yaping; Lou, Jin; Zeng, Lilan; Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin; Zhao, Ying; Zhang, Rongfa

2017-08-01

In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP2O7 as well as some OH- groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

Tribological behavior of Ti-6Al-4V and Ti-6Al-7Nb Alloys for Total Hip Prosthesis

Directory of Open Access Journals (Sweden)

Mamoun Fellah

2014-01-01

Full Text Available The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests consisted of measuring the weight loss and the friction coefficient of samples. The oscillating friction and wear tests have been carried out in ambient with oscillating tribotester in accordance with standards ISO 7148, ASTM G99-95a, and ASTM G133-95 under different conditions of normal loads (3, 6, and 10 N and sliding speeds (1, 15, and 25 mm·s−1. As counter pairs, a 100Cr6 steel ball with 10 mm in diameter was used. Results show that the two alloys had similar friction and wear performance, although their grain structures and compositions are different. Occurrence of large frictional occurred, is probably caused by formation and periodic, localized fracture of a transfer layer. Higher friction with larger fluctuation and higher wear rate was observed at the higher siding speed. The Ti-6Al-4V wear mechanism transforms from ploughing and peeling off wear at low sliding speed to plastic deformation and adhesive wear.

Thermophysical Properties of Solid and Liquid Ti-6Al-4V (TA6V) Alloy

Science.gov (United States)

Boivineau, M.; Cagran, C.; Doytier, D.; Eyraud, V.; Nadal, M.-H.; Wilthan, B.; Pottlacher, G.

2006-03-01

Ti-6Al-4V (TA6V) titanium alloy is widely used in industrial applications such as aeronautic and aerospace due to its good mechanical properties at high temperatures. Experiments on two different resistive pulse heating devices (CEA Valduc and TU-Graz) have been carried out in order to study thermophysical properties (such as electrical resistivity, volume expansion, heat of fusion, heat capacity, normal spectral emissivity, thermal diffusivity, and thermal conductivity) of both solid and liquid Ti-6Al-4V. Fast time-resolved measurements of current, voltage, and surface radiation and shadowgraphs of the volume have been undertaken. At TU-Graz, a fast laser polarimeter has been used for determining the emissivity of liquid Ti-6Al-4V at 684.5 nm and a differential scanning calorimeter (DSC) for measuring the heat capacity of solid Ti-6Al-4V. This study deals with the specific behavior of the different solid phase transitions (effect of heating rate) and the melting region, and emphasizes the liquid state ( T > 2000 K).

Microstructure and mechanical properties of a novel near-α titanium alloy Ti6.0Al4.5Cr1.5Mn

International Nuclear Information System (INIS)

Wang, Hong-bin; Wang, Shu-sen; Gao, Peng-yue; Jiang, Tao; Lu, Xiong-gang; Li, Chong-he

2016-01-01

Based on previous Ti-Al-Cr-Mn quaternary system thermodynamic database, a novel near-α titanium alloy Ti-6.0Al-4.5Cr-1.5Mn alloy was designed and successfully prepared by the water-cooled copper crucible. Microscopic observation showed that both as-cast and annealing status consist of α phase, which coincides with the theoretical expectation. The mechanical properties at room temperature were measured and this alloy possesses good mechanical properties, its average yield-strength reaches 1051.5 MPa and tensile-strength is up to 1091.2 MPa while its average elongation is just 8.3%. Compared with the TA15, it has better mechanical strength and worse elongation. In the new alloy Laves phase Cr 2 Ti were detected by XRD pattern and TEM, which may cause the alloy's poor plasticity.

Microstructure and mechanical properties of a novel near-α titanium alloy Ti6.0Al4.5Cr1.5Mn

Energy Technology Data Exchange (ETDEWEB)

Wang, Hong-bin [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Wang, Shu-sen; Gao, Peng-yue; Jiang, Tao [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang; Li, Chong-he [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

2016-08-30

Based on previous Ti-Al-Cr-Mn quaternary system thermodynamic database, a novel near-α titanium alloy Ti-6.0Al-4.5Cr-1.5Mn alloy was designed and successfully prepared by the water-cooled copper crucible. Microscopic observation showed that both as-cast and annealing status consist of α phase, which coincides with the theoretical expectation. The mechanical properties at room temperature were measured and this alloy possesses good mechanical properties, its average yield-strength reaches 1051.5 MPa and tensile-strength is up to 1091.2 MPa while its average elongation is just 8.3%. Compared with the TA15, it has better mechanical strength and worse elongation. In the new alloy Laves phase Cr{sub 2}Ti were detected by XRD pattern and TEM, which may cause the alloy's poor plasticity.

Design and verification of thermomechanical parameters of P/M Ti6Al4V alloy forging

Energy Technology Data Exchange (ETDEWEB)

Wojtaszek, Marek, E-mail: mwojtasz@metal.agh.edu.pl; Śleboda, Tomasz

2014-12-05

Highlights: • Thermomechanical parameters of P/M Ti6Al4V alloy processing were determined. • The use of the mixture of elemental powders allows reducing manufacturing costs. • Numerical modelling allowed to elaborate favourable parameters of forging. • The industrial trials of hot forging of P/M Ti6Al4V alloy were successful. - Abstract: This work is focused on the design of technology of forging high-quality Ti6Al4V alloy by means of powder metallurgy methods. A mixture of elemental powders, with the chemical composition of that of Ti6Al4V alloy, was used as a starting material for the investigation. Powder mixtures were fully densified by hot compaction under precisely controlled conditions. The mechanical properties of the obtained compacts were examined. The mechanical behaviour of the investigated alloy powder compacts was evaluated by compression test under various thermomechanical conditions using Gleeble simulator. The microstructure of powder compacts as well as P/M alloy samples deformed in compression tests was examined. All data obtained from the experimental tests were applied as boundary conditions for numerical simulation of forging of selected forgings. Basing on the results of both plastometric tests and simulations, thermomechanical parameters of the investigated alloy forging were determined. Designed parameters of forging technology were verified by forging trials performed in industrial conditions. The quality of the obtained forgings was examined by means of computed tomography.

Design and verification of thermomechanical parameters of P/M Ti6Al4V alloy forging

International Nuclear Information System (INIS)

Wojtaszek, Marek; Śleboda, Tomasz

2014-01-01

Highlights: • Thermomechanical parameters of P/M Ti6Al4V alloy processing were determined. • The use of the mixture of elemental powders allows reducing manufacturing costs. • Numerical modelling allowed to elaborate favourable parameters of forging. • The industrial trials of hot forging of P/M Ti6Al4V alloy were successful. - Abstract: This work is focused on the design of technology of forging high-quality Ti6Al4V alloy by means of powder metallurgy methods. A mixture of elemental powders, with the chemical composition of that of Ti6Al4V alloy, was used as a starting material for the investigation. Powder mixtures were fully densified by hot compaction under precisely controlled conditions. The mechanical properties of the obtained compacts were examined. The mechanical behaviour of the investigated alloy powder compacts was evaluated by compression test under various thermomechanical conditions using Gleeble simulator. The microstructure of powder compacts as well as P/M alloy samples deformed in compression tests was examined. All data obtained from the experimental tests were applied as boundary conditions for numerical simulation of forging of selected forgings. Basing on the results of both plastometric tests and simulations, thermomechanical parameters of the investigated alloy forging were determined. Designed parameters of forging technology were verified by forging trials performed in industrial conditions. The quality of the obtained forgings was examined by means of computed tomography

Microstructure-Tensile Properties Correlation for the Ti-6Al-4V Titanium Alloy

Science.gov (United States)

Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing; Guo, Ping

2015-04-01

Finding the quantitative microstructure-tensile properties correlations is the key to achieve performance optimization for various materials. However, it is extremely difficult due to their non-linear and highly interactive interrelations. In the present investigation, the lamellar microstructure features-tensile properties correlations of the Ti-6Al-4V alloy are studied using an error back-propagation artificial neural network (ANN-BP) model. Forty-eight thermomechanical treatments were conducted to prepare the Ti-6Al-4V alloy with different lamellar microstructure features. In the proposed model, the input variables are microstructure features including the α platelet thickness, colony size, and β grain size, which were extracted using Image Pro Plus software. The output variables are the tensile properties, including ultimate tensile strength, yield strength, elongation, and reduction of area. Fourteen hidden-layer neurons which can make ANN-BP model present the most excellent performance were applied. The training results show that all the relative errors between the predicted and experimental values are within 6%, which means that the trained ANN-BP model is capable of providing precise prediction of the tensile properties for Ti-6Al-4V alloy. Based on the corresponding relations between the tensile properties predicted by ANN-BP model and the lamellar microstructure features, it can be found that the yield strength decreases with increasing α platelet thickness continuously. However, the α platelet thickness exerts influence on the elongation in a more complicated way. In addition, for a given α platelet thickness, the yield strength and the elongation both increase with decreasing β grain size and colony size. In general, the β grain size and colony size play a more important role in affecting the tensile properties of Ti-6Al-4V alloy than the α platelet thickness.

Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

International Nuclear Information System (INIS)

Grossbeck, M.L.; Odom, R.W.

1998-06-01

The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials

STUDY OF THERMAL BEHAVIOUR ON TITANIUM ALLOYS (TI-6AL-4V

Directory of Open Access Journals (Sweden)

VASUDEVAN D

2017-08-01

Full Text Available Titanium is recognized for its strategic importance as a unique lightweight, high strength alloyed structurally efficient metal for critical, high-performance aircraft, such as jet engine and airframe components. Titanium is called as the "space age metal" and is recognized for its high strength-to-weight ratio. Today, titanium alloys are common, readily available engineered metals that compete directly with stainless steel and Specialty steels, copper alloys, nickel based alloys and composites. Titanium alloys are needed to be heat treated in order to reduce residual stress developed during fabrication and to increase the strength. Titanium (Ti-6Al-4V alloy is an alpha, beta alloy which is solution treated at a temperature of 950 ºC to attain beta phase. This beta phase is maintained by quenching and subsequent aging to increase strength. Thermal cycling process was carried out for Ti-6Al-4V specimens using forced air cooling. Heat treated titanium alloy specimen was used to carry out various tests before and after thermal cycling, The test, like tensile properties, co-efficient of thermal expansion, Microstructure, Compression test, Vickers Hardness was examined by the following test. Coefficient of Thermal expansion was measured using Dilatometer. Tensile test was carried out at room temperature using an Instron type machine. Vickers's hardness measurement was done on the same specimen as used for the microstructural observation from near the surface to the inside specimen. Compression test was carried out at room temperature using an Instron type machine. Ti‐6Al‐4V alloy is a workhorse of titanium industry; it accounts for about 60 percent of the total titanium alloy production. The high cost of titanium makes net shape manufacturing routes very attractive. Casting is a near net shape manufacturing route that offers significant cost advantages over forgings or complicated machined parts.

Laser Cladding of Ti-6Al-4V Alloy with Ti-Al2O3 Coating for Biomedical Applications

Science.gov (United States)

Mthisi, A.; Popoola, A. P. I.; Adebiyi, D. I.; Popoola, O. M.

2018-05-01

The indispensable properties of Ti-6Al-4V alloy coupled with poor tribological properties and delayed bioactivity make it a subject of interest to explore in biomedical application. A quite number of numerous coatings have been employed on titanium alloys, with aim to overcome the poor properties exhibited by this alloy. In this work, the possibility of laser cladding different ad-mixed powders (Ti - 5 wt.% Al2O3 and Ti - 8wt.% Al2O3) on Ti-6Al-4V at various laser scan speed (0.6 and 0.8 m/min) were investigated. The microstructure, phase constituents and corrosion of the resultant coatings were characterized by scanning electron microscope (SEM), Optical microscope, X-Ray diffractometer (XRD) and potentiostat respectively. The electrochemical behaviour of the produced coatings was studied in a simulated body fluid (Hanks solution). The microstructural results show that a defect free coating is achieved at low scan speed and ad-mixed of Ti-5 wt. % Al2O3. Cladding of Ti - Al2O3 improved the corrosion resistance of Ti-6Al-4V alloy regardless of varying neither scan speed nor ad-mixed percentage. However, Ti-5 wt.% Al2O3 coating produced at low scan speed revealed the highest corrosion resistance among the coatings due to better quality coating layer. Henceforth, this coating may be suitable for biomedical applications.

Layered Composite of TiC-TiB2 to Ti-6Al-4V in Graded Composition by Combustion Synthesis in High-gravity Field

International Nuclear Information System (INIS)

Huang Xuegang; Zhao Zhongmin; Zhang Long

2013-01-01

By taking combustion synthesis to prepare solidified TiB 2 matrix ceramic in high-gravity field, the layered composite of TiC-TiB 2 ceramic to Ti-6Al-4V substrate in graded composition was achieved. XRD, FESEM and EDS results showed that the bulk full-density solidified TiC-TiB 2 composite was composed of fine TiB 2 platelets, TiC irregular grains, a few of α-Al 2 O 3 inclusions and Cr alloy phases, and α'-Ti phases alternating with Ti-enriched carbides constituted the matrix of the joint in which fine TiB platelets were embedded, whereas some C, B atoms were also detected at the heat-affected zone of Ti-6A1-4V substrate. The layered composite of the solidified ceramic to Ti-6Al-4V substrate in graded composition with continuous microstructure was considered a result of fused joint and inter-diffusion between liquid ceramic and surface-molten Ti alloy, followed by TiB 2 -Ti peritectic reaction and subsequent eutectic reaction in TiC-TiB-Ti ternary system.

Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

Energy Technology Data Exchange (ETDEWEB)

Wang, Yaping [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Lou, Jin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zeng, Lilan [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Xiang, Junhuai; Zhang, Shufang; Wang, Jun; Xiong, Fucheng; Li, Chenglin [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China); Zhao, Ying, E-mail: ying.zhao@siat.ac.cn [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Zhang, Rongfa, E-mail: rfzhang-10@163.com [School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330038 (China)

2017-08-01

Highlights: • Phytic acid is used as the MAO electrolyte of titanium alloys. • MAO coatings are composed of rutile, anatase, TiP{sub 2}O{sub 7} and some OH{sup −} groups. • The MAO samples present excellent in vitro cytocompatibility. - Abstract: In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP{sub 2}O{sub 7} as well as some OH{sup −} groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

A master curve-mechanism based approach to modeling the effects of constraint, loading rate and irradiation on the toughness-temperature behavior of a V-4Cr-4Ti alloy

International Nuclear Information System (INIS)

Odette, G.R.; Donahue, E.; Lucas, G.E.; Sheckherd, J.W.

1996-01-01

The influence of loading rate and constraint on the effective fracture toughness as a function of temperature [K e (T)] of the fusion program heat of V-4Cr-4Ti was measured using subsized, three point bend specimens. The constitutive behavior was characterized as a function of temperature and strain rate using small tensile specimens. Data in the literature on this alloy was also analysed to determine the effect of irradiation on K e (T) and the energy temperature (E-T) curves measured in subsized Charpy V-notch tests. It was found that V-4Cr-4Ti undergoes open-quotes normalclose quotes stress-controlled cleavage fracture below a temperature marking a sharp ductile-to-brittle transition. The transition temperature is increased by higher loading rates, irradiation hardening and triaxial constraint. Shifts in a reference transition temperature due to higher loading rates and irradiation can be reasonably predicted by a simple equivalent yield stress model. These results also suggest that size and geometry effects, which mediate constraint, can be modeled by combining local critical stressed area σ*/A* fracture criteria with finite element method simulations of crack tip stress fields. The fundamental understanding reflected in these models will be needed to develop K e (T) curves for a range of loading rates, irradiation conditions, structural size scales and geometries relying (in large part) on small specimen tests. Indeed, it may be possible to develop a master K e (T) curve-shift method to account for these variables. Such reliable and flexible failure assessment methods are critical to the design and safe operation of defect tolerant vanadium structures

Laser Powder Cladding of Ti-6Al-4V α/β Alloy

Science.gov (United States)

Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

2017-01-01

Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times. PMID:29036935

Laser Powder Cladding of Ti-6Al-4V α/β Alloy.

Science.gov (United States)

Al-Sayed Ali, Samar Reda; Hussein, Abdel Hamid Ahmed; Nofal, Adel Abdel Menam Saleh; Hasseb Elnaby, Salah Elden Ibrahim; Elgazzar, Haytham Abdelrafea; Sabour, Hassan Abdel

2017-10-15

Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD). The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm -2 . An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

Hydridation of Ti-6Al-4V

International Nuclear Information System (INIS)

Domizzi, G; Luppo, M.I; Ortiz, M; Vigna, G

2004-01-01

The production of Ti pieces or their alloys through powder metallurgy is an economical alternative that replaces the costly methods commonly used. The Ti-6AI-4V alloy is widely used in the aerospace, chemical and medical industries. The use of powder from the alloy instead of using more pure alloyed titanium powders, further simplifies the production process. The presence of V allows the phase β to stabilize at very low temperatures and both alloys alter the Ti-H equilibrium diagram. This work analyzes to what degree these effects influence the obtaining of powders from this alloy from that of hydridation and dehydridation. Although it has slower kinetics, powders can be produced in times similar to those found for grade 2 Ti since the distribution of hydrides in the sample is uniform and the material is fragile enough for concentrations of approximately 0.7 H/Ti (CW)

Investigation of laser cladding high temperature anti-wear composite coatings on Ti6Al4V alloy with the addition of self-lubricant CaF2

International Nuclear Information System (INIS)

Xiang, Zhan-Feng; Liu, Xiu-Bo; Ren, Jia; Luo, Jian; Shi, Shi-Hong; Chen, Yao; Shi, Gao-Lian; Wu, Shao-Hua

2014-01-01

Highlights: • A novel high temperature self-lubricating wear-resistant coating was fabricated. • TiC carbides and self-lubricant CaF 2 were “in situ” synthesized in the coating. • The coating with the addition of CaF 2 possessed superior properties than without. - Abstract: To improve the high-temperature tribological properties of Ti–6Al–4V alloy, γ-NiCrAlTi/TiC and γ-NiCrAlTi/TiC/CaF 2 coatings were fabricated on Ti–6Al–4V alloy by laser cladding. The phase compositions and microstructure of the coatings were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The tribological behaviors were evaluated using a ball-on-disk tribometer from ambient temperature to 600 °C under dry sliding wear conditions and the corresponding wear mechanisms were discussed. The results indicated that the γ-NiCrAlTi/TiC/CaF 2 coating consisted of α-Ti, the “in situ” synthesized TiC block particles and dendrite, γ-NiCrAlTi solid solution and spherical CaF 2 particles. The wear rates of γ-NiCrAlTi/TiC/CaF 2 coating were decreased greatly owing to the combined effects of the reinforced carbides and continuous lubricating films. Furthermore, the friction coefficients of γ-NiCrAlTi/TiC/CaF 2 coating presented minimum value of 0.21 at 600 °C, which was reduced by 43% and 50% compared to the substrate and γ-NiCrAlTi/TiC coating respectively. It was considered that the γ-NiCrAlTi/TiC/CaF 2 coating exhibited excellent friction-reducing and anti-wear properties at high temperature

Proton irradiation studies on pure Ti and Ti-6Al-4V

Energy Technology Data Exchange (ETDEWEB)

Dutta Gupta, A. [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Mukherjee, P., E-mail: paramita@vecc.gov.in [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Gayathri, N.; Bhattacharyya, P.; Bhattacharya, M. [Variable Energy Cyclotron Centre, HBNI, 1/AF Bidhannagar, Kolkata (India); Sarkar, Apu [Materials Group, Bhabha Atomic Research Centre, Mumbai (India); Sen, S. [Mechanical Engineering, Jadavpur University, Kolkata (India); Mitra, M.K. [Metallurgical and Materials Engineering, Jadavpur University, Kolkata (India)

2016-11-15

Post irradiated microstructural characterisation of pure Ti and Ti-6Al-4V has been done as a function of dose using different model based techniques of X-ray diffraction line profile analysis. There is a systematic change of domain size for both the materials with dose but the microstrain within the domain remains almost unaltered. The domain size appears to be lower for pure Ti at all doses as compared to Ti-6Al-4V alloy. XRD peaks became highly asymmetric particularly at a dose of 5 × 10{sup 21} p/m{sup 2} for Ti-6Al-4V samples which is not observed for pure Ti at the same dose. This may be attributed to the segregation of alloying elements as a result of irradiation. Microhardness values increases with dose for pure Ti and then saturates at higher doses whereas microhardness values are found to decrease at higher doses for Ti-6Al-4V.

Wear characteristics of TiO[sub 2] coating and silicon carbide alloyed layer on Ti-6Al-4V material

Energy Technology Data Exchange (ETDEWEB)

Karamis, M.B. (Dept. of Mechanical Engineering, Erciyes Univ., Kayseri (Turkey))

1992-08-14

Wear properties of Ti-6Al-4V material (IMI-318) TiO[sub 2] coated and electron beam alloyed with silicon carbide were tested. Thickness of oxide coating, alloying conditions and properties of the alloyed layer such as hardness, layer thickness and microstructure are described. Wear tests were carried out on a general-purpose wear machine by using a disc-disc sample configuration under lubricated conditions. Counterface materials to oxide-coated and to surface-alloyed specimens were plasma-nitrided AISI 51100 and hardened AISI 4140 respectively. The resulting weight loss and wear resistance were monitored as a function of sliding distance and applied load. Although the electron beam alloying improved the wear resistance of Ti-6Al-4V material, the oxide coatings on the material were not resistant to wear. (orig.).

Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

Science.gov (United States)

Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

2017-10-01

TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

Performance of V-Cr-Ti alloys in a hydrogen environment

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W. K.

2000-01-01

A systematic study is underway at Argonne National Laboratory to evaluate the mechanical properties of several V-Cr-Ti alloys after exposure to environments containing hydrogen at various partial pressures. The goal is to correlate the chemistry of the exposure environment with hydrogen uptake by the samples and with the resulting influence on microstructures and tensile properties of the alloys. Other variables examined are specimen cooling rate and synergistic effects, if any, of oxygen and hydrogen on tensile behavior of the alloys. Experiments were conducted to evaluate the effect of pH 2 in the range of 3 x 10 -6 and 1 torr on tensile properties of two V-Cr-Ti alloys. Up to pH 2 of 0.05 torr, negligible effect of H was observed on either maximum engineering stress or uniform and total elongation. However, uniform and total elongation decreased substantially when the alloys were exposed at 500 C to 1.0 torr of H 2 pressure. Preliminary data from sequential exposures of the materials to low-pO 2 and several low-pH 2 environments did not reveal adverse effects on the maximum engineering stress or on uniform and total elongation when the alloy contained ∼ 2,000 wppm O and 16 wppm H. Furthermore, tests in H 2 -exposed specimens, initially annealed at various temperatures, showed that grain-size variation by a factor of ∼ 2 had little or no effect on tensile properties. Also, specimen cooling rate had a small effect, if any, on the tensile properties of the alloy

Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

Energy Technology Data Exchange (ETDEWEB)

Wang, Z.X.; Wu, H.R.; Shan, X.L.; Lin, N.M.; He, Z.Y., E-mail: tyuthzy@126.com; Liu, X.P.

