DEVELOPMENT OF FE-BASED SHAPE MEMORY ALLOYS ASSOCIATED WITH FACE-CENTERED CUBIC HEXAGONAL CLOSE-PACKED MARTENSITIC TRANSFORMATIONS .1. SHAPE MEMORY BEHAVIOR

As part of a study on newly developed Fe-based shape memory alloys associated with face-centered cubic-hexagonal close-packed (fcc-hcp) martensitic transformations, the shape memory behavior is reported and various physical factors influencing it discussed, based on experimental results from dilatometry and bending tests. It is shown that the alloys studied exhibit a good shape memory effect (SME) without special training. The SME is significantly improved by prestraining at low temperatures. A higher net reversible strain is made available by over-prestraining, although the fully reversible prestrain usually does not exceed 2 pct. Super-elasticity, the two-way shape memory, and a softening effect of the matrix at low temperatures are briefly discussed.