Effect of α phase precipitation on martensitic transformation and mechanical properties of metastable β Ti–6Cr–3Sn biomedical alloy

Recently among our developed Ti–xCr–3Sn (mol%) alloys, Ti–6Cr–3Sn alloy exhibited excellent mechanical, shape memory and psuedolastic properties due to stress induced martensitic transformation. Then in this study, the effect of α phase precipitation on martensitic transformation and mechanical properties of Ti–6Cr–3Sn alloy was investigated. By ageing at 973 K, α phase precipitation occured at grain boundary and then shape memory effect and pseudoelastic recovered strain related to martensitic transformation reduced and yield stress and UTS increased as compared to the solution-treated conditions. However by ageing at 873 K, the shape memory effect and the pseudoelasticity were drastically degraded and the fracture strain drastically reduced and yield stress increased. It is suggested that to improve the mechanical, shape memory and psuedoelastic properties simultaneously, the control on the size and uniform distribution of α phase precipitation is very important.

► Ti–6Cr–3Sn alloy exhibited shape memory and pseudoelastic properties.
► Shape memory and pseudoelastic properties were found sensitive to the volume fraction and morphology of the α phase.
► Shape memory and pseudoelastic properties were slightly reduced by the grain boundary α phase.
► UTS, yield stress and hardness were improved by ageing due to α phase precipitation.