2016-12-01

Graphical abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of Ni modified layer was measured by nano indenter. The results showed that Ni modified layers exhibited triple layers structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni{sub 3}Ti, NiTi, Ti{sub 2}Ni, AlNi{sub 3} and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surface of the untreated and treated Ti6Al4V sample using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different value, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of Ni modified layer was also discussed. - Highlights: • The Ni modified layers were prepared by the plasma surface alloying technique. • Triple layers structure was prepared. • Using Micro-slurry-jet Erosion method. • The erosion rate of Ni modified layer experienced the process of descending first and then ascending. • Improvement of erosion resistance performance of Ni-rich alloying layer was prominent. The wear mechanism of Ni modified layer showed micro-cutting wearing. - Abstract: The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition

Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

Directory of Open Access Journals (Sweden)

Xinge Zhang

2017-10-01

Full Text Available Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness, and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase.

Microstructural examination of V-(4-5%) Cr-(4-5%)Ti irradiated in X530

Energy Technology Data Exchange (ETDEWEB)

Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Chung, H.M. [Argonne Natinonal Lab., IL (United States)

1997-08-01

Microstructural examination results are reported for two heats of V-(4-5%)Cr-(4-5%)Ti irradiated in the X530 experiment to {approximately}400{degrees}C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to be affected by preirradiation heat treatment at 950-1125{degrees}C. There was no evidence for a significant density of large (diameter >10 nm) dislocation loops or network dislocations.

Investigation of laser cladding high temperature anti-wear composite coatings on Ti6Al4V alloy with the addition of self-lubricant CaF{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Xiang, Zhan-Feng [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Liu, Xiu-Bo, E-mail: liuxiubo@suda.edu.cn [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Ren, Jia; Luo, Jian; Shi, Shi-Hong; Chen, Yao [School of Mechanical and Electric Engineering, Soochow University, 178 East Ganjiang Road, Suzhou 215006 (China); Shi, Gao-Lian; Wu, Shao-Hua [Suzhou Institute of Industrial Technology, Suzhou 215104 (China)

2014-09-15

Highlights: • A novel high temperature self-lubricating wear-resistant coating was fabricated. • TiC carbides and self-lubricant CaF{sub 2} were “in situ” synthesized in the coating. • The coating with the addition of CaF{sub 2} possessed superior properties than without. - Abstract: To improve the high-temperature tribological properties of Ti–6Al–4V alloy, γ-NiCrAlTi/TiC and γ-NiCrAlTi/TiC/CaF{sub 2} coatings were fabricated on Ti–6Al–4V alloy by laser cladding. The phase compositions and microstructure of the coatings were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The tribological behaviors were evaluated using a ball-on-disk tribometer from ambient temperature to 600 °C under dry sliding wear conditions and the corresponding wear mechanisms were discussed. The results indicated that the γ-NiCrAlTi/TiC/CaF{sub 2} coating consisted of α-Ti, the “in situ” synthesized TiC block particles and dendrite, γ-NiCrAlTi solid solution and spherical CaF{sub 2} particles. The wear rates of γ-NiCrAlTi/TiC/CaF{sub 2} coating were decreased greatly owing to the combined effects of the reinforced carbides and continuous lubricating films. Furthermore, the friction coefficients of γ-NiCrAlTi/TiC/CaF{sub 2} coating presented minimum value of 0.21 at 600 °C, which was reduced by 43% and 50% compared to the substrate and γ-NiCrAlTi/TiC coating respectively. It was considered that the γ-NiCrAlTi/TiC/CaF{sub 2} coating exhibited excellent friction-reducing and anti-wear properties at high temperature.

Search for high entropy alloys in the X-NbTaTiZr systems (X = Al, Cr, V, Sn)

Energy Technology Data Exchange (ETDEWEB)

Poletti, Marco Gabriele, E-mail: marcogabriele.poletti@unito.it [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy); Fiore, Gianluca [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy); Szost, Blanka A. [Strategic and Emerging Technologies Team (TEC-TS), European Space Agency, ESTEC, 1 Keplerlaan, 2201 AZ Noordwijk (Netherlands); Battezzati, Livio [Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino (Italy)

2015-01-25

Highlights: • Composition of refractory high entropy alloys predicted. • Solid solutions found in VNbTaTiZr and AlNbTaTiZr. • Alloys containing Cr and Sn are multi-phased. - Abstract: High entropy alloys, i.e. solid solution phases, are sought in the X-NbTaTiZr equiatomic system where the X element was chosen as Al, Cr, V and Sn by applying recent criteria based on size and electronegativity mismatch of alloy components, number of itinerant and total valence electrons, and the temperature at which the free energy of mixing changes at the alloy composition. The alloys containing V and Al are mostly constituted by solid solutions in good agreement with prediction.

Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600-700 C

Energy Technology Data Exchange (ETDEWEB)

Lin, Qiaoli; Li, Fuxiang; Jin, Peng; Yu, Weiyuan [Lanzhou Univ. of Technology (China). State Key Lab. of Advanced Processing and Recycling of Non-ferrous Metal

2017-06-15

Wetting of Ti-6Al-4V alloy by two industrial grade Al alloys (i.e., Al 6061 and 4043 alloys) was studied using the sessile drop method at 600-700 C under high vacuum. Al/Ti-6Al-4V is a typical reactive wetting system with good final wettability accompanied by the formation of precursor film which is actually an extended reaction layer. The formation mechanism for the precursor film is ''subcutaneous infiltration''. The small amount of alloying element Si in the alloys can cause significant segregation at the liquid/solid interface which satisfies the thermodynamic condition. The wetting behavior can be described by the classic reaction product control models, and Ti{sub 7}Al{sub 5}Si{sub 12} decomposition and Al{sub 3}Ti formation correspond to the two spreading stages. The small difference in alloying elements in Al 6061 and 4043 resulted in distinctly different interface structures, formation of precursor film and spreading dynamics, especially for the Si segregation at the interface.

A study on wear resistance and microcrack of the Ti3Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Li Jianing; Chen Chuanzhong; Squartini, Tiziano; He Qingshan

2010-01-01

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti 3 Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti 3 Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti 3 Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti 3 Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Corrosion Behavior of Ti-13Nb-13Zr and Ti-6Al-4V Alloys for Biomaterial Application

Energy Technology Data Exchange (ETDEWEB)

Saji, Viswanathan S.; Jeong, Yong Hoon; Choe, Han Cheol [Chosun University, Gwangju (Korea, Republic of); Yu, Jin Woo [Shingyeong University, Hwaseong (Korea, Republic of)

2010-02-15

Ti-13Nb-13Zr (TNZ) alloy has attracted considerable research attention in the last decade as a suitable substitute for the commercially used Ti-6Al-4V (TAV) alloy for orthopedic and dental implant applications. Hence, in the present work, a comparative evaluation has been performed on the electrochemical corrosion behavior of TNZ and TAV alloys in 0.9 wt.% NaCl solution. The result of the study showed that both the alloys had similar electrochemical behavior. The corrosion resistance of TAV alloy is found to be marginally superior to that of TNZ alloy.

Corrosion Behavior of Ti-13Nb-13Zr and Ti-6Al-4V Alloys for Biomaterial Application

International Nuclear Information System (INIS)

Saji, Viswanathan S.; Jeong, Yong Hoon; Choe, Han Cheol; Yu, Jin Woo

2010-01-01

Ti-13Nb-13Zr (TNZ) alloy has attracted considerable research attention in the last decade as a suitable substitute for the commercially used Ti-6Al-4V (TAV) alloy for orthopedic and dental implant applications. Hence, in the present work, a comparative evaluation has been performed on the electrochemical corrosion behavior of TNZ and TAV alloys in 0.9 wt.% NaCl solution. The result of the study showed that both the alloys had similar electrochemical behavior. The corrosion resistance of TAV alloy is found to be marginally superior to that of TNZ alloy

Laser Powder Cladding of Ti-6Al-4V α/β Alloy

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Samar Reda Al-Sayed Ali

2017-10-01

Full Text Available Laser cladding process was performed on a commercial Ti-6Al-4V (α + β titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. Four-track deposition of a blended powder consisting of 60 wt % tungsten carbide (WC and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The laser cladding samples were subjected to thorough microstructure examinations, microhardness and abrasion tests. Phase identification was obtained by X-ray diffraction (XRD. The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J·mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times.

Qualification of Ti6Al4V ELI Alloy Produced by Laser Powder Bed Fusion for Biomedical Applications

Science.gov (United States)

Yadroitsev, I.; Krakhmalev, P.; Yadroitsava, I.; Du Plessis, A.

2018-03-01

Rectangular Ti6Al4V extralow interstitials (ELI) samples were manufactured by laser powder bed fusion (LPBF) in vertical and horizontal orientations relative to the build platform and subjected to various heat treatments. Detailed analyses of porosity, microstructure, residual stress, tensile properties, fatigue, and fracture surfaces were performed based on x-ray micro-computed tomography, scanning electron microscopy, and x-ray diffraction methods. The types of fracture and the tensile fracture mechanisms of the LPBF Ti6Al4V ELI alloy were also studied. Detailed analysis of the microstructure and the corresponding mechanical properties were compared against standard specifications for conventional Ti6Al4V alloy for use in surgical implant applications. Conclusions regarding the mechanical properties and heat treatment of LPBF Ti6Al4V ELI for biomedical applications are made.

Cyclic hydrogenation stability of γ-hydrides for Ti{sub 25}V{sub 35}Cr{sub 40} alloys doped with carbon

Energy Technology Data Exchange (ETDEWEB)

Shen, Chia-Chieh, E-mail: ccshen@saturn.yzu.edu.tw [Department of Mechanical Engineering, Yuan Ze University, Chungli 32003, Taiwan (China); Graduate School of Renewable Energy and Engineering, Yuan Ze University, Chungli 32003, Taiwan (China); Fuel Cell Center, Yuan Ze University, Chungli 32003, Taiwan (China); Li, Hsueh-Chih [Graduate School of Renewable Energy and Engineering, Yuan Ze University, Chungli 32003, Taiwan (China)

2015-11-05

An automatic Sievert's apparatus equipped with a temperature-programmed desorption spectrometer was constructed to study the stability of annealed Ti{sub 25}V{sub 35}Cr{sub 40}C{sub x} (x = 0 and 0.1) alloy under cyclic hydrogenation at 6 N H{sub 2}. The specimens were tested at 30 °C with a hydrogen loading of around 1.00 H/M, which enabled the phase transformation from β-to γ-hydrides. After 500 cycles, 83% and 90% of the initial hydrogen capacities were preserved for Ti{sub 25}V{sub 35}Cr{sub 40} and Ti{sub 25}V{sub 35}Cr{sub 40}C{sub 0.1}, respectively. Therefore, a small amount of C doping was effective in reducing the hydrogenation degradation of Ti{sub 25}V{sub 35}Cr{sub 40}. The hydrogenation degradation of Ti{sub 25}V{sub 35}Cr{sub 40} was examined by measuring the P–C isotherms, temperature-programmed desorption spectra, and X-ray diffraction patterns. The degradation was ascribed to intrinsic disproportionation, i.e., Ti{sub 0.25}V{sub 0.35}Cr{sub 0.40} + 0.88H{sub 2} → yTiH{sub 2} + Ti{sub 0.25−y}V{sub 0.35}Cr{sub 0.40}H{sub 1.76–2y}, where the coefficient y indicates the amount of Ti-rich precipitate. The better cyclic hydrogenation stability of Ti{sub 25}V{sub 35}Cr{sub 40}C{sub 0.1} was related to the suppression of intrinsic disproportionation by the presence of carbon atoms in the body-centered-cubic lattice. - Highlights: • The stability of γ-hydride for Ti{sub 25}V{sub 35}Cr{sub 40} alloys was examined for 500 cycles. • The γ-hydride of Ti{sub 25}V{sub 35}Cr{sub 40} alloy degraded by intrinsic disproportionation. • The disproportionation of γ-hydride can be suppressed through carbon inclusion.

Structure and grindability of dental Ti-Cr alloys

International Nuclear Information System (INIS)

Hsu, H.-C.; Wu, S.-C.; Chiang, T.-Y.; Ho, W.-F.

2009-01-01

The purpose of this study was to investigate the structure and microhardness of a series of binary Ti-Cr alloys with Cr contents up to 30 wt%. In addition, the grindability was also evaluated using an electric dental handpiece with SiC wheels, with the goal of developing a titanium alloy with better mechanical properties and machinability than commercially pure titanium (c.p. Ti), a metal generally considered to be difficult to machine. This study evaluated the phase and structure of Ti-Cr alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. Grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min. Results indicated that the structure of Ti-Cr alloys is sensitive to the Cr content. The cast c.p. Ti has a hexagonal α phase. With 5 wt% Cr, metastable β phase starts to be retained. With Cr contents higher than 10 wt%, the equi-axed β phase is almost entirely retained. In addition, athermal ω phase was found in the Ti-5Cr and Ti-10Cr alloys. The largest quantity of ω phase and highest microhardness were found in Ti-10Cr alloy. The grinding rate of the Ti-Cr alloys showed a similar tendency to the microhardness. The Ti-10Cr alloy exhibited the best grindability, especially at 1000 m/min, which presumably due to the brittle nature of the alloy containing the ω phase in the β matrix.

Effect of phase transformations on laser forming of Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Fan, Y.; Cheng, P.; Yao, Y.L.; Yang, Z.; Egland, K.

2005-01-01

In laser forming, phase transformations in the heat-affected zone take place under steep thermal cycles, and have a significant effect on the flow behavior of Ti-6Al-4V alloy and the laser-forming process. The flow-stress data of a material are generally provided as only dependent on strain, strain rate, and temperature, while phase transformations are determined by both temperature and temperature history. Therefore, effect of phase transformations on the flow behavior of materials in thermomechanical processing is not given necessary considerations. In the present work, both the α→β transformation during heating and the decomposition of β phase, producing martensite α ' or lamellae α dependent on cooling rate, are numerically investigated. The spatial distribution of volume fractions of phases is obtained by coupling thermal and phase transformation kinetic modeling. Consequently, the flow stress of Ti-6Al-4V alloy is calculated by the rule of mixtures based on the phase ratio and the flow stress of each single phase, which is also a function of temperature, strain, and strain rate. According to the obtained flow-stress data, the laser-forming process of Ti-6Al-4V alloy is modeled by finite element method, and the deformation is predicted. A series of carefully controlled experiments are conducted to validate the theoretically predicted results

Wear behaviour of nitrogen-implanted and nitrided Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Martinella, R.; Giovanardi, S.; Chevallard, G.; Villani, M.; Molinari, A.; Tosello, C.

1985-01-01

The comparison between the wear behaviour of nitrogen-implanted Ti-6Al-4V alloy and that of nitrided Ti-6Al-4V alloy is reported. Both treatments were carried out at temperatures from 573 to 973 K on lapped surfaces; in order to compare roughness effects, nitriding was also carried out on rougher samples. An improvement in wear resistance for lapped surfaces was noted after implantation at 573 K or higher temperatures and after nitriding at temperatures over 773 K only; however, at 873 K, nitriding was more effective than implantation. Rough nitrided surfaces showed better wear resistance than lapped nitrided surfaces or lapped implanted surfaces. Most probably the improvement in wear resistance on implanted samples is due to a reduction in friction induced by chemical modification of the surface as a result of oxide and TiN. Scanning electron microscopy observations which show subsurface voids and coalescence are in good agreement with a wear model previously reported. As implantation preserves the surface finish, a possible application is suggested. (Auth.)

Oxidation and microstrucure of V-Cr-Ti alloys exposed to oxygen-containing environments

Energy Technology Data Exchange (ETDEWEB)

Natesan, K. [Argonne National Lab., IL (United States); Uz, M. [Lafayette College, Easton, PA (United States); Ulie, T.

1997-08-01

The objectives of this task are to (a) evaluate the oxygen uptake of several V-Cr-Ti alloys as a function of temperature and oxygen partial pressure in the exposure environment, (b) examine the microstructural characteristics of oxide scales and oxygen trapped at the grain boundaries in the substrate alloys, and (c) evaluate the influence of alloy composition on oxygen uptake and develop correlation(s) between alloy composition, exposure environment, and temperature.

Oxidation and microstrucure of V-Cr-Ti alloys exposed to oxygen-containing environments

International Nuclear Information System (INIS)

Natesan, K.; Uz, M.; Ulie, T.

1997-01-01

The objectives of this task are to (a) evaluate the oxygen uptake of several V-Cr-Ti alloys as a function of temperature and oxygen partial pressure in the exposure environment, (b) examine the microstructural characteristics of oxide scales and oxygen trapped at the grain boundaries in the substrate alloys, and (c) evaluate the influence of alloy composition on oxygen uptake and develop correlation(s) between alloy composition, exposure environment, and temperature

Evaluation of Surface Mechanical Properties and Grindability of Binary Ti Alloys Containing 5 wt % Al, Cr, Sn, and V

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Hae-Soon Lim

2017-11-01

Full Text Available This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti. Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05.

Comparison on mechanical anisotropies of selective laser melted Ti-6Al-4V alloy and 304 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Yu, Hanchen; Yang, Jingjing; Yin, Jie; Wang, Zemin, E-mail: zmwang@hust.edu.cn; Zeng, Xiaoyan

2017-05-17

Near-fully dense Ti-6Al-4V and 304 stainless steel samples have been produced applying selective laser melting (SLM) in the present work. The microstructures, textures and microhardnesses on horizontal and vertical cross sections, as well as the tensile properties of horizontally and vertically SLMed samples are investigated. It is found that the microstructures of the two SLMed alloys are mainly composed of hexagonal close-packed (HCP) martensitic phase or face-centered cubic (FCC) austenitic phase within columnar structures in Ti-6Al-4V alloy and 304 stainless steel, respectively. For both SLMed alloys, the tensile properties and microhardnesses show anisotropic though the textures are weak. Especially, the Ti-6Al-4V samples show even stronger anisotropic mechanical properties compared with 304 stainless steel. The higher length-width ratios of the columnar structures, rather than the weaker textures or the less symmetry of HCP crystal structure in SLMed Ti-6Al-4V are believed to be responsible for the stronger mechanical anisotropies. As expected, heat treatment is an effective method to eliminate columnar structures and leads to nearly isotropic mechanical properties.

High-pressure coolant effect on the surface integrity of machining titanium alloy Ti-6Al-4V: a review

Science.gov (United States)

Liu, Wentao; Liu, Zhanqiang

2018-03-01

Machinability improvement of titanium alloy Ti-6Al-4V is a challenging work in academic and industrial applications owing to its low thermal conductivity, low elasticity modulus and high chemical affinity at high temperatures. Surface integrity of titanium alloys Ti-6Al-4V is prominent in estimating the quality of machined components. The surface topography (surface defects and surface roughness) and the residual stress induced by machining Ti-6Al-4V occupy pivotal roles for the sustainability of Ti-6Al-4V components. High-pressure coolant (HPC) is a potential choice in meeting the requirements for the manufacture and application of Ti-6Al-4V. This paper reviews the progress towards the improvements of Ti-6Al4V surface integrity under HPC. Various researches of surface integrity characteristics have been reported. In particularly, surface roughness, surface defects, residual stress as well as work hardening are investigated in order to evaluate the machined surface qualities. Several coolant parameters (including coolant type, coolant pressure and the injection position) deserve investigating to provide the guidance for a satisfied machined surface. The review also provides a clear roadmap for applications of HPC in machining Ti-6Al4V. Experimental studies and analysis are reviewed to better understand the surface integrity under HPC machining process. A distinct discussion has been presented regarding the limitations and highlights of the prospective for machining Ti-6Al4V under HPC.

In vitro biocorrosion of Ti-6Al-4V implant alloy by a mouse macrophage cell line.

Science.gov (United States)

Lin, Hsin-Yi; Bumgardner, Joel D

2004-03-15

Corrosion of implant alloys releasing metal ions has the potential to cause adverse tissue reactions and implant failure. We hypothesized that macrophage cells and their released reactive chemical species (RCS) affect the alloy's corrosion properties. A custom cell culture corrosion box was used to evaluate how cell culture medium, macrophage cells and RCS altered the Ti-6Al-4V corrosion behaviors in 72 h and how corrosion products affected the cells. There was no difference in the charge transfer in the presence (75.2 +/- 17.7 mC) and absence (62.3 +/- 18.8 mC) of cells. The alloy had the lowest charge transfer (28.2 +/- 4.1 mC) and metal ion release (Ti < 10 ppb, V < 2 ppb) with activated cells (releasing RCS) compared with the other two conditions. This was attributed to an enhancement of the surface oxides by RCS. Metal ion release was very low (Ti < 20 ppb, V < 10 ppb) with nonactivated cells and did not change cell morphology, viability, and NO and ATP release compared with controls. However, IL-1beta released from the activated cells and the proliferation of nonactivated cells were greater on the alloy than the controls. In summary, macrophage cells and RCS reduced the corrosion of Ti-6Al-4V alloys as hypothesized. These data are important in understanding host tissue-material interactions. Copyright 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 717-724, 2004

Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

Science.gov (United States)

Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

2017-12-01

Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

A study on wear resistance and microcrack of the Ti{sub 3}Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

Energy Technology Data Exchange (ETDEWEB)

Li Jianing, E-mail: ljnljn1022@163.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Chen Chuanzhong [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Squartini, Tiziano [INFM-Department of Physics, Siena University, Siena 53100 (Italy); He Qingshan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China)

2010-12-15

Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti{sub 3}Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti{sub 3}Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti{sub 3}Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti{sub 3}Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

Science.gov (United States)

Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

2017-08-08

The TiC p /Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiC p /Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiC p -reinforced Cu-Cr-Zr composites. Results show that nano-sized TiC p can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiC p . The grain size decreased from 82 to 28 μm with the nano-sized TiC p content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σ UCS ) and yield strength (σ 0.2 ) of 4 wt% TiC p -reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiC p -reinforced Cu-Cr-Zr composites decreased with the increasing TiC p content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

Revised ANL-reported tensile data for unirradiated and irradiated (FFTF, HFIR) V-Ti and V-Cr-Ti alloys

International Nuclear Information System (INIS)

Billone, M.C.

