Effect of Shape Memory Heat Treatment on Microstructures and Mechanical Properties of Powder Metallurgy TiNi Shape Memory Alloy

Abstract

The shape memory heat treatment effects on the microstructures and mechanical properties of TiNi shape memory alloys fabricated by powder metallurgy (PM) process were investigated in this study. Through the optimization of the shape memory heat treatment conditions, PM TiNi alloy showed a high plateau stress of 454 MPa and good shape recovery of 96.4% in 8% tensile strain applied via the heat treatment at 773 K for 10 min. A longtime heat treatment applied to PM TiNi alloys caused an increase of the amount of Ti₃Ni₄ precipitates in the TiNi matrix, and resulted in the relative decrease of Ni solid solution in the matrix which caused the decrease of the plateau stress.

 

This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 65 (2018) 85–90.