Effect of Low-Temperature Phase Changes on the Mechanical Properties of Alloys near Composition TiNi

X-ray diffraction and dilation studies have shown that alloys near the stoichiometric TiNi composition undergo transformation into the related phases Ti2Ni and TiNi3 at low temperatures. The main factors controlling these phase transformations are alloy composition, temperature, and mode of plastic deformation. In plastic deformation, tensile or compressive stressing produced separate and unlike decomposition phases; this finding was dramatically demonstrated by unique temperature-sensitive dimensional changes in plastically deformed specimens. Changes of large magnitude in vibration damping have also been noted and appear related to variations in the phase equilibria of the system.