Remarkable improvement of recovery stress of Fe-Mn-Si shape memory alloy fabricated by equal channel angular pressing

Effects of equal channel angular pressing and subsequent annealing temperature on the recovery stress of Fe-19.04Mn-4.98Si-8.50Cr-4.59Ni alloy were studied. The results show the maximum recovery stress σm and the room recovery stress σr of the as-pressed specimen increase firstly and then decrease with increase of annealing temperature. σm and σr of the as-pressed specimens annealed at optimal temperature 873 K are 260 MPa and 261 MPa higher than that of the as-quenched ones, respectively. The reason is that as-pressed alloys have higher yield strength and lower Ms temperature, suppressing the plastic deformation and the γ → ɛ phase transformation induced by the recovery stress in cooling.