title: Effect of thermomechanical treatment on the superelasticity of Ti-7.5Nb-4Mo-2Sn biomedical alloy.
abstract: Effects of thermomechanical treatment on the microstructure and superelasticity of Ti-7.5Nb-4Mo-2Sn biomedical alloy were investigated by using XRD measurement, optical microscope (OM), transmission electron microscope (TEM) and tensile tests. The titanium alloy samples were prepared by annealing at a temperature in the range of 600 to 1000°C after severe cold rolling; and the samples that were annealed at 800°C were further aged at 600 and 700°C. The volume fraction of α phases decreased while that of ω phases increase with increasing annealing temperature. The α→β transformation temperature of the alloy was determined to be between 700 and 800°C. The alloy that was annealed at 700°C exhibited a high level of superelasticity with relatively high first yield stress (σSIM) at room temperature because it contained a fine α phase. A certain amount of ω phases also resulted in an increase in σSIM, leading to an improvement in the superelasticity of the alloys that were annealed at 900 and 1000°C. Aging treatment led to the precipitations of α and ω phases in the alloy after annealing at 800°C; and the volume fraction of α phases decreased while that of ω phases increased with increasing aging temperature. Excellent superelasticity with high recovered strain (εrecoverable) and strain recovery rate (η) were obtained in the aged alloy due to the reinforcement of α and ω phases induced by aging treatment. The alloy annealed at 700°C for 0.5h exhibited the best superelasticity in all the thermomechanically treated alloys due to the strengthening from the subgrain refining and the precipitating of fine α phases.
authors.affiliation: Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan, China.
authors.forename: D C
authors.initials: DC
authors.lastname: Zhang
authors.affiliation: Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan, China.
authors.forename: C G
authors.initials: CG
authors.lastname: Tan
authors.affiliation: Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan, China.
authors.forename: D M
authors.initials: DM
authors.lastname: Tang
authors.affiliation: Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Faculty of Material and Optical-electronic Physics, Key Laboratory of Low Dimensional Materials & Application Technology (Ministry of Education), Xiangtan University, Xiangtan, 411105 Hunan, China. Electronic address: lin_j_g@xtu.edu.cn.
authors.forename: J G
authors.initials: JG
authors.lastname: Lin
authors.affiliation: Faculty of Engineering & Industrial Science, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia.
authors.forename: C E
authors.initials: CE
authors.lastname: Wen
mesh_terms: D000497:Alloys / Q000737:chemistry*; D020811:Biomedical Technology; D004548:Elasticity; D006358:Hot Temperature; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D014025:Titanium
keywords: Aging; Annealing; Microstructure; Superelasticity; Titanium alloys