Strengthening of β Ti–6Cr–3Sn alloy through β grain refinement, α phase precipitation and resulting effects on shape memory properties

Our recently developed Ti–6Cr–3Sn alloy exhibited shape memory effect and large fracture strain. However Ti–6Cr–3Sn alloy exhibited partial shape memory effect and low ultimate tensile strength (UTS). Then in this study, effects of decrease in β grain size on the mechanical and shape memory properties of β Ti–6Cr–3Sn alloy were investigated. Results of decrease in β grain size were also compared with our recently reported uniform α phase precipitated Ti–6Cr–3Sn alloy. It was investigated that decrease in β grain size was found effective in improving the strength, fracture strain and shape memory properties of β Ti–6Cr–3Sn alloy due to the increase in critical stress for slip deformation. On the other hand, uniform precipitation of α phase in β matrix of Ti–6Cr–3Sn alloy was found much more effective than decrease in β grain size in improving the strength and shape memory properties of β Ti–6Cr–3Sn alloy. However fracture strain of uniform α phase precipitated Ti–6Cr–3Sn alloy was lower than coarse and fine β grain Ti–6Cr–3Sn alloy. It is concluded that decreasing β grain size was found as effective way to improve the mechanical and shape memory properties altogether of β Ti–6Cr–3Sn shape memory alloy. However decrease in β grain size was found less effective than our recently reported effect of uniform precipitation of α phase in β matrix of β Ti–6Cr–3Sn alloy.