Phase Constitution and Mechanical Properties of Ti‐Mo‐Sn‐Zr Shape Memory Alloys

Abstract

Effects of Zr addition on the phase constitution and mechanical properties of Ti-5Mo-3Sn (mol%) based shape memory alloys were investigated by X-ray diffraction measurements and tensile tests. It was found that the phase is stabilized by Zr addition and that the maximum lattice deformation strain of Ti-5Mo-3Sn alloy is 6.6%. Ti-5Mo-3Sn alloy exhibited the shape memory effect with shape recovery strain of 4.2 %, while Ti-5Mo-3Sn-6Zr alloy exhibited the superelasticity at room temperature with the shape recovery strain of 4.3 %. However, the shape memory effect and the superelasticity did not appear in 12mol%Zr addition. The slip stress increases from 306 MPa in Ti-5Mo-3Sn alloy to 455 MPa in Ti-5Mo-3Sn-6Zr alloy. Therefore, 6mol%Zr addition is effective to obtain the room temperature superelasticity and to increase the slip stress of Ti-5Mo-3Sn based alloys without degrading transformation strain.