Deformation behaviors at various temperatures and corresponding microscturcures of Ti ₃₆Ni ₄₉Hf ₁₅ alloy

Abstract
The deformation behaviors at various temperatures and corresponding microstructures of Ti ₃₆Ni ₄₉Hf ₁₅ high temperature shape memory alloy had been studied. The tensile behavior of the Ti ₃₆Ni ₄₉Hf ₁₅ alloy is characterized by continuous yielding and high work hardening in the temperature range from 293 K to 673 K. The critical stress for martensite variant reorientation is relatively high and a maximum elongation of about 30% is observed at about 510 K. No superelasticity is observed. The substructure of SIM and deformed SIM in the present alloy is (001) compound twin. Martensite variants are (011) type I twin related. Further increasing the déformation temperature and strain, the preferential oriented SIM gradually develop to martensite variants with variant-crack/variant-intersect morphologies.