Microstructure, mechanical and superelastic behaviors in Ni-free Ti-Zr-Nb-Sn shape memory alloy fibers prepared by rapid solidification processing

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 782; p. 139283
• Main Authors: Li, Shuanglei, Kim, Yeon-wook, Choi, Mi-seon, Nam, Tae-hyun
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 24.04.2020; Elsevier BV
• Subjects: Age hardening; Annealing; Biomedical materials; Fibers; Grain size; Heat treatment; Martensitic transformations; Mechanical properties; Nickel; Niobium; Optical microscopes; Rapid solidification; Room temperature; Shape memory alloy; Shape memory alloys; Superelasticity; Surgical implants; Tensile tests; Ti-Zr-Nb-Sn alloy; Titanium base alloys; Transformation temperature; Yield stress; Zirconium; Mechanical properties; Shape memory alloy; Superelasticity; Rapid solidification; Ti-Zr-Nb-Sn alloy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2020.139283

Ni-free Ti-based shape memory alloy with superior superelasticity is promising and attractive for biomedical applications. In this study, Ti-18Zr-12.5Nb-2Sn (at.%) alloy fibers were prepared by rapid solidification method and then the effect of various heat treatments on phase constitutions, microstructures, mechanical properties, and superelasticity was investigated by means of X-ray diffraction (XRD), optical microscope (OM), transmission electron microscope (TEM) and tensile test. α phase was observed in the 673 K and 773 K annealed alloy fibers, leading to the degraded ductility. The total recovery strain at room temperature decreased, grain size and transformation temperature increased with increasing annealing temperature from 873 K to 1173 K. Athermal ω was observed in the 1173 K annealed alloy fibers. A good combination of clear superelasticity and high yield stress was achieved by annealing at 873 K followed by aging at 573 K due to the combined effect of the age-hardening caused by isothermal ω phase and small grain size, which indicates these alloy fibers have a good potential in biomedical applications.