Investigations of Effects of Intermetallic Compound on the Mechanical Properties and Shape Memory Effect of Ti-Au-Ta Biomaterials.

Wan-Ting Chiu,Tomonari Inamura,Kota Fuchiwaki,Masaki Tahara,Hideki Hosoda,Akira Umise

doi:10.3390/ma14195810

Abstract

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti–Au–Ta SMAs, which also possess high X–ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti–Au–Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta; in addition, obvious improvements of the alloy performances of the ternary Ti–Au–Ta alloys were confirmed while compared with that of the binary Ti–Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti–4 at.% Au–30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti–4 at.% Au–20 at.% Ta alloy during unloading of an externally applied stress.

Highlights

Shape memory alloys (SMAs) have attracted much attention in the biomedical and biomaterials communities due to their functionalities, such as shape memory effect (SME) and superelastic (SE) behavior, which could be manipulated by controlling their operation temperature and externally applied stress [1,2,3]
Based on the aforementioned prerequisites, Au is a potential candidate to enhance the properties of the β–Ti shape memory alloys (SMAs) towards biomedical applications; the binary Ti–Au–based alloy was chosen in this work
Cold–rolling was thereafter conducted until the reduction in thickness reached 98%

Summary

Introduction

Shape memory alloys (SMAs) have attracted much attention in the biomedical and biomaterials communities due to their functionalities, such as shape memory effect (SME) and superelastic (SE) behavior, which could be manipulated by controlling their operation temperature and externally applied stress [1,2,3]. Based on the aforementioned prerequisites, Au is a potential candidate to enhance the properties of the β–Ti SMAs towards biomedical applications; the binary Ti–Au–based alloy was chosen in this work. Tantalum, which is known as a β–stabilizer, was chosen in this study for the manipulation of the functionalities of the Ti–Au–based SMA by tuning its martensite transformation start temperature (Ms) [8]. This study investigated the unexplored effects of the Ta addition on the phase constituents, phase transformation, mechanical properties, shape memory effect, and superelasticity of the binary Ti–Au–based SMAs. In this study, it was found that with the addition of the Ta element to the near– eutectoid Ti–Au alloy, the functionless α–massive martensite was successfully transformed into the functional β–parent phase. More results concerning the Ti–Au–Ta–based alloys and their high–order systems will be published in the future

Materials and Methods

Cold Workability

Phase Identification

Cyclic Loading–Unloading Teennssiillee TTeessttss