1998-01-01

The tensile data for all unirradiated and irradiated vanadium alloys samples tested at Argonne National Laboratory (ANL) have been critically reviewed and, when necessary, revised. The review and revision are based on reanalyzing the original load-displacement strip chart recordings by a methodology consistent with current ASTM standards. For unirradiated alloys (162 samples), the revised values differ from the previous values as follows: -11±19 MPa (-4±6%) for yield strength (YS), -3±15 MPa (-1±3%) for ultimate tensile strength (UTS), -5±2% strain for uniform elongation (UE), and -4±2% strain for total elongation (TE). Of these changes, the decrease in -1±6 MPa (0±1%) for UTS, -5±2% for UE, and -4±2% for TE. Of these changes, the decrease in UE values for alloys irradiated and tested at 400--435 C is the most significant. This decrease results from the proper subtraction of nongauge-length deformation from measured crosshead deformation. In previous analysis of the tensile curves, the nongauge-length deformation was not correctly determined and subtracted from the crosshead displacement. The previously reported and revised tensile values for unirradiated alloys (20--700 C) are tabulated in Appendix A. The revised tensile values for the FFTF-irradiated (400--600 C) and HFIR-irradiated (400 C) alloys are tabulated in Appendix B, along with the neutron damage and helium levels. Appendix C compares the revised values to the previously reported values for irradiated alloys. Appendix D contains previous and revised values for the tensile properties of unirradiated V-5Cr-5Ti (BL-63) alloy exposed to oxygen

Functionalization of Biomedical Ti6Al4V via In Situ Alloying by Cu during Laser Powder Bed Fusion Manufacturing

Science.gov (United States)

Krakhmalev, Pavel; Yadroitsev, Igor; Yadroitsava, Ina; de Smidt, Olga

2017-01-01

The modern medical industry successfully utilizes Laser Powder Bed Fusion (LPBF) to manufacture complex custom implants. Ti6Al4V is one of the most commonly used biocompatible alloys. In surgery practice, infection at the bone–implant interface is one of the key reasons for implant failure. Therefore, advanced implants with biocompatibility and antibacterial properties are required. Modification of Ti alloy with Cu, which in small concentrations is a proven non-toxic antibacterial agent, is an attractive way to manufacture implants with embedded antibacterial functionality. The possibility of achieving alloying in situ, during manufacturing, is a unique option of the LPBF technology. It provides unique opportunities to manufacture customized implant shapes and design new alloys. Nevertheless, optimal process parameters need to be established for the in situ alloyed materials to form dense parts with required mechanical properties. This research is dedicated to an investigation of Ti6Al4V (ELI)-1 at % Cu material, manufactured by LPBF from a mixture of Ti6Al4V (ELI) and pure Cu powders. The effect of process parameters on surface roughness, chemical composition and distribution of Cu was investigated. Chemical homogeneity was discussed in relation to differences in the viscosity and density of molten Cu and Ti6Al4V. Microstructure, mechanical properties, and fracture behavior of as-built 3D samples were analyzed and discussed. Pilot antibacterial functionalization testing of Ti6Al4V (ELI) in situ alloyed with 1 at % Cu showed promising results and notable reduction in the growth of pure cultures of Escherichia coli and Staphylococcus aureus. PMID:28972546

Functionalization of Biomedical Ti6Al4V via In Situ Alloying by Cu during Laser Powder Bed Fusion Manufacturing

Directory of Open Access Journals (Sweden)

Pavel Krakhmalev

2017-10-01

Full Text Available The modern medical industry successfully utilizes Laser Powder Bed Fusion (LPBF to manufacture complex custom implants. Ti6Al4V is one of the most commonly used biocompatible alloys. In surgery practice, infection at the bone–implant interface is one of the key reasons for implant failure. Therefore, advanced implants with biocompatibility and antibacterial properties are required. Modification of Ti alloy with Cu, which in small concentrations is a proven non-toxic antibacterial agent, is an attractive way to manufacture implants with embedded antibacterial functionality. The possibility of achieving alloying in situ, during manufacturing, is a unique option of the LPBF technology. It provides unique opportunities to manufacture customized implant shapes and design new alloys. Nevertheless, optimal process parameters need to be established for the in situ alloyed materials to form dense parts with required mechanical properties. This research is dedicated to an investigation of Ti6Al4V (ELI-1 at % Cu material, manufactured by LPBF from a mixture of Ti6Al4V (ELI and pure Cu powders. The effect of process parameters on surface roughness, chemical composition and distribution of Cu was investigated. Chemical homogeneity was discussed in relation to differences in the viscosity and density of molten Cu and Ti6Al4V. Microstructure, mechanical properties, and fracture behavior of as-built 3D samples were analyzed and discussed. Pilot antibacterial functionalization testing of Ti6Al4V (ELI in situ alloyed with 1 at % Cu showed promising results and notable reduction in the growth of pure cultures of Escherichia coli and Staphylococcus aureus.

Carbon fiber reinforced magnesium alloy in a Ti-6Al-4V shell

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Astanin Vasily

2017-01-01

Full Text Available Continuous carbon fiber reinforced magnesium alloy pieces in SMC Ti-6Al-4V shell have been fabricated using pressure infiltration. Similar temperatures (~700°C for superplastic formation of the shell and melting of the alloy allow this to be done in one step. The quality of infiltration of the molten alloys is found to be proportional to load. A limiting parameter in increasing the infiltration pressure is the strength of the welded bonds. Structure, fracture parameters and mechanical properties are discussed.

Modeling of Processing-Induced Pore Morphology in an Additively-Manufactured Ti-6Al-4V Alloy.

Science.gov (United States)

Kabir, Mohammad Rizviul; Richter, Henning

2017-02-08

A selective laser melting (SLM)-based, additively-manufactured Ti-6Al-4V alloy is prone to the accumulation of undesirable defects during layer-by-layer material build-up. Defects in the form of complex-shaped pores are one of the critical issues that need to be considered during the processing of this alloy. Depending on the process parameters, pores with concave or convex boundaries may occur. To exploit the full potential of additively-manufactured Ti-6Al-4V, the interdependency between the process parameters, pore morphology, and resultant mechanical properties, needs to be understood. By incorporating morphological details into numerical models for micromechanical analyses, an in-depth understanding of how these pores interact with the Ti-6Al-4V microstructure can be gained. However, available models for pore analysis lack a realistic description of both the Ti-6Al-4V grain microstructure, and the pore geometry. To overcome this, we propose a comprehensive approach for modeling and discretizing pores with complex geometry, situated in a polycrystalline microstructure. In this approach, the polycrystalline microstructure is modeled by means of Voronoi tessellations, and the complex pore geometry is approximated by strategically combining overlapping spheres of varied sizes. The proposed approach provides an elegant way to model the microstructure of SLM-processed Ti-6Al-4V containing pores or crack-like voids, and makes it possible to investigate the relationship between process parameters, pore morphology, and resultant mechanical properties in a finite-element-based simulation framework.

Modeling of Processing-Induced Pore Morphology in an Additively-Manufactured Ti-6Al-4V Alloy

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Mohammad Rizviul Kabir

2017-02-01

Full Text Available A selective laser melting (SLM-based, additively-manufactured Ti-6Al-4V alloy is prone to the accumulation of undesirable defects during layer-by-layer material build-up. Defects in the form of complex-shaped pores are one of the critical issues that need to be considered during the processing of this alloy. Depending on the process parameters, pores with concave or convex boundaries may occur. To exploit the full potential of additively-manufactured Ti-6Al-4V, the interdependency between the process parameters, pore morphology, and resultant mechanical properties, needs to be understood. By incorporating morphological details into numerical models for micromechanical analyses, an in-depth understanding of how these pores interact with the Ti-6Al-4V microstructure can be gained. However, available models for pore analysis lack a realistic description of both the Ti-6Al-4V grain microstructure, and the pore geometry. To overcome this, we propose a comprehensive approach for modeling and discretizing pores with complex geometry, situated in a polycrystalline microstructure. In this approach, the polycrystalline microstructure is modeled by means of Voronoi tessellations, and the complex pore geometry is approximated by strategically combining overlapping spheres of varied sizes. The proposed approach provides an elegant way to model the microstructure of SLM-processed Ti-6Al-4V containing pores or crack-like voids, and makes it possible to investigate the relationship between process parameters, pore morphology, and resultant mechanical properties in a finite-element-based simulation framework.

Modification of Ti6Al4V surface by diazonium compounds

Science.gov (United States)

Sandomierski, Mariusz; Buchwald, Tomasz; Strzemiecka, Beata; Voelkel, Adam

2018-02-01

Ti6Al4V alloy is the most commonly used in orthopedic industry as an endoprosthesis. Ti6Al4V exhibits good mechanical properties, except the abrasion resistance. Surface modification of Ti6Al4V in order to obtain organic layer, and then the attachment of the polymer, can allow for overcoming this problem. The aim of the work was the modification of Ti6Al4V surface by diazonium compounds: salt or cation generated in situ and examine the influence of the reducing agent - ascorbic acid, and the temperature of reaction on modification process. Moreover, the simulated body fluid was used for the assessment of the organic layer stability on Ti6Al4V surface. The evaluation of the modification was carried out using the following methods: Raman microspectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Higher temperature of modification by 4-hydroxymethylbenzenediazonium cation, provides the largest amount of organic layer on the Ti6Al4V alloy. In the case of the Ti6Al4V modified by Variamine Blue B salt, the amount of organic layer is not dependent on the reaction condition. Moreover, the ascorbic acid and the presence of TiO2 does not effect on the modification. The modified surface is completely coated with the organic layer which is stable in simulated body fluid.

Permeation of deuterium implanted into V-15Cr-5Ti

International Nuclear Information System (INIS)

Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

1987-01-01

Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D 3 + ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4x10 -8 exp(-0.11 eV/kT)(m 2 /s), over the temperature range 723 K to 823 K. (orig.)

Permeation of deuterium implanted into V-15Cr-5Ti

Science.gov (United States)

Anderl, R. A.; Longhurst, G. R.; Struttmann, D. A.

1987-02-01

Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D 3+ ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4 × 10 -8 exp( -0.11 eV/ kT) (m 2/s), over the temperature range 723 K to 823 K.

Grinding behavior and surface appearance of (TiCp + TiBw/Ti-6Al-4V titanium matrix composites

Directory of Open Access Journals (Sweden)

Ding Wenfeng

2014-10-01

Full Text Available (TiCp + TiBw/Ti-6Al-4V titanium matrix composites (PTMCs have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.

Liquid phase surface nitriding of Ti-6Al-4V pre-placed with chromium

Energy Technology Data Exchange (ETDEWEB)

Vahedi Nemani, Alireza, E-mail: alireza_vahedi@ut.ac.ir; Sohi, M. Heydarzadeh; Amadeh, A.A.; Ghaffari, Mahya

2016-08-01

In this study, liquid phase surface nitriding of Ti-6Al-4V was carried out by pre-placing of chromium powder on the substrate and subsequent Tungsten Inert Gas (TIG) surface melting. The effect of the application of low and high heat inputs on the microstructure, microhardness and wear resistance of the treated layers were studied. Surface alloying with chromium in a nitrogen containing atmosphere resulted in the formation of hard intermetallic compounds such as TiN, Cr{sub 2}N and TiCr{sub 2}. Moreover, the presence of beta stabilizer chromium together with the application of high heat input during surface treatment resulted in the presence of beta phase at room temperature. However, applying low heat input could not prevent transformation of beta to martensite. The hardness of the layers fabricated at high and low heat inputs were respectively 1050 and 1200 HV{sub 0.3} compared to average 280 HV{sub 0.3} for the as-received material. Liquid phase surface treatment of titanium at the aforementioned conditions improved the wear resistance. The lowest weight loss belonged to the specimen with the beta phase matrix. The formation of the fairly ductile bcc-β phase hindered crack nucleation during wear. The weight loss in this condition was 7 times lower than that of the base material. - Highlights: • Liquid phase surface nitriding of Ti-6Al-4V was carried out by TIG surface melting. • Cr powder was pre-placed on the surface as the beta stabilizer alloying element. • The treated layers were characterized by OM, SEM and X-ray diffraction pattern. • Hardness of the layers increased up to 3 times higher than that of the base alloy. • Liquid phase surface alloying improved the wear resistance.

Reactive resistance welding of Ti6Al4V alloy with the use of Ni(V)/Al multilayers

Energy Technology Data Exchange (ETDEWEB)

Maj, Lukasz; Morgiel, Jerzy [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, Krakow (Poland); Mars, Krzysztof; Godlewska, Elzbieta [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Krakow (Poland)

2017-02-15

The freestanding Ni(V)/Al multilayer foil was applied as a filler material in order to join Ti6Al4V alloy with the use of reactive resistance welding (RRW) technique. Present investigations, performed with the use of transmission electron microscopy (TEM) method, allowed to show that an application of high current (I = 400 A for 2 min in vacuum conditions ∝10{sup -1} mbar) transformed the Ni(V)/Al multilayers into fine grain (<300 nm) NiAl phase. It also showed that the RRW process led to the formation of firm connection with nanoporosity limited only to the original contact plane between base material and the foil. Simultaneously, the formation of a narrow strip of crystallites of Ti{sub 3}Al intermetallic phase elongated along the joint line (average size of ∝200 nm) was observed. The base material was separated from the joint area by a layer of up to ∝2 μm thickness of nearly defect free α-Ti and β-Ti grains from a heat affected zone (HAZ). The performed experiment proved that Ni(V)/Al multilayer could serve as a filler material for joining of Ti6Al4V alloys even without additional solder layer. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Development and characterization of laser clad high temperature self-lubricating wear resistant composite coatings on Ti–6Al–4V alloy

International Nuclear Information System (INIS)

Liu, Xiu-Bo; Meng, Xiang-Jun; Liu, Hai-Qing; Shi, Gao-Lian; Wu, Shao-Hua; Sun, Cheng-Feng; Wang, Ming-Di; Qi, Long-Hao

2014-01-01

Highlights: • A novel high temperature self-lubricating anti-wear composite coating was fabricated. • Reinforced carbides as well as self-lubricating sulfides were in situ synthesized. • Microhardness of the Ti–6Al–4V substrate was significantly improved. • Friction coefficient and wear rate of the composite coating were greatly reduced. - Abstract: To enhance the wear resistance and friction-reducing capability of titanium alloy, a process of laser cladding γ-NiCrAlTi/TiC + TiWC 2 /CrS + Ti 2 CS coatings on Ti–6Al–4V alloy substrate with preplaced NiCr/Cr 3 C 2 –WS 2 mixed powders was studied. A novel coating without cracks and few pores was obtained in a proper laser processing. The composition and microstructure of the fabricated coating were examined by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) techniques, and tribological properties were evaluated using a ball-on-disc tribometer under dry sliding wear test conditions at 20 °C (room-temperature), 300 °C, 600 °C, respectively. The results show that the coating has unique microstructure consisting of α-Ti, TiC, TiWC 2 , γ-NiCrAlTi, Ti 2 CS and CrS phases. Average microhardness of the composite coating is 1005 HV 0.2 , which is about 3-factor higher than that of Ti–6Al–4V substrate (360 HV 0.2 ). The friction coefficient and wear rate of the coating are greatly decreased due to the combined effects of the dominating anti-wear capabilities of reinforced TiC and TiWC 2 carbides and the CrS and Ti 2 CS sulfides which have excellent self-lubricating property

Crack growth behavior of low-alloy bainitic 51CrV4 steel

OpenAIRE

Canadinç, Demircan; Lambers, H. G.; Gorny B.; Tschumak, S.; Maier, H.J.

2010-01-01

The crack growth behavior of low-alloy bainitic 51CrV4 steel was investigated. The current results indicate that the stress state present during the isothermal bainitic transformation has a strong influence on the crack propagation behavior in the near threshold regime, when the crack growth direction is perpendicular to the loading axis of the original sample undergoing phase transformation. However, the influence of stresses superimposed during the bainitic transformation on the crack growt...

Influence of cobalt and chromium additions on the precipitation processes in a Cu-4Ti alloys; Influencia de la adicion de cobalto y cromo en el proceso de precipitacion en una aleacion de Cu-4Ti

Energy Technology Data Exchange (ETDEWEB)

Donoso, E.

2010-07-01

The influence of 0.5% atomic cobalt and 1% atomic chromium additions on the precipitation hardening of Cu-4Ti alloy was studied by differential scanning calorimetry (DSC) and microhardness measurements. The analysis of the calorimetric curves, for binary alloy, shows the presence of two overlapping exothermic reactions (stages 1 and 2) attributed to the formation of Cu{sub 4}Ti and Cu{sub 3}Ti particles in the copper matrix, respectively. DSC curves for Cu-4Ti-0.5Co alloy shows three exothermic effects (overlapping stages 3 and 4 and stage 5) associated to the formation of phases Ti{sub 2}Co, TiCo and Cu{sub 4}Ti, respectively. DSC curves for Cu-4Ti1Cr alloy shows three exothermic reactions (stages 6, 7 and 9) and one endothermic peak (stage 8). The exothermic reactions correspond to the formation of phases Cr{sub 2}Ti, Cu{sub 4}Ti and Cu{sub 3}Ti, respectively, and the endothermic reactions are attributed to the Cr{sub 2}Ti dissolution. The activation energies calculated using the modified Kissinger method were lower than the ones corresponding to diffusion of cobalt, chromium, and titanium in copper. Kinetic parameters were obtained by a convolution method based on the Johnson-Mehl-Avrami (JMA) formalism. Microhardness measurements confirmed the formation of the mentioned phases. Also, these measurements confirmed the effect of cobalt and chromium addition on the binary alloy hardness. (Author). 31 refs.

Hydrogen storage study on Ti2CrV and ZrFe1.8V0.2 composite system

International Nuclear Information System (INIS)

Banerjee, S.; Kumar, A.; Pillai, C.G.S.; Sudarsan, V.

2012-01-01

Ti 2 CrV is reported to have one of the highest hydrogen storage capacities (more than 4 wt. %) among the bcc phase transition metal alloys. It has been found from the earlier study that Ti 2 CrV alloy shows quite good hydrogen absorption property but the desorption temperature is on the higher side. The in-situ temperature programmed desorption profile shows that the hydrogen desorption starts from 120℃ and the desorption peak comes at 180℃, which is slightly high for the vehicular application. On the other hand ZrFe 1.8 V 0.2 Laves phase alloy has low hydrogen absorption capacity, but at the room temperature it can desorp all its hydrogen. The pressure composition isotherm of ZrFe 1.8 V 0.2 alloy generated during the experiment shows the typical characteristics of the room temperature reversible hydride. The in-situ temperature programmed desorption shows that the hydride can desorb all the hydrogen below room temperature

Permeation of deuterium implanted into V-15Cr-5Ti

Energy Technology Data Exchange (ETDEWEB)

Anderl, R.A.; Longhurst, G.R.; Struttmann, D.A.

1987-02-01

Permeation and reemission of deuterium for the vanadium alloy, V-15Cr-5Ti, was investigated using 3 keV, D/sub 3//sup +/ ion beams from a small accelerator. The experiments consisted of measurement of the deuterium reemission and permeation rates as a function of implantation fluence for 0.5 mm thick specimens heated to temperatures from 623 K to 823 K. Implantation-side surface characterization was made by simultaneous measurements of sputtered ions with a secondary ion mass spectrometer (SIMS). For the experimental conditions used, the steady-state deuterium permeation flux in V-15Cr-5Ti is approximately 18% of the implantation flux. This is approximately 1000 times that seen in the austenitic stainless steel, PCA, and 200 times that seen in the ferritic steel, HT-9, under comparable conditions. Measurement of deuterium diffusivity in V-15Cr-5Ti using permeation break-through times indicates that D = 1.4x10/sup -8/ exp(-0.11 eVkT)(m/sup 2/s), over the temperature range 723 K to 823 K.

Feasibility study of the production of biomedical Ti-6Al-4V alloy by powder metallurgy.

Science.gov (United States)

Bolzoni, L; Ruiz-Navas, E M; Gordo, E

2015-04-01

Titanium and its alloys are characterized by an exceptional combination of properties like high strength, good corrosion resistance and biocompatibility which makes them suitable materials for biomedical prosthesis and devices. The wrought Ti-6Al-4V alloy is generally favored in comparison to other metallic biomaterials due to its relatively low elastic modulus and it has been long used to obtain products for biomedical applications. In this work an alternative route to fabricate biomedical implants made out of the Ti-6Al-4V alloy is investigated. Specifically, the feasibility of the conventional powder metallurgy route of cold uniaxial pressing and sintering is addressed by considering two types of powders (i.e. blended elemental and prealloyed). The characterization of physical properties, chemical analysis, mechanical behavior and microstructural analysis is carried out in-depth and the properties are correlated among them. On the base of the results found, the produced alloys are promising materials for biomedical applications as well as cheaper surgical devices and tools. Copyright © 2015 Elsevier B.V. All rights reserved.

An investigation of dynamic mechanical behaviour of Ti6Al4V titanium alloy at room temperature

Directory of Open Access Journals (Sweden)

Ran Chun

2016-01-01

Full Text Available To study the high strain rate shear behaviour of Ti6Al4V titanium alloy, a series of dynamic compression experiments has been performed by split Hopkinson pressure bar (SHPB using Flat Hat-shaped specimen at room temperature. Macro true shear stress-true strain curves were obtained under different strain rate loading conditions at room temperature. The effects of strain hardening and strain rate hardening on the dynamic mechanical properties of Ti6Al4V titanium alloy were discussed. Results indicate that a The higher the strain rate, the higher the flow stress, therefore, the material has obvious strain rate hardening effect, b It is ductile failure for Ti6Al4V titanium alloy under quasi-static loading condition, c For dynamical tests, the values for true shear stress increase with increasing true strain till the maximum true shear stress, on the contrary, the values for true shear stress decrease with increasing the true strain after the maximum true shear stress and d The flow stress increases with increasing the true strain under quasi-static loading condition during the plastic deformation.

Production of hard hydrophilic Ni-B coatings on hydrophobic Ni-Ti and Ti-6Al-4V alloys by electroless deposition

Energy Technology Data Exchange (ETDEWEB)

Buelbuel, Ferhat; Karabudak, Filiz; Yesildal, Ruhi [Ataturk Univ., Erzurum (Turkey). Mechanical Engineering Dept.

