Two-way shape memory effect in stress-induced martensite aged Ni50.3Ti32.2Hf17.5 alloy

Abstract This study investigated the effect of stress-induced martensite aging on thermoelastic martensitic transformations in Ni50.3Ti32.2Hf17.5 polycrystals containing nanosized dispersed H-phase particles. It was found that stress-induced martensite aging at 428 K for 12 hours, under an applied tensile stress of 300 MPa, results in an increase of reversible strain (∼37%) with low applied stresses during cooling-heating cycles and induces a tensile two-way shape-memory effect of 2.3% (∼50% of the maximum reversible strain). Moreover, stress-induced martensite aging along with detwinning of (001) compound internal twins under stress provide an increase of temperature intervals of martensitic transformations by 10÷12 K due to accumulation of elastic energy.