Grain refinement and carbide precipitation in Fe–Mn–Si–Cr–Ni–C shape memory alloy fabricated by equal channel angular pressing

The present paper studied the grain refinement and carbides precipitation in a Fe–Mn–Si–Cr–Ni–C alloy aged after equal channel angular pressing (ECAP). The results show that after ECAP and subsequent aging, the average size of the grain is ∼10 μm. Meantime, defects introduced by ECAP can decrease the activation energy for nucleation of the carbides and thus more carbides are produced inside the grains and the grain boundary. Grain refinement together with second phase hardening effectively improves the strength of matrix. Consequently, the shape memory ratio of the alloy aged after ECAP is up to 89·4% when prestrain is 4·33%, being 40% higher than those aged without ECAP.