Phase Transformations in the Intermetallic Compound TiNi.

Abstract

Survey work has resolved certain reported anomalies in this system. In particular, TiNi was found to undergo two displacive phase transformations at temperatures near room temperature. Below 50°C the pseudo body-centered cubic compound undergoes a gradual distortion in an unusual second order phase transformation producing the "transition phase”, the existence of which is terminated by a typical martensitic burst transform nation at 20°C which produces the "martensitic phase”. The crystal structures of the parent phase and transformation products, and the transformation characteristics have been studied with X-ray and electron diffraction, electron microscopy, electrical resistance and density measurements.