2017-07-01

This paper is mainly focused on the wetting state of liquid droplets on Ni-Ti and Ti-6Al-4V hierarchical structured hydrophobic surfaces in micro/nanoscale. Electroless Ni-B deposition as a surface coating treatment has recently drawn considerable attention of researchers owing to remarkable advantages when compared with other techniques such as low price, conformal ability to coat substrates, good bath stability and relatively easier plating process control. The Ni-Ti and Ti-6Al-4V substrates were plated by electroless Ni-B plating process. The coated films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness testing and static contact angle measurement. Results obtained from the analyses show that electroless Ni-B deposition may improve the hardness and wettability of the Ni-Ti and Ti-6Al-4V alloy surfaces.

Hydrogen storage performance of Ti-V-based BCC phase alloys with various Fe content

International Nuclear Information System (INIS)

Yu, X.B.; Feng, S.L.; Wu, Z.; Xia, B.J.; Xu, N.X.

2005-01-01

The effect of Fe content on hydrogen storage characteristics of Ti-10Cr-18Mn-(32-x)V-xFe (x = 0, 2, 3, 4, 5) alloys has been investigated at 353 K. The X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images of the alloys present BCC and C14 two-phase structures for all of the Fe-containing alloys. With the increasing Fe content, the lattice parameters of the BCC phase decrease, which results in an increase of the hydrogen desorption plateau pressure of the alloys. Among the studied alloys, Ti-10Cr-18Mn-27V-5Fe alloy exhibits the smallest PCT plateau slope and a more suitable plateau pressure (0.1 MPa equ <1 MPa). The maximum and effective capacities of the alloy are 3.32 wt.% and 2.26 wt.%, respectively, which are higher than other reported Fe-containing BCC phase alloys. In addition, the V/Fe ratio in this alloy is close to that of (VFe) alloy, whose cost is much lower than that of pure V

Formation of ω-phase in Zr-4 at.% Cr alloy

International Nuclear Information System (INIS)

Dobromyslov, A.V.; Kazantseva, N.V.

1996-01-01

The ω-phase has been discovered in zirconium-base alloys with the transition metals of Period 4 of the Periodic Table only in Zr-V, Zr-Cr, and Zr-Cu alloys. The first mention about the ω-phase formation in Zr-Cr alloys was given for Zr-4.5 at.%. However, there were no experimental data that confirmed this fact. W.M. Rumball and F.G. Elder presented the X-ray results on the ω-phase formation in Zr-3.9 at.%Cr, but at the present time there are no electron microscope studies of the structure of the ω-phase in this system. Investigations of the features of the ω-phase formation, morphology of the ω-phase and the mechanism of its formation in the different zirconium-base alloys are necessary to establish the common features of the formation of structures with the metastable phases. The task of the present work is to study the conditions and features of the ω-phase formation in the Zr-Cr alloys and the effect of the eutectoid decomposition on the formation of ω-phase. This article is part of the detailed investigations of the feature and condition of the ω-phase formation in zirconium-base alloys with the transition metals of the groups I and V to VIII of the Periodic Table

Interface and properties of the friction stir welded joints of titanium alloy Ti6Al4V with aluminum alloy 6061

International Nuclear Information System (INIS)

Wu, Aiping; Song, Zhihua; Nakata, Kazuhiro; Liao, Jinsun; Zhou, Li

2015-01-01

Highlights: • Friction stir butt welding of titanium alloy Ti6Al4V and aluminum alloy A6061-T6. • Welding parameters affect interfacial microstructure of the joint. • Welding parameters affect the mechanical property of joint and fracture position. • Joining mechanism of Ti6Al4V/A6061 dissimilar alloys by FSW is investigated. - Abstract: Titanium alloy Ti6Al4V and aluminum alloy 6061 dissimilar material joints were made with friction stir welding (FSW) method. The effects of welding parameters, including the stir pin position, the rotating rate and the travel speed of the tool, on the interface and the properties of the joints were investigated. The macrostructure of the joints and the fracture surfaces of the tensile test were observed with optical microscope and scanning electron microscope (SEM). The interface reaction layer was investigated with transmission electron microscopy (TEM). The factors affecting the mechanical properties of the joints were discussed. The results indicated that the tensile strength of the joints and the fracture location are mainly dependent on the rotating rate, and the interface and intermetallic compound (IMC) layer are the governing factor. There is a continuous 100 nm thick TiAl 3 IMC at the interface when the rotating rate is 750 rpm. When the welding parameters were appropriate, the joints fractured in the thermo-mechanically affected zone (TMAZ) and the heat affected zone (HAZ) of the aluminum alloy and the strength of the joints could reach 215 MPa, 68% of the aluminum base material strength, as well as the joint could endure large plastic deformation

Hydrogen storage in TiCr1.2(FeV)x BCC solid solutions

International Nuclear Information System (INIS)

Santos, Sydney F.; Huot, Jacques

2009-01-01

The Ti-V-based BCC solid solutions have been considered attractive candidates for hydrogen storage due to their relatively large hydrogen absorbing capacities near room temperature. In spite of this, improvements of some issues should be achieved to allow the technological applications of these alloys. Higher reversible hydrogen storage capacity, decreasing the hysteresis of PCI curves, and decrease in the cost of the raw materials are needed. In the case of vanadium-rich BCC solid solutions, which usually have large hydrogen storage capacities, the search for raw materials with lower cost is mandatory since pure vanadium is quite expensive. Recently, the substitutions of vanadium in these alloys have been tried and some interesting results were achieved by replacing vanadium by commercial ferrovanadium (FeV) alloy. In the present work, this approach was also adopted and TiCr 1.2 (FeV) x alloy series was investigated. The XRD patterns showed the co-existence of a BCC solid solution and a C14 Laves phase in these alloys. SEM analysis showed the alloys consisted of dendritic microstructure and C14 colonies. The amount of C14 phase increases when the amount of (FeV) decreases in these alloys. Concerning the hydrogen storage, the best results were obtained for the TiCr 1.2 (FeV) 0.4 alloy, which achieved 2.79 mass% of hydrogen storage capacity and 1.36 mass% of reversible hydrogen storage capacity

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti_3Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

International Nuclear Information System (INIS)

Liu, Hongxi; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-01-01

High temperature anti-oxidation TiN/Ti_3Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO_2 laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti_3Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti_3Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti_3Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV_0_._2. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti_3Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti_3Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al_2O_3 and TiO_2. The laser cladding TiN/Ti_3Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti_3Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti_3Al intermetallic coating is mainly composed of α-Ti, TiN and Ti_3Al phases. • The

Study on Ti-6Al-4V Alloy Machining Applying the Non-Resonant Three-Dimensional Elliptical Vibration Cutting

Directory of Open Access Journals (Sweden)

Mingming Lu

2017-10-01

Full Text Available The poor machinability of Ti-6Al-4V alloy makes it hard to process by conventional processing methods even though it has been widely used in military and civilian enterprise fields. Non-resonant three-dimensional elliptical vibration cutting (3D-EVC is a novel cutting technique which is a significant development potential for difficult-to-cut materials. However, few studies have been conducted on processing the Ti-6Al-4V alloy using the non-resonant 3D-EVC technique, the effect of surface quality, roughness, topography and freeform surface has not been clearly researched yet. Therefore, the machinability of Ti-6Al-4V alloy using the non-resonant 3D-EVC apparatus is studied in this paper. Firstly, the principle of non-resonant 3D-EVC technique and the model of cutter motion are introduced. Then the tool path is synthesized. The comparison experiments are carried out with traditional continuous cutting (TCC, two-dimension elliptical vibration cutting (2D-EVC, and the non-resonant 3D-EVC method. The experimental results shown that the excellent surface and lower roughness (77.3 nm could be obtained using the non-resonant 3D-EVC method; the shape and dimension of elliptical cutting mark also relates to the cutting speed and vibration frequency, and the concave/convex spherical surface topography are achieved by non-resonant 3D-EVC in the Ti-6Al-4V alloy. This proved that the non-resonant 3D-EVC technique has the better machinability compared with the TCC and 2D-EVC methods.

Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

Science.gov (United States)

Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

2017-06-01

Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

Fatigue behavior of Ti-6Al-4V alloy modified by plasma immersion ion implantation: temperature effect.

Directory of Open Access Journals (Sweden)

Velloso Verônica

2018-01-01

Full Text Available This research studied Ti-6Al-4V alloy behavior with two (2 different microstructure subjected to nitrogen addition by PIII treatment, with and without sample heating, under cyclic load. PIII conditions, at 390 °C, were DC voltage of 9.5 kV, frequency of 1.5 kHz and pulse of 40 μs. PIII conditions, with sample heating at 800 °C, were 7 kV, 0.4 kHz and 30 μs. Axial fatigue tests were performed on untreated and treated samples for resistance to fatigue comparison. The untreated Ti-6Al-4V had an annealed microstructure, PIII treatment at 390 °C resulted in a microstructure that has no nitride layer or diffusion zone. In the PIII treatment at 800 °C, the microstructure presented nitride layer and diffusion zone. Resistance to fatigue decreased with PIII treatments in both temperatures. At 390 °C, the treatment created deformation regions and cracks on surface due to nitrogen implantation that formed solid solution with titanium and imposed lattice strains on the crystal lattice. At 800 °C, bulk ductility decrease, increasing of αTi proportion in microstructure due to α case formation and the presence of a ceramic layer dropped fatigue resistance of Ti-6A-4V alloy.

The Transverse Rupture Strength in Ti-6Al-4V Alloy Manufactured by Selective Laser Melting

Directory of Open Access Journals (Sweden)

Lai Pang-Hsin

2015-01-01

Full Text Available The objective of this study was to investigate the transverse rupture strength and apparent hardness of selective laser melted Ti-6Al-4V alloys manufactured in the vertical (V and horizontal (H directions. The microstructure and the distribution of alloy elements were examined by optical microscope and electron probe microanalysis, respectively. The results show that the columnar α′ grains are formed along the building direction, and the elemental distributions of Ti, Al, and V are homogeneous in the alloy. The building direction does not sufficiently affect the density and apparent hardness. However, the transverse rupture strengths (TRS are obviously dominated by the building directions investigated in this study. The TRS of an H specimen is significantly superior to that of a V specimen by 48%. This phenomenon can be mainly attributed to the presence of disc-shaped pores.

Hydrogen storage in Ti-Mn-(FeV) BCC alloys

International Nuclear Information System (INIS)

Santos, S.F.; Huot, J.

2009-01-01

Recently, the replacement of vanadium by the less expensive (FeV) commercial alloy has been investigated in Ti-Cr-V BCC solid solutions and promising results were reported. In the present work, this approach of using (FeV) alloys is adopted to synthesize alloys of the Ti-Mn-V system. Compared to the V-containing alloys, the alloys containing (FeV) have a smaller hydrogen storage capacity but a larger reversible hydrogen storage capacity, which is caused by the increase of the plateau pressure of desorption. Correlations between the structure and the hydrogen storage properties of the alloys are also discussed.

Density of liquid Ti-6Al-4V

Directory of Open Access Journals (Sweden)

Schmon Alexander

2017-01-01

Full Text Available Ti-6Al-4V is due to its high strength-density ratio a commonly used alloy in aerospace industry applications. But liquid phase data are scarce as preventing contaminations of the reactive high temperature melt during the investigation process poses a challenge. The thermophysical quantity density is of special interest since it is necessary input parameter in modern numerical casting and solidification simulations. Liquid phase density of Ti-6Al-4V as function of temperature was determined employing a fast resistive pulse-heating technique based on the approach to avoid contaminations of the specimen by extremely reducing the experimental duration of the investigation process. Temperature dependent density of liquid Ti-6Al-4V was determined in a temperature range between 2050 K and 2590 K and is presented.

Synthesis of a TiBw/Ti6Al4V composite by powder compact extrusion using a blended powder mixture

Energy Technology Data Exchange (ETDEWEB)

Lu, Huiyang, E-mail: hl209@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Zhang, Deliang, E-mail: zhangdeliang@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai (China); Gabbitas, Brian, E-mail: briang@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Yang, Fei, E-mail: fyang@waikato.ac.nz [Waikato Center for Advanced Materials, School of Engineering, University of Waikato, Hamilton (New Zealand); Matthews, Steven, E-mail: S.Matthews@massey.ac.nz [School of Engineering and Advanced Technology, Massey University, Auckland (New Zealand)

2014-09-01

Highlights: • TiB/Ti6Al4V composites were prepared from extruded BE powders. • Different starting powders affected the morphologies of TiB whiskers formed in-situ. • A TiB/Ti6Al4V composite with TiB whiskers had good strength and ductility. • The strength and ductility achieved were superior to those obtained by other methods. - Abstract: A Ti–6 wt%Al–4 wt%V alloy (Ti6Al4V) matrix composite, reinforced by in situ synthesized TiB whiskers (TiBw) has been successfully fabricated by powder compact extrusion using a blended powder mixture. The microstructural characterization of the various extruded samples showed that the different starting powders, pre-alloyed powder plus boron powder or titanium plus Al–40V master alloy powder plus boron powder, had a significant effect on the morphology of the in situ synthesized TiB whiskers. It is also evident that the TiB whiskers affect the microstructural evolution of the Ti6Al4V matrix. The tensile test results indicated that the composite with a dispersion of fine TiB whiskers with high aspect ratios exhibited a high ultimate tensile stress (UTS) and yield stress (YS) of 1436 MPa and 1361 MPa, respectively, a reasonably good tensile ductility reflected by an elongation to fracture of 5.6% was also achieved. This is a significant improvement compared with as-extruded monolithic Ti6Al4V alloy produced in this study.

Synthesis of a TiBw/Ti6Al4V composite by powder compact extrusion using a blended powder mixture

International Nuclear Information System (INIS)

Lu, Huiyang; Zhang, Deliang; Gabbitas, Brian; Yang, Fei; Matthews, Steven

2014-01-01

Highlights: • TiB/Ti6Al4V composites were prepared from extruded BE powders. • Different starting powders affected the morphologies of TiB whiskers formed in-situ. • A TiB/Ti6Al4V composite with TiB whiskers had good strength and ductility. • The strength and ductility achieved were superior to those obtained by other methods. - Abstract: A Ti–6 wt%Al–4 wt%V alloy (Ti6Al4V) matrix composite, reinforced by in situ synthesized TiB whiskers (TiBw) has been successfully fabricated by powder compact extrusion using a blended powder mixture. The microstructural characterization of the various extruded samples showed that the different starting powders, pre-alloyed powder plus boron powder or titanium plus Al–40V master alloy powder plus boron powder, had a significant effect on the morphology of the in situ synthesized TiB whiskers. It is also evident that the TiB whiskers affect the microstructural evolution of the Ti6Al4V matrix. The tensile test results indicated that the composite with a dispersion of fine TiB whiskers with high aspect ratios exhibited a high ultimate tensile stress (UTS) and yield stress (YS) of 1436 MPa and 1361 MPa, respectively, a reasonably good tensile ductility reflected by an elongation to fracture of 5.6% was also achieved. This is a significant improvement compared with as-extruded monolithic Ti6Al4V alloy produced in this study

COMPARISON OF THE MECHANICAL RESPONSE OF POROUS TI-6AL-4V ALLOYS PRODUCED BY DIFFERENT COMPACTION TECHNIQUES

Directory of Open Access Journals (Sweden)

G.İpek Selimoğlu

2017-03-01

Full Text Available Porous Ti-6Al-4V alloys are attractive candidates as implant materials due to their good biocompatibility combined with the porous structure leading to increased osseointegration and decreased stiffness. Accordingly, different processing techniques were employed for the production of Ti-6Al-4V foams in the literature. Among these techniques, sintering with space holder is used to produce porous Ti-6Al-4V alloys in this study. Magnesium was employed as the space holder material because of its relatively low boiling point as well as high oxygen affinity. Two different compaction techniques, die compaction with hydraulic pressing and cold isostatic pressing (CIP, were employed for obtaining green compacts. Both spherical and nonspherical Ti-6Al-4V powders were used to investigate the effect of powder shape on compaction. Processed foams were characterized in terms of both microstructural and mechanical aspects in order to investigate the effect of pressing conditions in combination with powder characteristics. It was observed that NS-CIP foam, which was produced by compacting nonspherical powders by cold isostatic press, has the highest strength. However, the S-DP foam, which was produced by die-pressing of spherical powders, has the highest toughness.

Adhesion measurement of highly-ordered TiO2 nanotubes on Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Masoud Sarraf

2017-12-01

Full Text Available Self-assembled nanotubular arrays on Ti alloys could be used for more effective implantable devices in various medical approaches. In the present work, the adhesion of TiO2 nanotubes (TiO2 NTs on Ti-6Al-4V (Ti64 was investigated by laser spallation and scratch test techniques. At first, electrochemical anodization was performed in an ammonium fluoride solution dissolved in a 90:10 ethane-1,2-diol (ethylene glycol and water solvent mixture. This process was performed at room temperature (23 °C at a steady potential of 60 V for 1 h. Next, the TiO2 nanotubes layer was heat-treated to improve the adhesion of the coating. The formation of selforganized TiO2 nanotubes as well as the microstructural evolution, are strongly dependent on the processing parameters and subsequent annealing. From microscopic analysis, highly oriented arrays of TiO2 nanotubes were grown by thermal treatment for 90 min at 500 °C. Further heat treatment above 500 °C led to the detachment of the nanotubes and the complete destruction of the nanotubes occurred at temperature above 700 °C. Scratch test analysis over a constant scratch length (1000 µm indicated that the failure point was shifted from 247.4 to 557.9 µm while the adhesion strength was increased from ∼862 to ∼1814 mN after annealing at 500 °C. The adhesion measurement determined by laser spallation technique provided an intrinsic adhesion strength of 51.4 MPa for the TiO2 nanotubes on the Ti64 substrate.

Effect of trace solute hydrogen on the fatigue life of electron beam welded Ti-6Al-4V alloy joints

Energy Technology Data Exchange (ETDEWEB)

Tao, Junhui; Hu, Shubing, E-mail: 187352581@qq.com; Ji, Longbo

2017-01-27

This paper describes an experimental hydrogenating treatment on a Ti-6Al-4V fatigue specimen containing an electron beam welding joint. The effect of trace solute hydrogen on the microstructures and fatigue behavior of welded Ti-6Al-4V alloy joints was investigated using an optical microscope, X-ray diffractometer, scanning electron microscope, transmission electron microscope and other methodologies. The results demonstrated that no hydride formed in the hydrogenated weld joint at a hydrogen concentration of less than 0.140 wt%. Internal hydrogen, which was present in the alloy in the form of solid solution atoms, caused lattice distortion in the β phase. The fatigue properties of the Ti-6Al-4V weld joint hydrogenated with trace solute hydrogen decreased significantly. The solute hydrogen led to an increase in the brittleness of the hydrogenated weld joint. The dislocation densities in the secondary α and β phase were higher. Fatigue cracks nucleated at the α/β interfaces. The effect of solute hydrogen accelerated the separation of the persistent slip bands, which decreased the threshold required for fatigue crack growth. Solute hydrogen also accelerated the fatigue crack growth rate. These two factors contributed to the degradation of the fatigue life in the electron beam welded Ti-6Al-4V alloy joints.

Dry sliding wear behavior of laser clad TiVCrAlSi high entropy alloy coatings on Ti–6Al–4V substrate

International Nuclear Information System (INIS)

Huang, Can; Zhang, Yongzhong; Vilar, Rui; Shen, Jianyun

2012-01-01

Highlights: ► TiVCrAlSi high entropy alloy coatings were obtained on Ti–6Al–4V by laser cladding. ► (Ti,V) 5 Si 3 forms because the formation is accompanied of large variation on enthalpy. ► Wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. ► The wear mechanism is investigated. -- Abstract: Approximately equimolar ratio TiVCrAlSi high entropy alloy coatings has been deposited by laser cladding on Ti–6Al–4V alloy. The analysis of the microstructure by scanning electron microscopy (SEM) shows that the coating is metallurgically bonded to the substrate. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analyses show that TiVCrAlSi coating is composed of precipitates of (Ti,V) 5 Si 3 dispersed in a body-centered cubic (BCC) matrix. Intermetallic compound (Ti,V) 5 Si 3 forms because the formation is accompanied by larger variation on enthalpy, which may offset the entropy term. The dry sliding wear tests show that the wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. The enhancement of the wear resistance is explained by the presence of the hard silicide phase dispersed in a relatively ductile BCC matrix, which allows sliding wear to occur in the mild oxidative regime for a wide range of testing conditions.

Structure and grindability of cast Ti-5Cr-xFe alloys

International Nuclear Information System (INIS)

Hsu, H.-C.; Pan, C.-H.; Wu, S.-C.; Ho, W.-F.

2009-01-01

The purpose of this study was to investigate the structure, microhardness and grindability of Ti-5Cr and a series of ternary Ti-5Cr-xFe alloys with 0.1, 0.5, 1, 3 and 5 wt.% Fe, respectively. This study evaluated the phase and structure of Ti-5Cr and Ti-5Cr-xFe alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. In addition, grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min at each of the four rotational speeds of the wheel (500, 750, 1000 or 1200 m/min), with the goal of developing a titanium alloy with better machinability than commercially pure titanium (c.p. Ti). The results showed that the structure of Ti-5Cr-xFe alloys is sensitive to the Fe content. With Fe contents higher than 0.5 wt.%, the equi-axed β phase is entirely retained, while ω phase was found in the Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The largest quantity of ω phase and highest microhardness were found in Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The grinding rates of the Ti-5Cr and Ti-5Cr-xFe alloys showed a similar tendency to the microhardness. The Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys exhibited the best grindability, especially at 500, 750 and 1000 m/min. Furthermore, the grindability of the tested metals increased in proportion to grinding speed up to 1000 m/min, with a decrease after 1200 m/min. This study concluded that Fe may be used to harden titanium and improve the grindability

The effect of aluminum content on phase constitution and heat treatment behavior of Ti-Cr-Al alloys for healthcare application

International Nuclear Information System (INIS)

Sugano, Daisuke; Ikeda, Masahiko

2005-01-01

As life expectancy steadily increases, developing reliable functional materials for healthcare applications gains importance. Titanium and its alloys, while attractive for such applications, are expensive. The present investigation suggests that it may be possible to reduce costs by using new, low-cost beta Ti alloys. To assess their reliability, the heat treatment behavior of beta Ti alloys, Ti-7 mass% Cr with varying Al content (0%, 1.5%, 3.0% and 4.5%), was investigated through electrical resistivity and Vickers hardness measurements. In the Ti-7Cr-0Al alloy quenched from 1173 K, only the beta phase was identified by X-ray diffraction (XRD). In Ti-7Cr-1.5 to 4.5 Al alloys, XRD detected both beta and orthorhombic martensite. On isochronal heat treatment behavior of Ti-7Cr-3.0, 4.5 Al alloys, resistivity at liquid nitrogen temperature and resistivity ratio increased between 423 and 523 K.These increases are due to reverse transformation of orthorhombic martensite to the metastable beta phase

Tribological investigations of surface treated Ti6Al4V

International Nuclear Information System (INIS)

Rueck, D.M.; Schminke, A.; Schmidt, H.; Soltani-Farshi, M.; Baumann, H.; Fink, U.; Richter, E.

