New structures after martensitic transformation in an Fe-Mn-Si-Cr shape memory alloy

摘要

The stress-induced martensitic transformation and the microstructures of Fe-28Mn-6Si-5Cr (/100) al- loy subject to several training cycles at different temperatures were investigated with transmission electron microscopy (TEM) and X-ray diffraction (XRD) in detail. Some new structures of 4H-(2, 2) and 6H-(3,3) with orthogonal lattice were found, and the corresponding transformation shear models were also proposed. The occurrence of the or- thogonal structures was the result of shear accomodation to the impeded stress-induced γ→ε transformation and the re- verse transformation, and was supposed to b unfavourable to the improvement of shape memory effect (SME).