| The effect of heat treatment condition on the martensitic transformation behavior and shape memory effect in Fe-15Mn-5Cr-5Co-3Si alloy has been studied by microscopy and calorimetry. The grain size increased with the increase in heat treatment temperature and holding time. Three types of transformation behavior, such as no martensitic transformation, r→ε and r→ε→α` were observed in increasing order of grain size. The r phase did not seem to transform directly to α`, for α` martensite was found only in the a martensite plates. The orientation relationships between the ε and the α` martensites were [011] ε∥ [311]α`, (1￣00) ε∥ (1￣12) α` and [011] ε∥ [111] α`, (1￣11￣) ε ∥ (1￣01) α`. The Ms temperature of r→ε transformation remained almost constant, while that of ε→α` transformation increased rapidly with the increase in grain size. As the heat treatment temperature and holding time increased, the shape memory effect became worse. This could be attributed to the reduction of r phase contributing to the shape memory effect and the easiness of movement of dislocations during the deformation. |
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