Elastic Properties of NiTi as a Function of Temperature

Young's modulus, shear modulus, and internal friction of the intermetallic compound NiTi have been measured as a function of temperature from about −180° to 600°C, in the kilocycle-per-second range. Annealed and cold-worked specimens were used. All the specimens showed the same general pattern, with a minimum in elastic moduli occurring about 70°–140°C, depending upon the particular specimen, and a maximum in internal friction occurring some 50°C below the minimum in elastic modulus. Young's modulus was the same for all the specimens (694 kbar) within experimental error, but the shear modulus of the cold-worked specimens was more than 10% higher than that for the annealed specimens.