1998-05-01

The tribological couple of the titanium alloy Ti6Al4V and ultrahigh molecular weight polyethylene (UHMWPE) is used for hip and knee joint prostheses. It is known that surface treatment of the titanium alloy Ti6Al4V by ion implantation of various elements can improve the wear behavior of such prostheses. The results of tribological tests, performed in Ringer solution with a ring-on-disc tester, show that oxygen in the implanted near surface region has a pronounced influence on the wear performance. Oxygen can be introduced into the surface by different mechanisms: either by direct implantation of oxygen ions or by indiffusion during the implantation of other elements like nitrogen or carbon at higher temperatures. The influence of the oxygen content in the near surface region of implanted and nonimplanted Ti6Al4V on the tribological performance is discussed in detail. (orig.)

The electrochemical properties of Zr-Ti-V-Ni-Mn hydrogen storage alloys with various compositions for an electrode of Ni-MH secondary battery

Energy Technology Data Exchange (ETDEWEB)

Choi, Seung Jun; Jung, So Yi; Park, Choong Nyeon [Dept. of Metallurgical Engineering, Chonnam National University, Kwangju (Korea)

1999-12-01

Effects of alloy modification for the Zr{sub 0.7}Ti{sub 0.3}V{sub 0.4}Ni{sub 1.2}Mn{sub 0.4} alloy as an electrode materials have been investigated. When Ti in the alloy was partially substituted by Zr, the hydrogen storage capacity and subsequently the discharge capacity increased significantly, however, the activation characteristic and rate capability decreased. By substituting Mn with other elements (Cr, Co and Fe) in the alloy, discharge capacity decreased but the cycle life and rate capability were improved. Considering both the discharge capacity, the high rate discharge property and cycle life, the Zaire.{sub 7}Ti{sub 0.3}V{sub 0.4}Ni{sub 1.2}Mn{sub 0.3}Cr{sub 0.1} alloy among the alloys subjected to the test was found to be a prominent alloy for a practical usage. 11 refs., 5 figs., 2 tabs.

Laser cladding Ni-base composite coating on titanium alloy with pre-placed B4C+NiCoCrAlY

International Nuclear Information System (INIS)

Qingwu Meng; Lin Geng; Zhenzhu Zheng

2005-01-01

Using a CO 2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B 4 C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratio of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B 4 C and Ti during in-situ producing TiB 2 and TiC. The Ni-base composite coating is strengthened with TiB 2 and TiC reinforcement phases. Vickers hardness tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy. (orig.)

Morphology, deformation, and defect structures of TiCr2 in Ti-Cr alloys

International Nuclear Information System (INIS)

Chen, K.C.; Allen, S.M.; Livingston, J.D.

1992-01-01

The morphologies and defect structures of TiCr 2 in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr 2 . The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability

Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

Energy Technology Data Exchange (ETDEWEB)

Keddam, Mourad, E-mail: keddam@yahoo.fr [Laboratoire de Technologie des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P. No. 32, 16111 El-Alia, Bab-Ezzouar, Algiers (Algeria); Taktak, Sukru [Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, ANS Campus, 03200, Afyonkarahisar (Turkey)

2017-03-31

Highlights: • Titanium boride layers were produced by plasma paste boriding on Ti6Al4V at 973–1073 K. • Formation rates of the Ti boride layers have parabolic character at all temperatures. • Boron diffusivities were estimated using a diffusion model including incubation times. • Activation energies of boron in TiB{sub 2} and TiB were 136 and 63 kJ/mol respectively. - Abstract: The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973–1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB{sub 2} top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB{sub 2} and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB{sub 2} and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB{sub 2} and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol{sup −1}, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

Microstructure and high temperature oxidation resistance of in-situ synthesized TiN/Ti{sub 3}Al intermetallic composite coatings on Ti6Al4V alloy by laser cladding process

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongxi, E-mail: piiiliuhx@sina.com; Zhang, Xiaowei; Jiang, Yehua; Zhou, Rong

2016-06-15

High temperature anti-oxidation TiN/Ti{sub 3}Al intermetallic composite coatings were fabricated with the powder and AlN powder on Ti6Al4V titanium alloy surface by 6 kW transverse-flow CO{sub 2} laser apparatus. The chemical composition, morphology and microstructure of the TiN/Ti{sub 3}Al composite coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high temperature oxidation resistance of TiN/Ti{sub 3}Al coating, the isothermal oxidation test was performed in a high temperature resistance furnace at 600 °C and 800 °C, respectively. The result shows that the composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like or dendrites), with an even distribution in Ti{sub 3}Al matrix. It indicates that a physical and chemical reaction between Ti powder and AlN powder has completely occurred under the laser irradiation condition. In addition, the microhardness of the TiN/Ti3Al intermetallic composite coating is 3.4 times higher than that of the Ti6Al4V alloy substrate and reaches 844 HV{sub 0.2}. The high temperature oxidation behavior test reveals that the high temperature oxidation resistance of TiN/Ti{sub 3}Al composite coating is much better than that of titanium alloy substrate. The excellent high temperature oxidation resistance of TiN/Ti{sub 3}Al intermetallic composite coating is attributed to the formation of reinforced phases TiN, Al{sub 2}O{sub 3} and TiO{sub 2}. The laser cladding TiN/Ti{sub 3}Al intermetallic composite coating is anticipated to be a promising high temperature oxidation resistance coating for Ti6Al4V alloy. - Highlights: • In-situ TiN/Ti{sub 3}Al composite coating was synthesized on Ti6Al4V alloy by laser cladding. • The influence of Ti and AlN molar ratio on the microstructure of the coating was studied. • The TiN/Ti{sub 3}Al intermetallic

On the Correlation between Morphology of alpha and Its Crystallographic Orientation Relationship with TiB and Beta in Boron Containing Ti-5Al-5Mo-5V-3Cr-0.5Fe Alloy (Preprint)

Science.gov (United States)

2012-01-01

orientation microscopy studies on a boron containing version of the commercial Ti- 5Al-5Mo-5V-3Cr-0.5Fe ( Ti5553 ) alloy. 15. SUBJECT TERMS Ti5553 ...of the commercial Ti-5Al-5Mo-5V-3Cr-0.5Fe ( Ti5553 ) alloy. Keywords: Ti5553 , TiB, EBSD, crystallography, orientation relationship. Paper There has...absence of orientation relationships between the α, β and TiB phases, on the morphology of α nucleating from TiB in the Ti5553 alloy.. The base

Biocorrosion of TiO2 nanoparticle coating of Ti-6Al-4V in DMEM under specific in vitro conditions

Science.gov (United States)

Höhn, Sarah; Virtanen, Sannakaisa

2015-02-01

A TiO2 nanoparticle coating was prepared on a biomedical Ti-6Al-4V alloy using "spin-coating" technique with a colloidal suspension of TiO2 nanopowders with the aim to optimize the surface morphology (e.g., roughness) for improved biocompatibility. The influence of a TiO2 nanoparticle (NP) coating on the corrosion behavior, metal ion release, and biomimetic apatite formation was studied in DMEM, at 37.5 °C with a continuous supply of 5% CO2. Electrochemical impedance spectroscopy measurements indicate a formation of a new layer on the surface of the NP-coated sample upon 28 days immersion in DMEM. Scanning electron microscopy (SEM) and X-ray spectroscopy confirm that the surface of the NP-coated Ti-6Al-4V shows a complete coverage by a Ca-phosphate layer in contrast to the non-coated Ti-6Al-4V alloy. Hence, the TiO2-NP coating strongly enhances biomimetic apatite formation on the alloy surface. In addition, the TiO2-NP coating can efficiently reduce Al-release from the alloy, for which the bare Ti-6Al-4V alloy is significant for at least 28 days of immersion in DMEM.

Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

Science.gov (United States)

Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

2010-11-01

A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

Topographic and Electrochemical Ti6Al4V Alloy Surface Characterization in Dry and Wet Reciprocating Sliding

Directory of Open Access Journals (Sweden)

Z. Doni

2013-09-01

Full Text Available This present paper shows the behavior of functional integrity of the state Ti6Al4V alloy under reciprocating sliding wear conditions in acomparative way for two different counter materials, steel and ceramicballs in dry and corrosive environment (3.5% NaCl. The surface integrity analysis of the dry reciprocating wear tests was based on the evolution of The roughness parameters with the applied load. In the case of reciprocating wear tests in corrosive environment the surface integrity analysis was based on electrochemical parameters. Comparative analysis of the evolution of the roughness parameters with the applied load shows a higher stability of the Ti6Al4V/Al2O3 contact pair, while from the point of view of the electrochemical parameters the Tribological properties are worse than Ti6Al4V/steel ball contact pair.

Structural characterization and electrochemical behavior of 45S5 bioglass coating on Ti6Al4V alloy for dental applications

Energy Technology Data Exchange (ETDEWEB)

López, M.M. Machado, E-mail: machadolopez23@gmail.com [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “U”, C.P. 58000, Morelia, Michoacán, México (Mexico); Fauré, J. [Laboratoire Ingénierie et Sciences des Matériaux (LISM EA 4695) - Université de Reims Champagne-Ardenne, 21 rue Clément Ader, Reims, BP 138 Cedex 02, 51685 France (France); Cabrera, M.I. Espitia [Facultad de ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “D”, C.P. 58000, Morelia, Michoacán, México (Mexico); García, M.E. Contreras, E-mail: eucontre@umich.mx [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, C.U. Edificio “U”, C.P. 58000, Morelia, Michoacán, México (Mexico)

2016-04-15

Graphical abstract: - Highlights: • Bioglass 45S5 nanostructured films were obtained by colloidal electrophoretic deposition (CEDP) method, proposed in this work, on Ti6Al4 V substrates. • Ti6Al4 V corrosion resistance in Hank's solution was increased with bioglass 45S5 coating. • Crystalline phases of 45S5 bioglass xerogels were obtained and characterized by XRD. • The model of chemical anchoring between Ti6Al4 V and bioglass 45S5 is proposed. - Abstract: In the present work, 45S5 bioglass coatings were deposited on the Ti6Al4 V alloy substrate through the cathodic colloidal electrophoretic deposition process (CEDP) proposed in this work. The coatings were thermally treated at temperatures of 500, 600, 700, and 800 °C for 2 h, and their structure was characterized by FESEM and DRX. Nanostructure and phase evolution of the coatings and xerogels was followed as a function of temperature. The corrosion resistance of the Ti6Al4 V alloy and the 45S5/Ti6Al4 V coating was studied by means of Tafel extrapolation in Hank's solution, at 37 °C, simulating the conditions inside the mouth. The 45S5 bioglass coatings displayed an amorphous nanostructure at lower temperatures, and partial crystallization at higher temperatures. An increase in the corrosion resistance was observed in the 45S5/Ti6l4 V coating treated at 700 °C because it reduced the i{sub corr}, and there was a change in the E{sub corr} towards more noble values. A model of the chemical anchorage of the 45S5 bioglass coating on Ti6Al4 V was proposed.

Crystal structures of lazulite-type oxidephosphates TiIIITiIV3O3(PO4)3 and MIII4TiIV27O24(PO4)24 (MIII=Ti, Cr, Fe)

International Nuclear Information System (INIS)

Schoeneborn, M.; Glaum, R.; Reinauer, F.

2008-01-01

Single crystals of the oxidephosphates Ti III Ti IV 3 O 3 (PO 4 ) 3 (black), Cr III 4 Ti IV 27 O 24 (PO 4 ) 24 (red-brown, transparent), and Fe III 4 Ti IV 27 O 24 (PO 4 ) 24 (brown) with edge-lengths up to 0.3 mm were grown by chemical vapour transport. The crystal structures of these orthorhombic members (space group F2dd ) of the lazulite/lipscombite structure family were refined from single-crystal data [Ti III Ti IV 3 O 3 (PO 4 ) 3 : Z=24, a=7.3261(9) A, b=22.166(5) A, c=39.239(8) A, R 1 =0.029, wR 2 =0.084, 6055 independent reflections, 301 variables; Cr III 4 Ti IV 27 O 24 (PO 4 ) 24 : Z=1, a=7.419(3) A, b=21.640(5) A, c=13.057(4) A, R 1 =0.037, wR 2 =0.097, 1524 independent reflections, 111 variables; Fe III 4 Ti IV 27 O 24 (PO 4 ) 24 : Z=1, a=7.4001(9) A, b=21.7503(2) A, c=12.775(3) A, R 1 =0.049, wR 2 =0.140, 1240 independent reflections, 112 variables). For Ti III Ti IV O 3 (PO 4 ) 3 a well-ordered structure built from dimers [Ti III,IV 2 O 9 ] and [Ti IV,IV 2 O 9 ] and phosphate tetrahedra is found. The metal sites in the crystal structures of Cr 4 Ti 27 O 24 (PO 4 ) 24 and Fe 4 Ti 27 O 24 (PO 4 ) 24 , consisting of dimers [M III Ti IV O 9 ] and [Ti IV,IV 2 O 9 ], monomeric [Ti IV O 6 ] octahedra, and phosphate tetrahedra, are heavily disordered. Site disorder, leading to partial occupancy of all octahedral voids of the parent lipscombite/lazulite structure, as well as splitting of the metal positions is observed. According to Guinier photographs Ti III 4 Ti IV 27 O 24 (PO 4 ) 24 (a=7.418(2) A, b=21.933(6) A, c=12.948(7) A) is isotypic to the oxidephosphates M III 4 Ti IV 27 O 24 (PO 4 ) 24 (M III : Cr, Fe). The UV/vis spectrum of Cr 4 Ti 27 O 24 (PO 4 ) 24 reveals a rather small ligand-field splitting Δ o =14,370 cm -1 and a very low nephelauxetic ratio β=0.72 for the chromophores [Cr III O 6 ] within the dimers [Cr III Ti IV O 9 ]. - Graphical abstract: Single crystals of the oxidephosphates Ti III Ti IV 3 O 3 (PO 4 ) 3 (black), Cr III 4 Ti IV 27 O

Influence of sintering temperature on mechanical properties of spark plasma sintered pre-alloyed Ti-6Al-4 V powder

Energy Technology Data Exchange (ETDEWEB)

Muthuchamy, A.; Patel, Paridh; Rajadurai, M. [VIT Univ., Vellore, Tamil Nadu (India); Chaurisiya, Jitendar K. [NIT, Suratkal (India); Annamalai, A. Raja [VIT Univ., Vellore, Tamil Nadu (India). Centre for Innovative Manufacturing Research

2018-04-01

Spark plasma sintering provides faster heating that can create fully, or near fully, dense samples without significant grain growth. In this study, pre-alloyed Ti-6Al-4 V powder compact samples produced through field assisted sintering in a spark plasma sintering machine are compared as a function of consolidation temperature. The effect of sintering temperature on the densification mechanism, microstructural evolution and mechanical properties of spark plasma sintered Ti-6Al-4 V alloy compacts was investigated in detail. The compact, sintered at 1100 C, exhibited near net density, highest hardness and strength as compared to the other compacts processed at a temperature lower than 1100 C.

Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

Science.gov (United States)

Shah, Furqan A; Trobos, Margarita; Thomsen, Peter; Palmquist, Anders

2016-05-01

Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required. Copyright © 2016 Elsevier B.V. All rights reserved.

Mode I and mixed I/III crack initiation and propagation behavior of V-4Cr-4Ti alloy at 25{degrees}C

Energy Technology Data Exchange (ETDEWEB)

Li, H.X.; Kurtz, R.J.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

1997-04-01

The mode I and mixed-mode I/III fracture behavior of the production-scale heat (No. 832665) of V-4Cr-4Ti has been investigated at 25{degrees}C using compact tension (CT) specimens for a mode I crack and modified CT specimens for a mixed-mode I/III crack. The mode III to mode I load ratio was 0.47. Test specimens were vacuum annealed at 1000{degrees}C for 1 h after final machining. Both mode I and mixed-mode I/III specimens were fatigue cracked prior to J-integral testing. It was noticed that the mixed-mode I/III crack angle decreased from an initial 25 degrees to approximately 23 degrees due to crack plane rotation during fatigue cracking. No crack plane rotation occurred in the mode I specimen. The crack initiation and propagation behavior was evaluated by generating J-R curves. Due to the high ductility of this alloy and the limited specimen thickness (6.35 mm), plane strain requirements were not met so valid critical J-integral values were not obtained. However, it was found that the crack initiation and propagation behavior was significantly different between the mode I and the mixed-mode I/III specimens. In the mode I specimen crack initiation did not occur, only extensive crack tip blunting due to plastic deformation. During J-integral testing the mixed-mode crack rotated to an increased crack angle (in contrast to fatigue precracking) by crack blunting. When the crack initiated, the crack angle was about 30 degrees. After crack initiation the crack plane remained at 30 degrees until the test was completed. Mixed-mode crack initiation was difficult, but propagation was easy. The fracture surface of the mixed-mode specimen was characterized by microvoid coalescence.

Influence of the final temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy

Directory of Open Access Journals (Sweden)

Pedro César Garcia Oliveira

2007-02-01

Full Text Available The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430ºC (control group, 480ºC and 530ºC. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430ºC, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50 and (352.95, 339.36, 344.76 - mean 345.69, respectively. The values were submitted to Analysis of Variance (ANOVA and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

Electrochemical behavior of Ti and Ti6Al4V in aqueous solutions of citric acid containing halides

Directory of Open Access Journals (Sweden)

Anelise Marlene Schmidt

2006-12-01

Full Text Available This paper reports on an investigation of the electrochemical behavior of Ti grade 2 and Ti6Al4V alloy in aqueous citric acid solutions with pH 2.0 containing halide ions. Voltammetric studies of Ti and the alloy in citric acid, with and without chloride ions, indicate that the Ti and Ti alloy presented a passive behavior in the test solutions used. Pitting was observed at 3.0 and 2.5 V/SCE for Ti and Ti6Al4V, respectively, when bromide ions were added to the solution. In solutions containing fluoride ions, dissolution of the film occurred at potentials close to - 1.0 V/SCE in both electrodes. The iodide ions oxidized on the passive oxide film at potentials close to 1.0 V/SCE. EIS results of the materials in citric acid solutions containing chloride ions revealed that the film's resistance increased as the applied potential rose from 0 to 1.0 V. In bromide-containing solutions, breakdown of the film was confirmed at potentials above 2.0 V/SCE in both electrodes. These results suggest film reformation for Ti and the alloy in solutions containing fluoride at potentials within the passive region.

Effect of Ti solute on the recovery of cold-rolled V-Ti alloys

International Nuclear Information System (INIS)

Leguey, T.; Munoz, A.; Pareja, R.

1999-01-01

The recovery characteristics of cold-rolled pure V and V-Ti alloys with compositions of 0.3, 1 and 4.5 at.% Ti have been investigated by positron annihilation spectroscopy. The recovery is accomplished in two stages. Fifty percent cold rolling induces the formation of microvoids in V-0.3Ti and V-1Ti but not in V-4.5Ti. The first recovery stage in pure V, V-0.3Ti and V-1Ti starts with the dissolution of microvoids. The recovery curves of the annihilation parameters for the alloys indicate the formation of Ti-rich precipitates during the first recovery stage. These precipitates act as very efficient vacancy sinks. The second recovery stage starting for annealing temperatures above ≅1150 K is attributed to annealing of vacancies associated to the precipitates. (orig.)

Stability and migration of vacancy in V–4Cr–4Ti alloy: Effects of Al, Si, Y trace elements

International Nuclear Information System (INIS)

Zhang, Chong; Zhang, Pengbo; Li, Ruihuan; Zhao, Jijun; Dong, Chuang

2013-01-01

Addition of trace amounts of Al, Si and Y into V–4Cr–4Ti alloy is beneficial for the mechanical properties under irradiation. It is thus important to investigate the influence of solute/trace elements on stabilities, energetics and diffusion behaviors of vacancy defects. We performed first-principles calculations to evaluate vacancy–solute/trace interaction inside dilute V–X (X = Ti, Cr, Al, Si, Y) and V–4Cr–4Ti–(Al, Si, Y) alloys. With addition of Si and Y, vacancy-based complexes tend to form near Ti–Si and Ti–Y pairs, while the effect of Al is negligible. Moreover, diffusion coefficients of solute/trace element in vanadium were derived using nine-frequency model. With high binding energy and low diffusion coefficient, Si atom is strongly attractive to vacancy in vanadium matrix. Our theoretical results suggest that the interactions between vacancy and solute/trace elements play some role in the evolution of microstructures inside vanadium alloys

Influence of Material Microstructures in Micromilling of Ti6Al4V Alloy

Directory of Open Access Journals (Sweden)

Claudio Giardini

2013-09-01

Full Text Available In the most recent decades the introduction of unconventional machining processes allowed the development of micromachining techniques. In this work, the influence of material microstructures on the micromilling process was investigated. Ti6Al4V alloy was selected as workpiece material since it is a very common material for micro applications and because its duplex microstructure can be easily changed by proper thermal treatments. Four different microstructures (namely bimodal, fully equiaxed, fully lamellar and mill annealed were obtained through recrystallization annealing treatments carried out at different times and temperatures. The mechanical properties of the samples were assessed by microhardness measurements. Nano-indentations were also performed on single grains to understand how the different hardness of phases and structures present in the Ti6Al4V alloy can affect the micromilling process. Microchannels using two flute flat end mills with a diameter equal to 200 µm were realized on the treated samples. Two different feed-per-tooth values were used during the tests. Cutting force, channel shape and burr dimension were investigated. Morphological and energy dispersive spectroscopy (EDS analyses were performed on tools by means of a scanning electron microscope (SEM: in this way the phenomena mainly influencing the tool status were also identified. Lower cutting forces and reduced tool wear were observed when working fully lamellar microstructures compared to the other ones.

Study of Tool Wear Mechanisms and Mathematical Modeling of Flank Wear During Machining of Ti Alloy (Ti6Al4V)

Science.gov (United States)

Chetan; Narasimhulu, A.; Ghosh, S.; Rao, P. V.

