THE SURFACE PERFORMANCE OF SHOT PEENED AND ION IMPLANTED NiTi SHAPE MEMORY ALLOY

摘要

Equiatomic NiTi shape memory alloy in austenitic and martensitic forms has been modified by shot peening with glass media and by N~+ ion implantation. The effect upon microstructure, surface hardness and coefficient of friction was measured, along with the effect of the two treatments upon the shape memory behaviour. Examination using transmission electron microscopy (TEM) showed amorphous regions within the surfaces treated by both peening and ion implantation. In addition, peened and ion implanted samples showed similar increases in surface hardness and reduced surface friction coefficient. Differential scanning calorimetry showed that both surface treatments had no effect upon the bulk shape memory phase transformation behaviour.