Influence of ageing after deformation on shape recovery ration and transformation temperature in FeMnSiCrNi alloy

To further enhance shape memory effect(SME) for Fe-14Mn-6Si-8Cr-5Ni alloys,the alloy under solid solution condition was aged after deformation,and the influence of ageing temperature and ageing time on shape recovery ration and transformation temperature in an alloy were investigated by means of optical microscopy,XRD and TEM.The results revealed that the shape recovery ration for an alloy aged at 600 ℃ for 10 min after 10% tensile deformation greatly rose from 48% to the maximum value of 84.7% under solid solution condition and the γ→ε martensite transformation starting temperature Ms dropped from 34 ℃ to 13.2 ℃.The principal reasons that make the remarkable improvement in shape recovery ration are that thermal induced ε martensite in an alloy through above treatments disappears and the constituent phases are austenite and much directional α'martensite.This structure is just advantageous to stress-induced γ→ε martensite transformation and reverse transformation.