2015-07-01

Machinability of titanium is poor due to its low thermal conductivity and high chemical affinity. Lower thermal conductivity of titanium alloy is undesirable on the part of cutting tool causing extensive tool wear. The main task of this work is to predict the various wear mechanisms involved during machining of Ti alloy (Ti6Al4V) and to formulate an analytical mathematical tool wear model for the same. It has been found from various experiments that adhesive and diffusion wear are the dominating wear during machining of Ti alloy with PVD coated tungsten carbide tool. It is also clear from the experiments that the tool wear increases with the increase in cutting parameters like speed, feed and depth of cut. The wear model was validated by carrying out dry machining of Ti alloy at suitable cutting conditions. It has been found that the wear model is able to predict the flank wear suitably under gentle cutting conditions.

Mechanisms of improving the cyclic stability of V-Ti-based hydrogen storage electrode alloys

International Nuclear Information System (INIS)

Miao He; Wang Weiguo

2010-01-01

Research highlights: → The corrosion resistance of V-based phase is much lower than that of C14 Laves phase of V-Ti-based alloys. → The addition of Cr which mostly distributes in V-based phase can effectively increase the anti-corrosion ability of V-Ti-based alloys. → The addition of Cr which mostly distributes in V-based phase can effectively increase the anti-corrosion ability of V-Ti-based alloys. - Abstract: In this work, the mechanisms of improving the cyclic stability of V-Ti-based hydrogen storage electrode alloys were investigated systemically. Several key factors for example corrosion resistance, pulverization resistance and oxidation resistance were evaluated individually. The V-based solid solution phase has much lower anti-corrosion ability than C14 Laves phase in KOH solution, and the addition of Cr in V-Ti-based alloys can suppress the dissolution of the main hydrogen absorption elements of the V-based phase in the alkaline solution. During the charge/discharge cycling, the alloy particles crack or break into several pieces, which accelerates their corrosion/oxidation and increases the contact resistance of the alloy electrodes. Proper decreasing the Vickers hardness and enhancing the fracture toughness can increase the pulverization resistance of the alloy particles. The oxidation layer thickness on the alloy particle surface obviously increases during charge/discharge cycling. This deteriorates their electro-catalyst activation to the electrochemical reaction, and leads to a quick degradation. Therefore, enhancing the oxide resistance can obviously improve the cyclic stability of V-Ti-based hydrogen storage electrode alloys.

Manipulation of the osteoblast response to a Ti 6Al 4V titanium alloy using a high power diode laser

Science.gov (United States)

Hao, L.; Lawrence, J.; Li, L.

2005-07-01

To improve the bone integration of titanium-based implants a high power diode laser (HPDL) was used to modify the material for improved osteoblast cell response. The surface properties of un-treated and HPDL treated samples were characterized. Contact angles for the un-treated and the HPDL modified titanium alloy (Ti-6Al-4V) were determined with selected biological liquids by the sessile drop technique. The analysis revealed that the wettability of the Ti-6Al-4V improved after HPDL laser treatment, indicating that better interaction with the biological liquids occurred. Moreover, an in vitro human fetal osteoblast cells (hFOB 1.19) evaluation revealed a more favourable cell response on the HPDL laser treated Ti-6Al-4V alloy than on either un-treated sample or a mechanically roughened sample. It was consequently determined that the HPDL provides more a controllable and effective technique to improve the biocompatibility of bio-metals.

Effects of Plasma ZrN Metallurgy and Shot Peening Duplex Treatment on Fretting Wear and Fretting Fatigue Behavior of Ti6Al4V Alloy.

Science.gov (United States)

Tang, Jingang; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing; Yu, Shouming

2016-03-23

A metallurgical zirconium nitride (ZrN) layer was fabricated using glow metallurgy using nitriding with zirconiuming prior treatment of the Ti6Al4V alloy. The microstructure, composition and microhardness of the corresponding layer were studied. The influence of this treatment on fretting wear (FW) and fretting fatigue (FF) behavior of the Ti6Al4V alloy was studied. The composite layer consisted of an 8-μm-thick ZrN compound layer and a 50-μm-thick nitrogen-rich Zr-Ti solid solution layer. The surface microhardness of the composite layer is 1775 HK 0.1 . A gradient in cross-sectional microhardness distribution exists in the layer. The plasma ZrN metallurgical layer improves the FW resistance of the Ti6Al4V alloy, but reduces the base FF resistance. This occurs because the improvement in surface hardness results in lowering of the toughness and increasing in the notch sensitivity. Compared with shot peening treatment, plasma ZrN metallurgy and shot peening composite treatment improves the FW resistance and enhances the FF resistance of the Ti6Al4V alloy. This is attributed to the introduction of a compressive stress field. The combination of toughness, strength, FW resistance and fatigue resistance enhance the FF resistance for titanium alloy.

Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo

Energy Technology Data Exchange (ETDEWEB)

Zhao, Bingjing; Wang, Hong [Department of Stomatology, General Hospital of the PLA, Beijing (China); Department of Stomatology, The Second Affiliated Stomatological Hospital of Liaoning Medical University (China); Qiao, Ning [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing (China); Wang, Chao [School of Medicine, Nankai University, Tianjin 300071 (China); Hu, Min, E-mail: humin48@vip.163.com [Department of Stomatology, General Hospital of the PLA, Beijing (China)

2017-01-01

The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (< 1.5 V) and EBM specimen was the best under the high electric potential (> 1.5 V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. - Highlights: • EBM and SLM Ti-6Al-4V alloy have good corrosion resistance, and both of them can be applied in vivo. • SLM Ti-6Al-4V alloy was more suitable for implantation in vivo than that of EBM Ti-6Al-4V alloy. • The crevice corrosion resistance of the EBM specimen is the best. • EBM and SLM specimens can form oxide film.

The effect of laser welding process parameters on the mechanical and microstructural properties of V-4CR-4TI structural materials

International Nuclear Information System (INIS)

Reed, C. B.; Natesan, K.; Xu, Z.; Smith, D. L.

1999-01-01

V-Cr-Ti alloys are among the leading candidate materials for the frost wall and other structural materials applications in fusion power reactors because of several important advantages including inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation-induced swelling and damage [1]. However, weldability of these alloys in general must be demonstrated, and laser welding, specifically, must be developed. Laser welding is considered to be an attractive process for construction of a reactor due to its high penetrating power and potential flexibility. This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. The effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld

Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

Energy Technology Data Exchange (ETDEWEB)

Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

1997-04-01

A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.

Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

International Nuclear Information System (INIS)

Natesan, K.; Soppet, W.K.

1997-01-01

A test program is in progress to evaluate the effect of oxygen at low pO 2 on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO 2 at 500 degrees C and reannealed in vacuum at 500 degrees C in environments with various pO 2 levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO 2 environments

Investigation of the HA film deposited on the porous Ti6Al4V alloy prepared via additive manufacturing

International Nuclear Information System (INIS)

Surmeneva, M; Chudinova, E; Syrtanov, M; Surmenev, R; Koptioug, A

2015-01-01

This study is focused on the use of radio frequency magnetron sputtering to modify the surface of porous Ti6Al4V alloy fabricated via additive manufacturing technology. The hydroxyapatite (HA) coated porous Ti6Al4V alloy was studied in respect with its chemical and phase composition, surface morphology, water contact angle and hysteresis, and surface free energy. Thin nanocrystalline HA film was deposited while its structure with diamond-shaped cells remained unchanged. Hysteresis and water contact angle measurements revealed an effect of the deposited HA films, namely an increased water contact angle and contact angle hysteresis. The increase of the contact angle of the coating-substrate system compared to the uncoated substrate was attributed to the multiscale structure of the resulted surfaces. (paper)

A comparison of corrosion, tribocorrosion and electrochemical impedance properties of pure Ti and Ti6Al4V alloy treated by micro-arc oxidation process

Science.gov (United States)

Fazel, M.; Salimijazi, H. R.; Golozar, M. A.; Garsivaz jazi, M. R.

2015-01-01

In this paper, the micro-arc oxidation (MAO) coatings were performed on pure Ti and Ti6Al4V samples at 180 V. The results indicated that unlike the volcanic morphology of oxide layer on pure Ti, a cortex-like morphology with irregular vermiform slots was seen on MAO/Ti6Al4V sample. According to polarization curves, the corrosion resistance of untreated samples was significantly increased by MAO process. The electrochemical impedance spectroscopy analysis showed a lower capacitance of barrier layer (led to higher resistance) for MAO/Ti specimens. This indicates that corrosive ions diffusion throughout the oxide film would be more difficult resulted in a higher corrosion resistance. Tribocorrosion results illustrated that the potential of untreated samples was dropped sharply to very low negative values. However, the lower wear volume loss was achieved for Ti6Al4V alloy. SEM images of worn surfaces demonstrated the local detachment of oxide layer within the wear track of MAO/Ti sample. Conversely, no delamination was detected in MAO/Ti6Al4V and a mild abrasive wear was the dominant mechanism.

A Review of the Fatigue Properties of Additively Manufactured Ti-6Al-4V

Science.gov (United States)

Cao, Fei; Zhang, Tiantian; Ryder, Matthew A.; Lados, Diana A.

2018-03-01

Various additive manufacturing (AM) technologies have been used to fabricate Ti-6Al-4V. The fatigue performance of Ti-6Al-4V varies from process to process. In this review, fatigue properties of Ti-6Al-4V alloys made by different AM technologies and post-fabrication treatments were compiled and discussed to correlate with the materials' characteristic features, primarily surface roughness and porosity. Microstructure anisotropy and porosity effects on fatigue crack growth and fatigue life are also presented and discussed. A modified Kitagawa-Takahashi diagram developed from current available fatigue data was used to quantify the influence of defects on fatigue strength. This review aims to assist in selecting/optimizing AM processes to achieve high fatigue resistance in Ti-6Al-4V, as well as provide a better understanding of the advantages and limitations of current AM techniques in producing titanium alloys.

Microstructure of Ti-6Al-4V produced by selective laser melting

International Nuclear Information System (INIS)

Simonelli, M; Tse, Y Y; Tuck, C

2012-01-01

Ti-6Al-4V is the most widely used titanium alloy. Manufacturing of Ti-6Al-4V components using novel additive processing techniques such as selective laser melting is of great interest. This study focuses on the microstructure characterisation of Ti-6Al-4V components produced by selective laser melting (SLM) with full (Ti-6Al-4V base plate) and partial (Ti-6Al-4V needle-shaped bed) support. The starting material, a plasma atomised powder, and the component products are studied using various microscopy techniques including optical, scanning electron and transmission electron microscopy and electron backscattered diffraction (EBSD). Powder particles are fully dense, possess a spherical shape and are composed of acicular α phase. The as-built material shows oriented acicular martensitic phase with well defined columnar grains. The morphology of martensitic phase and microstructural evolution will be discussed in relation to the SLM processing parameters employed and the different cooling rates experienced by the components.

Characterization of laser deposited Ti6Al4V/TiC composite powders on a Ti6Al4V substrate

CSIR Research Space (South Africa)

Mahamood, RM

2014-01-01

Full Text Available This paper reports the material characterization of Ti6Al4V/TiC composite produced by laser metal deposition. The Ti6Al4V/TiC composites were deposited with a composition ratio of 50 wt.% Ti64l4V and 50 wt.% TiC. The depositions were achieved...

Elevated temperature characterization of electron beam freeform fabricated Ti-6Al-4V and dispersion strengthened Ti-8Al-1Er

Energy Technology Data Exchange (ETDEWEB)

Bush, R.W., E-mail: ralph.bush@usafa.edu [Department of Engineering Mechanics, 2354 Fairchild Dr., U.S. Air Force Academy, USAF Academy, CO 80840 (United States); Brice, C.A. [Lockheed Martin Aeronautics Co., Fort Worth, TX (United States)

2012-09-30

Highlights: Black-Right-Pointing-Pointer Electron beam freeform fabrication process. Black-Right-Pointing-Pointer Ti-6Al-4V and rare-earth dispersion Ti alloy. Black-Right-Pointing-Pointer Tensile, creep, and oxidation properties comparable to alloys made with conventional fabrication methods. Black-Right-Pointing-Pointer Fabrication process allows use of rare-earth dispersion Ti alloy. - Abstract: Electron beam freeform fabrication is an additive manufacturing process that can be used to build fully dense, structural metallic parts directly from a three-dimensional computer model. This technique can replace conventional fabrication methods, such as forging or machining from plate, and enable significant cost, time, and tool savings. Additionally, this method enables the fabrication of alloys with novel compositions that are not well suited to production via ingot metallurgy processes. Ti-8Al-1Er is an experimental dispersion strengthened titanium alloy composition that requires rapid cooling to achieve optimal properties and thus is not amenable to ingot metallurgy production methods. Oxide dispersion strengthened alloys, such as Ti-8Al-1Er are known to have excellent thermal stability and improved high temperature properties. In this work, the room temperature tensile, elevated temperature tensile, creep properties and oxidation resistance of electron beam additive manufactured Ti-6Al-4V and Ti-8Al-1Er were measured and compared to those of laser beam additive manufactured Ti-8Al-1Er and wrought Ti-6Al-4V. Elevated temperature tensile properties were measured between 93 Degree-Sign and 538 Degree-Sign C. Creep tests were performed between 425 Degree-Sign and 455 Degree-Sign C at stresses between 345 and 483 MPa. It was found that the elevated temperature properties of the electron beam additive manufactured products are comparable to those of wrought forms. The elevated temperature strengths of Ti-8Al-1Er are comparable to those of Ti-6Al-4V in percentage of room

An Analysis on the Constitutive Models for Forging of Ti6Al4V Alloy Considering the Softening Behavior

Science.gov (United States)

Souza, Paul M.; Beladi, Hossein; Singh, Rajkumar P.; Hodgson, Peter D.; Rolfe, Bernard

2018-05-01

This paper developed high-temperature deformation constitutive models for a Ti6Al4V alloy using an empirical-based Arrhenius equation and an enhanced version of the authors' physical-based EM + Avrami equations. The initial microstructure was a partially equiaxed α + β grain structure. A wide range of experimental data was obtained from hot compression of the Ti6Al4 V alloy at deformation temperatures ranging from 720 to 970 °C, and at strain rates varying from 0.01 to 10 s-1. The friction- and adiabatic-corrected flow curves were used to identify the parameter values of the constitutive models. Both models provided good overall accuracy of the flow stress. The generalized modified Arrhenius model was better at predicting the flow stress at lower strain rates. However, the model was inaccurate in predicting the peak strain. In contrast, the enhanced physical-based EM + Avrami model revealed very good accuracy at intermediate and high strain rates, but it was also better at predicting the peak strain. Blind sample tests revealed that the EM + Avrami maintained good predictions on new (unseen) data. Thus, the enhanced EM + Avrami model may be preferred over the Arrhenius model to predict the flow behavior of Ti6Al4V alloy during industrial forgings, when the initial microstructure is partially equiaxed.

Growth of aluminum-free porous oxide layers on titanium and its alloys Ti-6Al-4V and Ti-6Al-7Nb by micro-arc oxidation.

Science.gov (United States)

Duarte, Laís T; Bolfarini, Claudemiro; Biaggio, Sonia R; Rocha-Filho, Romeu C; Nascente, Pedro A P

2014-08-01

The growth of oxides on the surfaces of pure Ti and two of its ternary alloys, Ti-6Al-4V and Ti-6Al-7Nb, by micro-arc oxidation (MAO) in a pH 5 phosphate buffer was investigated. The primary aim was to form thick, porous, and aluminum-free oxide layers, because these characteristics favor bonding between bone and metal when the latter is implanted in the human body. On Ti, Ti-6Al-4 V, and Ti-6Al-7Nb, the oxides exhibited breakdown potentials of about 200 V, 130 V, and 140 V, respectively, indicating that the oxide formed on the pure metal is the most stable. The use of the MAO procedure led to the formation of highly porous oxides, with a uniform distribution of pores; the pores varied in size, depending on the anodizing applied voltage and time. Irrespective of the material being anodized, Raman analyses allowed us to determine that the oxide films consisted mainly of the anatase phase of TiO2, and XPS results indicated that this oxide is free of Al and any other alloying element. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of Ti/Cr content on the microstructures and hydrogen storage properties of Laves phase-related body-centered-cubic solid solution alloys

Energy Technology Data Exchange (ETDEWEB)

Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering and Materials Science, Wayne State University, MI 48202 (United States); Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States)

2015-02-15

Highlights: • Influences of Ti/Cr to BCC to hydrogen storage properties were reported. • A new activation using hydrogen pressure at 5 MPa was developed. • A discharge capacity of 463 mA h g{sup −1} was reported on a C14(36%)/BCC(64%) alloy. • Increase in Ti/Cr increases storage capacity and decreases high-rate performance. • The high-rate performance was dominated by the surface reaction. - Abstract: A series of BCC/C14 mixed phase alloys with the chemical composition of Ti{sub 13.6+x}Zr{sub 2.1}V{sub 44}Cr{sub 13.2−x}Mn{sub 6.9}Fe{sub 2.7}Co{sub 1.4}Ni{sub 15.7}Al{sub 0.3}, x = 0, 2, 4, 6, 8, 10, and 12, was fabricated, and their structural, gaseous phase and electrochemical hydrogen storage properties were studied. Raising the maximum pressure for measuring the gaseous hydrogen storage capacity allowed these alloys to reach full activation, and the maximum discharge capacities ranged from 375 to 463 mA h g{sup −1}. As the Ti/Cr ratio in the alloy composition increased, the maximum gaseous hydrogen storage capacity improved due to the expansion in both BCC and C14 unit cells. However, reversibility decreased due to the higher stability of the hydride phase, as indicated by the lower equilibrium pressures measured for these alloys. As with most other metal hydride alloys, the electrochemical capacities measured at 50 and 4 mA g{sup −1} fell between the boundaries set by the maximum and reversible gaseous hydrogen storage capacities. The poorer high-rate dischargeability observed with higher Ti/Cr ratios was attributed to the lower surface exchange current (less catalytic). Two other negative impacts observed with higher Ti/Cr ratios in the alloy composition are poorer cycle stability and lower open-circuit voltage.

Improvement of corrosion resistance of vanadium alloys in high-temperature pressurized water

International Nuclear Information System (INIS)

Fujiwara, Mitsuhiro; Sakamoto, Toshiya; Satou, Manabu; Hasegawa, Akira; Abe, Katsunori; Kaiuchi, Kazuo; Furuya, Takemi

2005-01-01

Corrosion tests in pressurized and vaporized water were conducted for V-based high Cr and Ti alloys and V-4Cr-4Ti type alloys containing minor elements such as Si, Al and Y. Weight losses were observed for every alloy after corrosion tests in pressurized water. It was apparent that addition of Cr effectively reduced the weight change in pressurized water. The weight loss of V-4Cr-4Ti type alloys in corrosion tests in vaporized water was also reduced as Cr content increased. The V-20Cr-4Ti alloy had a slight weight gain, almost same as that of SUS316, which had the best corrosion properties in the tested alloys. The elongation of alloys with in excess of 10% Cr was reduced as Cr content increased. The elongations of the V-12Cr-4Ti and the V-15Cr-4Ti alloys were significantly reduced by corrosion and cleavage fracture was observed reflecting hydrogen embrittlement. The reduced elongations of the alloys of the alloys were recovered to the same level of as annealed conditions after hydrogen degassing. After corrosion, the V-15Cr-4Ti-0.5Y alloy still kept enough elongation, suggesting that the addition of Y is effective to reduce the hydrogen embrittlement. (author)

An evaluation of the susceptibility of V-4Cr-4Ti to stress corrosion cracking in room temperature DIII-D water

Energy Technology Data Exchange (ETDEWEB)

Kurtz, R.J.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Johnson, W.R.

1997-04-01

Two fatigue precracked compact tension (CT) specimens of V-4Cr-4Ti were statically loaded to a stress intensity factor of about 30 MPa{radical}m in room temperature DIII-D water. The first specimen was tested for a period of about 30 days and the second specimen for about 54 days. At the conclusion of each test the specimens were fractured, and the fracture surfaces examined with a scanning electron microscope (SEM) to determine if SCC had occurred. No SCC was found in either test specimen.

Study of the impact of treatment modes on hardness, deformability and microstructure of VT6 (Ti-6Al-4V and VV751P (Ni-15Co-10Cr alloy samples after selective laser sintering

Directory of Open Access Journals (Sweden)

Galkina Natalia V.

2017-01-01

Full Text Available Selective laser sintering is an advanced method for obtaining sophisticated products and assembly permanent joints. This is particularly relevant for heat resistant alloys employed in aviation equipment. Heat treatment modes traditionally applied to the products are chosen in accordance with conditions of further product operation. In this paper there are given the results of experimental study of hardness, deformability and microstructure of samples after selective laser sintering of Ni-15Co-10Cr and Ti–6Al–4V alloy powders. It has been determined that Ni-15Co-10Cr alloy ageing increases the hardness and deformability of samples; these characteristics decrease if the ageing lasts for 9-19 hours. Annealing of Ti–6Al–4V alloy samples results in preserving original hardness. After complete annealing, the hardness of samples decreases from 32 … 33HRC to 24 … 26HRC. Microstructural studies showed that there are cracks between layers in the surface of Ti–6Al–4V alloy samples after sintering and not complete annealing. After full annealing, cracks' width and length decreased. Cracks in Ni-15Co-10Cr alloy samples' microstructure were not detected.

Surface modification of Ti-_6Al-_4V titanium alloy by combined ion-plasma treatment

International Nuclear Information System (INIS)

Cherenda, N.N.; Shimanskij, V.I.; Laskovnev, A.P.; Basalaj, A.V.; Astashinskij, V.M.; Kuz'mitskij, A.M.

2015-01-01

Investigation results of phase and elemental composition, microhardness and friction coefficient of Ti-_6Al-_4V alloy samples precoated by titanium subjected to compression plasma flows treatment have been presented in this work. It has been established that the combined effect of ion-plasma flows diminishes aluminum and vanadium concentration in the surface layer, leads to the growth of its microhardness and decrease of the friction coefficient. (authors)

The Tribological Performance of Surface Treated Ti6A14V as Sliding Against Si3N4 Ball and 316L Stainless Steel Cylinder

Science.gov (United States)

Kao, W. H.; Su, Y. L.; Horng, J. H.; Huang, H. C.

