Directional precipitation of carbides induced by γ/ɛ interfaces in an FeMnSiCrNiC alloy aged after deformation at different temperature

Based on the principle of improving shape memory effect (SME) in Fe-based alloys by directional precipitation of carbides induced by γ/ɛ interfaces, the effects of deformation temperature on the γ/ɛ interfaces, carbides precipitation after ageing and SME of an Fe13.53Mn4.86Si8.16Cr3.82Ni0.16C alloy were investigated. The results show that through controlling the amount and direction of γ/ɛ interfaces, the amount and direction of Cr23C6 carbides after subsequent ageing can be controlled. An optimal amount and directionality of carbides for best SME are obtained after deformation at 238 K. Lots of Cr23C6 carbides can increase the strength of austenite and prevent slip deformation. Meanwhile, after deformation again, martensite plates have the uniform direction because Cr23C6 with optimal directionality and their resultant strain fields can prevent the collisions between martensite bands belonging to different areas. Thus, the reversibility of stress-induced martensite can be remarkably improved and the SME is further improved.