Microstructural analysis of the stress-induced ε martensite in a Fe-Mn-Si-Cr-Ni shape memory alloy:: Part I -: calculated description of the microstructure

The gamma(f.c.c.)-epsilon(h.c.p.) martensitic transformation is achieved by the introduction of stacking faults on each second compact plane of the f.c.c. structure. These stacking faults are created by the motion of Shockley partial dislocations. Depending on the Burgers vector of these dislocations, the martensite does not require a macroscopic shape change (self-accommodated martensite) or a homogeneous lattice shape change (monopartial martensite). Based on the monopartial nature of the stress-induced martensite, a model describing the martensitic morphology in the Fe-Mn-Si based shape memory alloys is presented. The theoretical results are compared with some observations in a Fe-Mn-Si-Cr-Ni shape memory alloy. (C) 1998 Elsevier Science S.A.