2016-12-01

Closed field unbalanced magnetron sputtering was used to deposit diamond-like carbon (Ti-C:H) coatings on Ti6Al4V alloy and gas nitrided Ti6Al4V alloy. Four different specimens were prepared, namely untreated Ti6Al4V alloy (Ti6Al4V), gas nitrided Ti6Al4V alloy (N-Ti6Al4V), Ti-C:H-coated Ti6Al4V alloy (Ti-C:H/Ti6Al4V) and Ti-C:H-coated gas nitrided Ti6Al4V alloy (Ti-C:H/N-Ti6Al4V). The tribological properties of the four specimens were evaluated using a reciprocating wear tester sliding against a Si3N4 ball (point contact mode) and 316L stainless steel cylinder (line contact mode). The wear tests were performed in a 0.89 wt.% NaCl solution. The results showed that the nitriding treatment increased the surface roughness and hardness of the Ti6Al4V alloy and improved the wear resistance as a result. In addition, the Ti-C:H coating also improved the tribological performance of Ti6Al4V. For example, compared to the untreated Ti6Al4V sample, the Ti-C:H coating reduced the wear depth and friction coefficient by 340 times and 10 times, respectively, in the point contact wear mode, and 151 times and 9 times, respectively, in the line contact wear mode. It is thus inferred that diamond-like carbon coatings are of significant benefit in extending the service life of artificial biomedical implants.

Effect of plasma molybdenized buffer layer on adhesive properties of TiN film coated on Ti6Al4V alloy

Energy Technology Data Exchange (ETDEWEB)

Qin, Lin, E-mail: qinlin@tyut.edu.cn; Yi, Hong; Kong, Fanyou; Ma, Hua; Guo, Lili; Tian, Linhai; Tang, Bin

2017-05-01

Highlights: • A molybdenized layer was prepared as a buffer layer under TiN film on Ti6Al4V. • The molybdenized layer can enhance adhesion strength of PVD coatings effectively. • The duplex treated samples increase elastic energy ratio in the impact tests. • The enhancement attributes to the hardness improvement and inverted-S shape elastic modulus profile of the modified layer. - Abstract: Effect of molybdenized buffer layer on adhesion strength of TiN film on Ti6Al4V alloy was investigated. The buffer layer composed of a dense molybdenum deposition layer, a rapid drop zone and a slow fall zone was prepared using double glow plasma surface alloying technique. Scratch tests and low energy repeated impact tests were adopted to comparatively evaluate the duplex treated layers and the single TiN samples. The results show that the critical load was increased from 62 N for the single TiN film to over 100 N for the duplex treated layer. The volume of impact pit, formed in impact tests, of the single TiN samples is 9.15 × 10{sup 6} μm{sup 3}, and about 1.5 times than that of the duplex treated samples. The Leeb hardness values reveal that about 70% impact energy was transferred to the single TiN samples to generate permanent deformation, while that was only about 47% for the duplex treated samples. The mechanism of improving adhesion strength is attributed to synergistic effect due to an inverted-S shape elastic modulus distribution produced by the molybdenized layer.

The shock Hugoniot of the intermetallic alloy Ti-46.5Al-2Nb-2Cr

International Nuclear Information System (INIS)

Millett, Jeremy; Gray, George T. Rusty III; Bourne, Neil

2000-01-01

Plate impact experiments were conducted on a γ-titanium aluminide (TiAl) based ordered intermetallic alloy. Stress measurements were recorded using manganin stress gauges supported on the back of TiAl targets using polymethylmethacrylate windows. The Hugoniot in stress-particle velocity space for this TiAl alloy was deduced using impedance matching techniques. The results in this study are compared to the known Hugoniot data of the common alpha-beta engineering Ti-based alloy Ti-6Al-4V. The results of the current study on the intermetallic alloy TiAl support that TiAl possesses a significantly higher stress for a given particle velocity than the two-phase Ti-6Al-4V alloy. (c) 2000 American Institute of Physics

Microstructure, microhardness and corrosion resistance of remelted TiG2 and Ti6Al4V by a high power diode laser

International Nuclear Information System (INIS)

Amaya-Vazquez, M.R.; Sánchez-Amaya, J.M.; Boukha, Z.; Botana, F.J.

2012-01-01

Highlights: ► Laser remelting of TiG2 and Ti6Al4V is performed with argon shielded diode laser. ► Microstructure, microhardness and corrosion of remelted samples are deeply analysed. ► Microstructural changes of laser remelted TiG2 lead to microhardness increase. ► Remelted Ti6Al4V presents microhardness increase and corrosion improvement. ► Martensite depth in remelted Ti6Al4V is linearly proportional to laser fluence. - Abstract: The high strength, low density and superior corrosion resistance allow titanium alloys to be widely employed in different industrial applications. The properties of these alloys can be modulated by different heat treatments, including laser processing. In the present paper, laser remelting treatments, performed with a high power diode laser, were applied to samples of two titanium alloys (TiG2 and Ti6Al4V). The influence of the applied laser fluence on microstructure, microhardness and corrosion resistance is investigated. Results show that laser remelting treatments with appropriate fluences provoke microstructural changes leading to microhardness increase and corrosion resistance improvement.

Effect of composition on the structure and properties of Ti-Co-Cr alloys

Directory of Open Access Journals (Sweden)

T. Matković

2010-01-01

Full Text Available The present work is a study of six as-cast Ti-Co-Cr alloys in the Ti-rich region with the purpose of examining the possibility of obtaining a new β-type Ti-alloys. Two experimental alloys Ti80Co10Cr10 and Ti70Co10Cr20 are nearly single-phases and are identified as bcc β-Ti phase. They also display the lowest hardness values and the best corrosion properties. The present study indicates that the region of biomedically-acceptable ternary Ti-rich alloys is situated within lower concentrations of alloying elements, i.e. about 10 at.% Co and 20 at. % Cr.

In vitro assessments on bacterial adhesion and corrosion performance of TiN coating on Ti6Al4V titanium alloy synthesized by multi-arc ion plating

International Nuclear Information System (INIS)

Lin Naiming; Huang Xiaobo; Zhang Xiangyu; Fan Ailan; Qin Lin; Tang Bin

2012-01-01

TiN coating was synthesized on Ti6Al4V titanium alloy surface by multi-arc ion plating (MIP) technique. Surface morphology, cross sectional microstructure, elemental distributions and phase compositions of the obtained coating were analyzed by means of scanning electron microscope (SEM), optical microscope (OM), glow discharge optical emission spectroscope (GDOES) and X-ray diffraction (XRD). Bacterial adhesion and corrosion performance of Ti6Al4V and the TiN coating were assessed via in vitro bacterial adhesion tests and corrosion experiments, respectively. The results indicated that continuous and compact coating which was built up by pure TiN with a typical columnar crystal structure has reached a thickness of 1.5 μm. This TiN coating could significantly reduce the bacterial adhesion and enhance the corrosion resistance of Ti6Al4V substrate.

Propriedades mecânicas e resistência à corrosão da liga Ti-4Al-4V obtida da reciclagem da liga Ti-6Al-4V

Directory of Open Access Journals (Sweden)

Jesuíno G.A.

2001-01-01

Full Text Available The present work aimed to study the transformation from as-cast structure of the Ti4Al-4V alloy, as a result of the Ti-6Al-4V recycling, after some rapid heat treatments based on martensitic reactions. The effects on mechanical properties were evaluated by Vickers hardness measurements, Charpy and monotonic tensile tests. The corrosion strength was tested by immersion during 4 months in artificial physiological solutions, to evaluate its possible use as a biomaterial. The data pointed to: a a reduction on corrosion strength for quenching above beta transus; b significant increasing on hardness and mechanical strength; c a maintenance of impact toughness; d the corrosion strength for immersion in a NaCl 1%+ NaF 0,1% (m/m was lower in all conditions, specially for those including heating to 900 °C.

Recovery characteristics of neutron-irradiated V-Ti alloys

International Nuclear Information System (INIS)

Leguey, T.; Pareja, R.

2000-01-01

The recovery characteristics of neutron-irradiated pure V and V-Ti alloys with 1.0 and 4.5 at.% Ti have been investigated by positron annihilation spectroscopy. Microvoid formation during irradiation at 320 K is produced in pure V and V-1Ti but not in V-4.5Ti. The results are consistent with a model of swelling inhibition induced by vacancy trapping by solute Ti during irradiation. The temperature dependencies of the parameter S in the range 8-300 K indicate a large dislocation bias for vacancies and solute Ti. This dislocation bias prevents the microvoid nucleation in V-4.5Ti, and the microvoid growth in V-1Ti, when vacancies become mobile during post-irradiation annealing treatments. A characteristic increase of the positron lifetime is found during recovery induced by isochronal annealing. It is attributed to a vacancy accumulation into the lattice of Ti oxides precipitated during cooling down, or at their matrix/precipitate interfaces. These precipitates could be produced by the decomposition of metastable phases of Ti oxides formed during post-irradiation annealing above 1000 K

Effect of CeO2 on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding

OpenAIRE

Chen, Tao; Liu, Defu; Wu, Fan; Wang, Haojun

2017-01-01

To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO2 powders as the basic pre-placed materials. A certain amount of CeO2 powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO2 additive on the ph...

Acoustic tests of elastic and microplastic properties of V-Ti-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Chernov, V.M. [Fiziko-Ehnergeticheskij Institut, Obninsk (Russian Federation); Rezvoushkin, A.V. [Fiziko-Ehnergeticheskij Institut, Obninsk (Russian Federation); Kardashev, B.K. [Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation)

1996-10-01

The non-linear acoustic properties of V-10Ti-5Cr alloy before and after proton irradiation (dose 2.2 x 10{sup 14} p/cm{sup 2}) were investigated using a composite oscillator technique at longitudinal vibration frequencies of about 100 kHz. Acoustic parameters (decrement and resonance frequency) of the samples demonstrated noticeable amplitude dependencies of hysteretic type both in undeformed and deformed states. An unusual influence of plastical pre-straining on irradiated sample was found which resulted in small decreases in damping and increases in resonance frequency, and hence, of the elastic modulus. Damping in an irradiated sample was higher and its resonant frequency was lower as compared with a non-irradiated sample. This acoustic effect correlated with the results of microhardness and yield strength measurements. The experimental results are discussed in the framework of a model which predicts the creation by proton irradiation of defects which aid the motion of dislocations in V-alloys. (orig.).

The effects of low fugacity hydrogen in duplex- and beta-annealed Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Tal-Gutelmacher, E.; Eliezer, D.; Eylon, D.

2004-01-01

Due to its excellent combination of a high strength/weight ratio and good corrosion behavior, Ti-6Al-4V alloys are ranked among the most important advanced materials for a variety of aerospace, chemical engineering, biomaterials, marine and commercial applications. However, in many of these technological applications, this alloy is exposed to environments which can act as sources of hydrogen, and severe problems may arise based on its susceptibility to hydrogen embrittlement. Even small hydrogen concentrations might lead to failure. Consequently, a comprehensive knowledge of hydrogen-trapping interactions is necessary to better understand the trapping mechanisms, the types of the trap sites, the trapped hydrogen content, in order to determine the safe service conditions of this alloy in the aerospace industry. The objective of this paper is to investigate the role of microstructure on hydrogen absorption/desorption behavior in Ti-6Al-4V alloy, with specific emphasis on the nature of the interaction between microstructural traps and hydrogen atoms. The effect of low fugacity hydrogen on the microstructure is studied using X-ray diffraction (XRD), and electron microscopy (SEM and TEM), while the absorption and desorption characteristics are determined by means of a hydrogen determinator and thermal desorption spectroscopy (TDS), respectively. The role of microstructure on hydrogen absorption and desorption behavior is discussed in detail

Effect of helium on swelling and microstructural evolution in ion-irradiated V-15Cr-5Ti alloy

International Nuclear Information System (INIS)

Loomis, B.A.; Kestel, B.J.; Gerber, S.B.; Ayrault, G.

1986-03-01

An investigation was made on the effects of implanted helium on the swelling and microstructural evolution that results from energetic single- and dual-ion irradiation of the V-15Cr-5Ti alloy. Single-ion irradiations were utilized for a simulated production of the irradiation damage that might be expected from neutron irradiation of the alloy in a reactor with a fast neutron energy spectrum (E > 0.1 MeV). Dual-ion irradiations were utilized for a simulated production of the simultaneous creation of helium atoms and irradiation damage in the alloy in the MFR environment. Experimental results are also presented on the radiation-induced segregation of the constituent atoms in the single- and dual-ion irradiated alloy

Excessive Anteversion Leads to Failure at 3 Years Due to Impingement as Evidenced by Twin Notches in Ti6A4V Stem

Directory of Open Access Journals (Sweden)

Thomas Donaldson

2015-08-01

Full Text Available A 63-year old female with bilateral hip replacements was referred to our clinic for pain and elevated metal ions. Her left hip had been revised earlier. The right hip had an SROM Ti6Al4V stem implanted with a 28mm head, a 28mm CoCr liner and Pinnacle Ti6Al4V shell. The patient reported pain, numbness, tingling, and repeated clicking and popping sensations with gait. She specifically noted that her hip would freeze while walking and could pop rising from a chair. Repeated metal ion levels showed Co (blood17ppb, Cr (serum 21ppb, and Ti (blood at 69ppb. CT-images of right hip revealed femoral stem anteversion was 43° and cup anteversion was 40°, for a combined anteversion of 83°. The right hip was revised 3.5 years postoperatively for persistent pain and elevated metal ions. At surgery, large twin notches were evident on her posterior femoral neck and 10mm-wide scalloped damage was evident in the rim of the Ti6A4V shell. SEM-imaging revealed contaminating layers on CoCr head containing elements Al, V and Ti. These indicated that titanium-alloy particles liberated by cup-to-neck impingements had transferred to the CoCr bearings. Our intent in this case was not to document that a MOM bearing produced impingement damage, because this case clearly implicated adverse surgical positioning. Rather, the intent was to document sequelae likely in a THA case that has a metal cup impinging on a metal femoral neck. In particular, twin notches on the femoral neck indicated that this patient was routinely impinging her Ti6Al4V shell against the Ti6Al4V neck and also subluxing her femoral head out of the cup. These signs are a clear indication that one or both components must be revised, as opposed to simply replacing the CoCr liner with a revision polyethylene liner.

Multifunctional Beta Ti Alloy with Improved Specific Strength

Science.gov (United States)

Park, Chan Hee; Hong, Jae-Keun; Lee, Sang Won; Yeom, Jong-Taek

2017-12-01

Gum metals feature properties such as ultrahigh strength, ultralow elastic modulus, superelasticity, and superplasticity. They are composed of elements from Groups 4 and 5 of the periodic table and exist when the valance electron concentration (\\overline{e/a}) is 4.24; the bond order (\\overline{Bo}) is 2.87; and the "d" electron-orbital energy level (\\overline{Md}) is 2.45 eV. Typical compositions include Ti-23Nb-2Zr-0.7Ta-O and Ti-12Ta-9Nb-6Zr-3 V-O, which contain large amounts of heavy Group-5 elements such as Nb and Ta. In the present study, to improve the specific strength of a multifunctional beta Ti alloy, three alloys (Ti-20Nb-5Zr-1Fe-O, Ti-12Zr-10Mo-4Nb-O, and Ti-24Zr-9Cr-3Mo-O) were designed by satisfying the above three requirements while adding Fe, Mo, and Cr, which are not only lightweight but also have strong hardening effects. Microstructural and mechanical property analyses revealed that Ti-20Nb-5Zr-1Fe-O has a 25% higher specific strength than gum metal while maintaining an ultralow elastic modulus.

In vitro evaluation of cytotoxicity and corrosion behavior of commercially pure titanium and Ti-6Al-4V alloy for dental implants.

Science.gov (United States)

Chandar, Sanchitha; Kotian, Ravindra; Madhyastha, Prashanthi; Kabekkodu, Shama Prasada; Rao, Padmalatha

2017-01-01

The aim of this study was to investigate the cytotoxicity in human gingival fibroblast by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and corrosion behavior by potentiodynamic polarization technique of commercially pure titanium (Ti 12) and its alloy Ti-6Al-4V (Ti 31). In the present in vitro study, cytotoxicity of Ti 12 and Ti 31 in human gingival fibroblast by MTT assay and the corrosion behavior by potentiodynamic polarization technique in aqueous solutions of 0.1 N NaCl, 0.1 N KCl, and artificial saliva with and without NaF were studied. The independent t -test within materials and paired t-test with time interval showed higher cell viability for Ti 12 compared to Ti 31. Over a period, cell viability found to stabilize in both Ti 12 and Ti 31. The effects of ions of Ti and alloying elements aluminum and vanadium on the cell viability were found with incubation period of cells on samples to 72 h. The electrochemical behavior of Ti 12 and Ti 31 in different experimental solutions showed a general tendency for the immersion potential to shift steadily toward nobler values indicated formation of TiO 2 and additional metal oxides. The multiphase alloy Ti-6Al-4V showed more surface pitting. The commercially pure Ti showed better cell viability compared to Ti 31. Less cell viability in Ti 31 is because of the presence of aluminum and vanadium. A significant decrease in cytotoxicity due to the formation of TiO 2 over a period of time was observed both in Ti 12 and Ti 31. The electrochemical behavior of Ti 12 and Ti 31 in different experimental solutions showed a general tendency for the immersion potential to shift steadily toward nobler values indicated formation of TiO2 and additional metal oxides. Ti 31 alloy showed surface pitting because of its multiphase structure.

Evolution of the electronic structure and physical properties of Fe2MeAl (Me = Ti, V, Cr) Heusler alloys

International Nuclear Information System (INIS)

Shreder, E; Streltsov, S V; Svyazhin, A; Makhnev, A; Marchenkov, V V; Lukoyanov, A; Weber, H W

2008-01-01

We present the results of experiments on the optical, electrical and magnetic properties and electronic structure and optical spectrum calculations of the Heusler alloys Fe 2 TiAl, Fe 2 VAl and Fe 2 CrAl. We find that the drastic transformation of the band spectrum, especially near the Fermi level, when replacing the Me element (Me = Ti, V, Cr), is accompanied by a significant change in the electrical and optical properties. The electrical and optical properties of Fe 2 TiAl are typical for metals. The abnormal behavior of the electrical resistivity and the optical properties in the infrared range for Fe 2 VAl and Fe 2 CrAl are determined by electronic states at the Fermi level. Both the optical spectroscopic measurements and the theoretical calculations demonstrate the presence of low-energy gaps in the band spectrum of the Heusler alloys. In addition, we demonstrate that the formation of Fe clusters may be responsible for the large enhancement of the total magnetic moment in Fe 2 CrAl

A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate

International Nuclear Information System (INIS)

Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

2013-01-01

This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, Ti6Al4V titanium alloy plates with a thickness of 0.8 mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.

Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy

Energy Technology Data Exchange (ETDEWEB)

Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl

2017-01-01

Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1 min) caused decrease in the surface hydrophilic character, while longer time (10 min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. - Highlights: • Surface of five Ti-6Al-4V alloy samples were smoothed and polished successively. • The

Role of microstructure in the mean stress dependence of fatigue strength in Ti-6Al-4V alloy

Energy Technology Data Exchange (ETDEWEB)

Ivanova, S.G.; Cohen, F.S.; Biederman, R.R.; Sisson, R.D. Jr.

1999-07-01

The high cycle fatigue properties of Ti-6Al-4V alloy with six different microstructure/texture combinations were investigated. Only materials with lamellar and fine bimodal microstructures exhibited linear Goodman relationship on the constant fatigue life diagram. Materials with coarse bimodal and equiaxed microstructures had anomalous mean stress dependency, with HCF strength at intermediate mean stresses being significantly lower than predicted by Goodman relationship, regardless of whether material was forged or cross-rolled. The role of microstructure in mean stress sensitivity behavior of Ti-6Al-4V is studied. Cyclic strain tests were conducted for all microstructures, and the results of strain-controlled and stress-controlled cyclic tests are compared and discussed.

Mechanical properties of mill-annealed Ti6Al4V investment cast

CSIR Research Space (South Africa)

Mutombo, K

2011-07-01

Full Text Available Ti6Al4V alloy, produced by investment casting using yttria stabilized zirconia, was machined and then mill-annealed in vacuum furnace. The ultimate strength, yield strength and percentage elongation were largely improved compared to the same alloy...

Improving the osteointegration of Ti6Al4V by zeolite MFI coating

Energy Technology Data Exchange (ETDEWEB)

Li, Yong [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China); Jiao, Yilai [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning 110016 (China); Li, Xiaokang [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China); Guo, Zheng, E-mail: guozheng@fmmu.edu.cn [Department of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi' an, Shaanxi 710032 (China)

2015-05-01

Osteointegration is crucial for success in orthopedic implantation. In recent decades, there have been numerous studies aiming to modify titanium alloys, which are the most widely used materials in orthopedics. Zeolites are solid aluminosilicates whose application in the biomedical field has recently been explored. To this end, MFI zeolites have been developed as titanium alloy coatings and tested in vitro. Nevertheless, the effect of the MFI coating of biomaterials in vivo has not yet been addressed. The aim of the present work is to evaluate the effects of MFI-coated Ti6Al4V implants in vitro and in vivo. After surface modification, the surface was investigated using field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). No difference was observed regarding the proliferation of MC3T3-E1 cells on the Ti6Al4V (Ti) and MFI-coated Ti6Al4V (M−Ti) (p > 0.05). However, the attachment of MC3T3-E1 cells was found to be better in the M−Ti group. Additionally, ALP staining and activity assays and quantitative real-time RT-PCR indicated that MC3T3-E1 cells grown on the M−Ti displayed high levels of osteogenic differentiation markers. Moreover, Van-Gieson staining of histological sections demonstrated that the MFI coating on Ti6Al4V scaffolds significantly enhanced osteointegration and promoted bone regeneration after implantation in rabbit femoral condylar defects at 4 and 12 weeks. Therefore, this study provides a method for modifying Ti6Al4V to achieve improved osteointegration and osteogenesis. - Highlights: • Osteointegration is a crucial factor for orthopedic implants. • We coated MFI zeolite on Ti6Al4V substrates and investigated the effects in vitro and in vivo. • The MFI coating displayed good biocompatibility and promoted osteogenic differentiation in vitro. • The MFI coating promoted osteointegration and osteogenesis peri-implant in vivo.

