Phase transformation, oxidation and shape memory properties of Ti-50Au-10Zr alloy for high temperature applications

In this study, we investigated the phase transformation, oxidation and high temperature mechanical and shape memory properties of Ti-50Au-10Zr (all compositions in atomic%) alloy. Thermo-mechanical analyzer (TMA) was used not only for phase transformation but also for the measurement of shape memory effect and oxidation behavior in air environment. Ti-50Au-10Zr exhibited lower martensitic transformation temperature of 758 K than TiAu stoichiometric alloy exhibiting 870 K since Zr addition stabilizes B2 parent phase. Oxidation was initiated at 873 K that was about 100 K higher than the austenite finish temperature, indicating no such oxidation problems for practical use. Shape memory effect was improved by partial substitution of Ti with Zr in Ti-50Au-10Zr alloy. Compression test of Ti-50Au-10Zr revealed high compressive strength of 1239 MPa of martensite at 691 K (=Mf − 50 K) and 924 MPa of B2 parent phase at 834 K (=Af + 50 K) in comparison with Ti-50Au. It is concluded that Zr is effective to improve the mechanical and shape memory properties of TiAu alloy, and that Ti-50Au-10Zr shape memory alloy has potential for high temperature (∼650-850 K) practical applications.