ภานุพงษ์ วรินธนาพันธ์. Fabrication of Pseudoelastic Ti-Alloy for Using in Medical Applications. Master's Degree(Biological Engineering). มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี. สำนักหอสมุด. : King Mongkut's University of Technology Thonburi, 2010.
Fabrication of Pseudoelastic Ti-Alloy for Using in Medical Applications
Abstract:
Nowadays, there are many materials which are used in medical applications such as
stainless steel 3 16L, Ti-6A1-4V and other Ti alloys. However, these materials have still
high modulus of elasticity when compare with human 'bone. From this reason, this
research aims to explore the pseudoelasticity from Martensitic transformation in Ti-Nb
alloys in order to obtain a low modulus of elasticity-liked properties. In this study,
pseudoelasticity of Ti-Nb and Ti-Mo alloys was investigated by varying the alloy
composition, reduction ratio of thickness during cold-rolling process, and heat treatment
temperature. Ti- Nb alloys with Nb-content from 22 to 26 at% and Ti-Mo alloys with
Mo-content from 4 to 6 at% were prepared by arc-melting method. Cold rolling
processes were carried out at reduction ratio of 85 to 95 percent for each specimen,
respectively in order to apply the internal stress for introducing metastable phase. After
cold-rolling, specimens were heat-treated at 873K followed by aging at 573 and 673K,
respectively for 3.6 ks in order to obtain precipitation strengthening due to formation of
Omeda phase. Tensile tests were carried out in order to evaluate mechanical properties of
each specimen. In order to investigate the pseudoelasticity, load-unloading tests under
various strains were performed at room temperature. It is found that the pseudoelasticity
can be confirmed in the alloy with Nb-content ranging from 23 to 26.7 at%, while
modulus of elastic due to detwining of martensite variant increase with increasing
reduction ratio. Excellent recovery pseudoelastic strain ratio is confirmed in a Ti-
25.6at%Nb alloy with 85 percent of reduction ratio. Moreover the very low modulus of
elastic can be obtained during the range of reorientation of martensite variants which is
suitable for utilizing as an artificial bone.