Atomic investigation of alloying Cr, Ti, Y additions in a grain boundary of vanadium

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengbo, E-mail: zhangpb@dlmu.edu.cn [Department of Physics, Dalian Maritime University, Dalian 116026 (China); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Li, Xiaojie; Zhao, Jijun [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024 (China); Zheng, Pengfei; Chen, Jiming [Southwestern Institute of Physics, Chengdu 610041 (China)

2016-01-15

The effect of alloying additions (Cr, Ti and Y) in a vanadium (V) ∑3 (111) grain boundary (GB) is investigated by first-principles calculations. To determine site preference and segregation properties of Cr, Ti and Y in the GB and bulk, we calculate the formation energies and segregation energies for different interstitial and substitutional sites. Cr/Ti/Y atom prefers to segregate to the substitutional sites of the GB from bulk environment, whereas Cr segregation to GB is very weak. Based on the Rice and Wang's model, Cr acts as the GB cohesion, while Ti and Y are strong embrittlers. The analysis of atomic and electronic structures provides a reasonable expansion for the embrittlement behavior. Moreover, the effect of Cr, Ti and Y in the GB on solution of interstitial impurities C, N, O, H, and He are determined. The results show that Cr restrains solution of these impurities in the GB, while Ti tends to form Ti–N complex by absorbing N impurities and Y can absorbs O and He impurities. The present calculations are helpful for understanding the behavior of alloying Cr, Ti, Y additions at the grain boundary of vanadium.

Synthesis and Characterization of Hydroxyapatite-Collagen-Chitosan (HA/Col/Chi) Composite Coated on Ti6Al4V

Science.gov (United States)

Charlena; Bikharudin, Ahmad; Wahyudi, Setyanto Tri

2018-01-01

HA-collagen-chitosan (HA/col/chi) composite is developed to increase bioactivity adhesiveness between the metal and the material composite and to improve corrosion resistance. The Ti6Al4V alloy was coated by soaking in HA/col/chi composite at room temperature and then allowed to stand for 5, 6, and 7 days. Diffraction pattern analysis of the coated Ti6Al4V alloy showed that the dominant phase were HA and Ti6Al4V alloy. Corrosion resistance test in media by using 0.9% NaCl showed the corrosion rate at the level of 0.3567 mpy, which was better than that of the uncoated Ti6Al4V alloy (0.4152 mpy). In vitro cytocompatibility assay on endothelial cell of calf pulmonary artery endothelium (CPAE) (ATCC-CCL 209) showed there was no toxicity in the cell culture with the percent inhibition of 33.33% after 72 hours of incubation.

Calculation of phase equilibria in Ti-Al-Cr-Mn quaternary system for developing lower cost titanium alloys

International Nuclear Information System (INIS)

Lu, X.G.; Li, C.H.; Chen, L.Y.; Qiu, A.T.; Ding, W.Z.

2011-01-01

Highlights: → This paper is about the concept of designing the lower cost titanium alloy. → The thermodynamic database of Ti-Al-Cr-Mn system is built up by Calphad method. → The pseudobinary sections with Cr: Mn = 3:1 and Al = 3, 4.5 and 6.0 wt% are calculated. → This may provide the theoretical support for designing the lower cost titanium alloy. - Abstract: The Ti-Al-Cr-Mn system is a potentially useful system for lower cost titanium alloy development; however, there are few reports about the experimental phase diagrams and the thermodynamical assessment for this system. In this study, the previous investigations for the thermodynamic descriptions of the sub-systems in the Ti-Al-Cr-Mn system are reviewed, our previous assessment for the related sub-systems in this quaternary system is summarized, the thermodynamical database of this quaternary system is built up by directly extrapolating from all sub-systems assessed by means of the Calphad method, then the pseudobinary sections with Cr:Mn = 3:1 and Al = 0.0, 3.0, 4.5 and 6.0 wt% are calculated, respectively. These pseudobinary phase diagrams may provide the theoretical support for designing the lower cost titanium alloys with different microstructures (α, α + β, and β titanium alloy).

Microstructure/Oxidation/Microhardness Correlations in Gamma-Based and Tau-Based Al-Ti-Cr Alloys

Science.gov (United States)

Brady, Michael P.; Smialek, J. L.; Humphrey, D. L.

1994-01-01

The relationships between alloy microstructure and air oxidation kinetics and alloy microstructure and microhardness in the Al-Ti-Cr system for exposures at 800 C and 1000 C were investigated. The relevant phases were identified as tau (Ll2), gamma (LIO), r-Al2Ti, TiCrAl (laves), and Cr2AI. Protective alumina formation was associated with tau, Al-rich TiCrAl, and gamma/TiCrAl mixtures. Brittleness was associated with the TiCrAl phase and tau decomposition to A12Ti + Cr2AI. It was concluded that two-phase gamma + TiCrAl alloys offer the greatest potential for oxidation resistance and room temperature ductility in the Al-Ti-Cr system.

Microstructure, microhardness and corrosion resistance of remelted TiG2 and Ti6Al4V by a high power diode laser

Energy Technology Data Exchange (ETDEWEB)

Amaya-Vazquez, M.R. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Sanchez-Amaya, J.M., E-mail: josemaria.sanchez@uca.es [Titania, Ensayos y Proyectos Industriales S.L., Ctra Sanlucar A-2001 Km 7,5, Parque Tecnologico TecnoBahia-Edif. RETSE Nave 4, 11500 El Puerto de Santa Maria, Cadiz (Spain); Departamento de Fisica Aplicada, CASEM, Avda. Republica Saharaui s/n, 11510-Puerto Real, Cadiz (Spain); Boukha, Z.; Botana, F.J. [Laboratorio de Corrosion y Proteccion, Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Avda. Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain)

2012-03-15

Highlights: Black-Right-Pointing-Pointer Laser remelting of TiG2 and Ti6Al4V is performed with argon shielded diode laser. Black-Right-Pointing-Pointer Microstructure, microhardness and corrosion of remelted samples are deeply analysed. Black-Right-Pointing-Pointer Microstructural changes of laser remelted TiG2 lead to microhardness increase. Black-Right-Pointing-Pointer Remelted Ti6Al4V presents microhardness increase and corrosion improvement. Black-Right-Pointing-Pointer Martensite depth in remelted Ti6Al4V is linearly proportional to laser fluence. - Abstract: The high strength, low density and superior corrosion resistance allow titanium alloys to be widely employed in different industrial applications. The properties of these alloys can be modulated by different heat treatments, including laser processing. In the present paper, laser remelting treatments, performed with a high power diode laser, were applied to samples of two titanium alloys (TiG2 and Ti6Al4V). The influence of the applied laser fluence on microstructure, microhardness and corrosion resistance is investigated. Results show that laser remelting treatments with appropriate fluences provoke microstructural changes leading to microhardness increase and corrosion resistance improvement.

Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

Science.gov (United States)

Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

2007-01-01

Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications. 2006 Wiley Periodicals, Inc.

Radio-frequency plasma nitriding and nitrogen plasma immersion ion implantation of Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Wang, S.Y.; Chu, P.K.; Tang, B.Y.; Zeng, X.C.; Wang, X.F.; Chen, Y.B.

1997-01-01

Nitrogen ion implantation improves the wear resistance of Ti-6Al-4V alloys by forming a hard TiN superficial passivation layer. However, the thickness of the layer formed by traditional ion implantation is typically 100-200 nm and may not be adequate for many industrial applications. We propose to use radio-frequency (RF) plasma nitriding and nitrogen plasma immersion ion implantation (PIII) to increase the layer thickness. By using a newly designed inductively coupled RF plasma source and applying a series of negative high voltage pulses to the Ti-6Al-4V samples. RF plasma nitriding and nitrogen PIII can be achieved. Our process yields a substantially thicker modified layer exhibiting more superior wear resistance characteristics, as demonstrated by data from micro-hardness testing, pin-on-disc wear testing, scanning electron microscopy (SEM), as well as Auger electron spectroscopy (AES). The performance of our newly developed inductively coupled RF plasma source which is responsible for the success of the experiments is also described. (orig.)

Tensile properties of V-5Cr-5Ti alloy after exposure in air environment

Energy Technology Data Exchange (ETDEWEB)

Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

1997-04-01

Oxidation studies were conducted on V-5Cr-5Ti alloy specimens in an air environment to evaluate the oxygen uptake behavior of the alloy as a function of temperature and exposure time. The oxidation rates, calculated from parabolic kinetic measurements of thermogravimetric testing and confirmed by microscopic analysis of cross sections of exposed specimens, were 5, 17, and 27 {mu}m per year after exposure at 300, 400, and 500{degrees}C, respectively. Uniaxial tensile tests were conducted at room temperature and at 500{degrees}C on preoxidized specimens of the alloy to examine the effects of oxidation and oxygen migration on tensile strength and ductility. Correlations were developed between tensile strength and ductility of the oxidized alloy and microstructural characteristics such as oxide thickness, depth of hardened layer, depth of intergranular fracture zone, and transverse crack length.

A modified parallel constitutive model for elevated temperature flow behavior of Ti-6Al-4V alloy based on multiple regression

Energy Technology Data Exchange (ETDEWEB)

Cai, Jun; Shi, Jiamin; Wang, Kuaishe; Wang, Wen; Wang, Qingjuan; Liu, Yingying [Xi' an Univ. of Architecture and Technology, Xi' an (China). School of Metallurgical Engineering; Li, Fuguo [Northwestern Polytechnical Univ., Xi' an (China). School of Materials Science and Engineering

2017-07-15

Constitutive analysis for hot working of Ti-6Al-4V alloy was carried out by using experimental stress-strain data from isothermal hot compression tests. A new kind of constitutive equation called a modified parallel constitutive model was proposed by considering the independent effects of strain, strain rate and temperature. The predicted flow stress data were compared with the experimental data. Statistical analysis was introduced to verify the validity of the developed constitutive equation. Subsequently, the accuracy of the proposed constitutive equations was evaluated by comparing with other constitutive models. The results showed that the developed modified parallel constitutive model based on multiple regression could predict flow stress of Ti-6Al-4V alloy with good correlation and generalization.

Influence of Annealing on Microstructure and Mechanical Properties of Refractory CoCrMoNbTi0.4 High-Entropy Alloy

Science.gov (United States)

Zhang, Mina; Zhou, Xianglin; Zhu, Wuzhi; Li, Jinghao

2018-04-01

A novel refractory CoCrMoNbTi0.4 high-entropy alloy (HEA) was prepared via vacuum arc melting. After annealing treatment at different temperatures, the microstructure evolution, phase stability, and mechanical properties of the alloy were investigated. The alloy was composed of two primary body-centered cubic structures (BCC1 and BCC2) and a small amount of (Co, Cr)2Nb-type Laves phase under different annealing conditions. The microhardness and compressive strength of the heat-treated alloy was significantly enhanced by the solid-solution strengthening of the BCC phase matrix and newborn Laves phase. Especially, the alloy annealed at 1473 K (1200 °C) achieved the maximum hardness and compressive strength values of 959 ± 2 HV0.5 and 1790 MPa, respectively, owing to the enhanced volume fraction of the dispersed Laves phase. In particular, the HEAs exhibited promising high-temperature mechanical performance, when heated to an elevated temperature of 1473 K (1200 °C), with a compressive fracture strength higher than 580 MPa without fracture at a strain of more than 20 pct. This study suggests that the present refractory HEAs have immense potential for engineering applications as a new class of high-temperature structural materials.

First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

Directory of Open Access Journals (Sweden)

Hui Huang

2016-07-01

Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

Microstructure and wear resistance of laser clad TiC + NiCrBSi composite layers on Ti-6Al-4V alloy%TC4钛合金激光熔覆TiC+M涂层组织和耐磨性能研究

Institute of Scientific and Technical Information of China (English)

孙荣禄; 杨贤金

2006-01-01

用CO2激光在TC4合金表面熔覆TiC+Ti和TiC+NiCrBSi金属陶瓷涂层,分析了熔覆层的微观组织,测试了熔覆层的干滑动磨损性能.结果表明,在TiC+Ti激光熔覆层中,TiC颗粒全部溶解,熔覆层的组织是在β-Ti基体上分布着TiC树枝晶;在TiC+NiCrBSi激光熔覆层中,TiC颗粒部分溶解,熔覆层的组织是在γ-Ni树枝晶和γ-Ni+M23(CB)6共晶的基体上分布着细小的TiC颗粒和TiC树枝晶.TiC+Ti激光熔覆层的显微硬度在500～700HV之间,质量磨损率约为TC4合金的1/3;TiC+NiCrBSi激光熔覆层的显微硬度在900～1100HV之间,质量磨损率约为TC4合金的1/10.

Microstructural influence on low-temperature superplasticity of ultrafine-grained Ti-6Al-4V alloy

International Nuclear Information System (INIS)

Ko, Young Gun; Kim, Woo Gyeom; Lee, Chong Soo; Shin, Dong Hyuk

2005-01-01

Microstructural influence on low-temperature superplastic behavior of ultrafine-grained Ti-6Al-4V alloy fabricated by equal channel angular pressing (ECAP) was investigated. The deformed structures were analyzed with the increment of strain by transmission electron microscopy. Also, a series of tensile tests were carried out on ultrafine-grained (UFG) samples to measure elongation at temperature of 973 K and at strain rates of 10 -4 to 10 -2 s -1 . The results indicated that elongation was significantly increased with increasing ECAP straining from 4 to 8 revealing more high-angle grain boundaries. Deformation mechanisms for UFG structure were analyzed in the context of inelastic deformation theory, which consisted of dislocation glide and grain boundary sliding

Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy

Science.gov (United States)

El Hadad, Amir A.; Peón, Eduardo; García-Galván, Federico R.; Barranco, Violeta; Parra, Juan; Jiménez-Morales, Antonia; Galván, Juan Carlos

2017-01-01

The aim of this work was to prepare hydroxyapatite coatings (HAp) by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs). Thermogravimetric/Differential Thermal Analyses (TG/DTA) and X-ray Diffraction (XRD) have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR) has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM). The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo’s Simulated Body Fluid (SBF) applying Inductively Coupled Plasma (ICP) spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS). The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties. PMID:28772455

Biocompatibility and Corrosion Protection Behaviour of Hydroxyapatite Sol-Gel-Derived Coatings on Ti6Al4V Alloy

Directory of Open Access Journals (Sweden)

Amir A. El Hadad

2017-01-01

Full Text Available The aim of this work was to prepare hydroxyapatite coatings (HAp by a sol-gel method on Ti6Al4V alloy and to study the bioactivity, biocompatibility and corrosion protection behaviour of these coatings in presence of simulated body fluids (SBFs. Thermogravimetric/Differential Thermal Analyses (TG/DTA and X-ray Diffraction (XRD have been applied to obtain information about the phase transformations, mass loss, identification of the phases developed, crystallite size and degree of crystallinity of the obtained HAp powders. Fourier Transformer Infrared Spectroscopy (FTIR has been utilized for studying the functional groups of the prepared structures. The surface morphology of the resulting HAp coatings was studied by Scanning Electron Microscopy (SEM. The bioactivity was evaluated by soaking the HAp-coatings/Ti6Al4V system in Kokubo’s Simulated Body Fluid (SBF applying Inductively Coupled Plasma (ICP spectrometry. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT and Alamar blue cell viability assays were used to study the biocompatibility. Finally, the corrosion behaviour of HAp-coatings/Ti6Al4V system was researched by means of Electrochemical Impedance Spectroscopy (EIS. The obtained results showed that the prepared powders were nanocrystalline HAp with little deviations from that present in the human bone. All the prepared HAp coatings deposited on Ti6Al4V showed well-behaved biocompatibility, good bioactivity and corrosion protection properties.

The Development of the Low-Cost Titanium Alloy Containing Cr and Mn Alloying Elements

Science.gov (United States)

Zhu, Kailiang; Gui, Na; Jiang, Tao; Zhu, Ming; Lu, Xionggang; Zhang, Jieyu; Li, Chonghe

2014-04-01

The α + β-type Ti-4.5Al-6.9Cr-2.3Mn alloy has been theoretically designed on the basis of assessment of the Ti-Al-Cr-Mn thermodynamic system and the relationship between the molybdenum equivalent and mechanical properties of titanium alloys. The alloy is successfully prepared by the split water-cooled copper crucible, and its microstructures and mechanical properties at room temperature are investigated using the OM, SEM, and the universal testing machine. The results show that the Ti-4.5Al-6.9Cr-2.3Mn alloy is an α + β-type alloy which is consistent with the expectation, and its fracture strength, yield strength, and elongation reach 1191.3, 928.4 MPa, and 10.7 pct, respectively. Although there is no strong segregation of alloying elements under the condition of as-cast, the segregation of Cr and Mn is obvious at the grain boundary after thermomechanical treatment.

Effects of surface treatments on bond strength of dental Ti-20Cr and Ti-10Zr alloys to porcelain

International Nuclear Information System (INIS)

Lin, Hsi-Chen; Wu, Shih-Ching; Ho, Wen-Fu; Huang, Ling-Hsiu; Hsu, Hsueh-Chuan

2010-01-01

The purpose of this study was to investigate the effect of surface treatments, including sandblasting and grinding, on the bond strength between a low-fusing porcelain and c.p. Ti, Ti-20Cr and Ti-10Zr alloys. The surface treatments were divided into 2 groups. Grinding surface treatment was applied to the first group, which served as the control, and sandblasting was applied to the second group. After treatment, low-fusing porcelain (Titankeramik) was fired onto the surface of the specimens. A universal testing machine was used to perform a 3-point bending test. The metal-ceramic interfaces were subjected to scanning electron microscopic analysis. Of the sandblasted samples, the debonding test showed that Ti-20Cr alloy had the strongest (31.50 MPa) titanium-ceramic bond (p < 005), followed by c.p. Ti (29.4 MPa) and Ti-10Zr (24.3 MPa). Of the grinded samples, Ti-20Cr alloy showed 27.3 MPa titanium-ceramic bond (p < 005), followed by c.p. Ti (14.3 MPa) and Ti-10Zr (failure). The SEM micrographs of the metal surface after debonding showed residual porcelain retained on all samples. On the whole, sandblasting surface treatment appears to have had a more beneficial effect on the Ti-ceramic bond strength than grinding surface treatment. Furthermore, surface treatment of Ti-20Cr with either grinding or sandblasting resulted in adequate bond strength, which exceeded the lower limit value in the ISO 9693 standard (25 MPa).

Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

Science.gov (United States)

Khor, K A; Gu, Y W; Pan, D; Cheang, P

2004-08-01

Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA

Cyclic deformation of dissimilar welded joints between Ti–6Al–4V and Ti17 alloys: Effect of strain ratio

Energy Technology Data Exchange (ETDEWEB)

Wang, S.Q. [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 127 Youyi Road, Xi' an 710072 (China); Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Liu, J.H., E-mail: jinhliu@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 127 Youyi Road, Xi' an 710072 (China); Lu, Z.X. [Department of Materials Science and Engineering, Xi' an University of Technology, 5 Jinhuanan Road, Xi' an 710048 (China); Chen, D.L., E-mail: dchen@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)

2014-03-01

Cyclic deformation characteristics of electron beam welded (EBWed) joints between Ti–6Al–4V and Ti17 (Ti–5Al–4Mo–4Cr–2Sn–2Zr) titanium alloys were evaluated via strain-controlled low-cycle fatigue tests at varying strain ratios at a constant strain amplitude. The welding led to a significant microstructural change across the dissimilar joint, with hexagonal close-packed (HCP) martensite α' and orthorhombic martensite α″ in the fusion zone (FZ), α' in the heat-affected zone (HAZ) of Ti–6Al–4V side, and coarse β in the HAZ of Ti17 side. A distinctive asymmetrical hardness profile across the joint was observed with the highest hardness in the FZ and a lower hardness in the HAZ of Ti17 side than in the Ti17 base metal (BM), indicating the presence of soft zone. The strength and ductility of the dissimilar joint lay in-between those of two base metals (BMs). Unlike wrought magnesium alloys, the Ti–6Al–4V BM, Ti17 BM, and joint basically exhibited symmetrical hysteresis loops in tension and compression in the fully reversed strain-controlled tests at a strain ratio of R{sub ε}=−1. At a strain ratio of R{sub ε}=0 and 0.5, a large amount of plastic deformation occurred in the ascending phase of the first cycle of hysteresis loops of Ti–6Al–4V BM, Ti17 BM, and joint due to the high positive mean strain values. Fatigue life of the joint was observed to be the longest at R{sub ε}=−1, and it decreased as the strain ratio deviated from R{sub ε}=−1. A certain degree of mean stress relaxation was observed in the non-fully reversed strain controlled tests (i.e., R{sub ε}≠−1). Fatigue failure of the dissimilar joints occurred in the Ti–6Al–4V BM, with crack initiation from the specimen surface or near-surface defect and crack propagation characterized by fatigue striations.

The development of the rotational friction welding process for the welding of γ-TiAl-casting alloy Ti-47Al-3.5(Mn+Cr+Nb)-0.8(B+Si) to Ti6Al4V. Pt. II; Prozessentwicklung zum Rotationsreibschweissen der γ-TiAl-Feingusslegierung Ti-47Al-3.5(Mn+Cr+Nb)-0.8(B+Si) mit Ti6Al4V. T. II

Energy Technology Data Exchange (ETDEWEB)

Ventzke, Volker; Riekehr, Stefan; Horstmann, Manfred; Kashaev, Nikolai; Brokmeier, Heinz-Guenter; Huber, Norbert [Helmholtz-Zentrum Geesthacht GmbH, Zentrum fuer Material- und Kuestenforschung, Geesthacht (Germany). Inst. fuer Werkstoffforschung, Werkstoffmechanik

2014-07-01

At process temperatures of T > T{sub β}, the globular and fine grained microstructure of the Titanium alloy Ti6Al4V supports the occurrence of super-plasticity and deformation within the β phase region. This led to one sided shortening of the welded joints combined with the formation of weld flash. As a result of this no evening out of temperature across the forging surface between the γ-TAB cast alloy and Ti6Al4V alloy sides of the joint was able to take place, as a result of which the friction weld seam produced became symmetrically wedge shaped about the axis of rotation. Thereby the γ-TAB cast alloy side of the joint became only slightly compressed exhibiting no appreciable signs of deformation. In the radial direction on the γ-TAB side of the joint close to the forged surface neither the hardness nor the microstructure were homogeneous. Without pre-heating the fine ground, lapped and homogenised γ-TAB weld specimens at a temperature of 800 C above the brittle - ductile transformation transition temperature it was not possible to prevent the occurrence of boundary surface cracking on the outside, micro-voids and inter-lamellar cracking on the γ-TAB side solely by varying the welding parameters. The pre-heating of the γ-TAB friction weld specimens was a necessary pre-requisite to support the deformation of the γ-TAB side of the welded joint and the formation of weld flash during the friction welding process. (orig.)

Effect of microstructure and cutting speed on machining behavior of Ti6Al4V alloy