X-ray Analysis for Stress-Induced Martensitic Transformation in Fe-Mn-Si Based Shape Memory Alloy

The stress-induced martensitic transformation in Fe-17Mn-5Si-10Cr-4Ni and Fe-17Mn-5Si-2Cr-2Ni-1V shape memory alloys have been quantitatively analyzed by means of XRD analysis. It is found that in Fe-17Mn-10Cr-5Si-4Ni alloy, the volume fraction of stress induced e martensite reaches its maximum value of about 64% under a tensile deformation of about 6% at room temperature. As pre-strain exceeds 5%,α′ martensite appears and grows quickly in the alloy. The results prove that the γ→e→α′ martensitic transformation occurs in Fe-Mn-Si alloy under large deformation. The amount of stress-induced e martensite in the Fe-17Mn-5Si-2Cr-2Ni-1V alloy deformed at room temperature is more than that in the Fe-17Mn-5Si-10Cr-4Ni alloy and no α′ martensite is observed even under a deformation more than 10%. The stress-induced martensitic transformation in Fe-Mn-Si based shape memory alloy can be enhanced by decreasing the deformation temperature.