Mechanism of the Improvement of Shape Memory Effects in NbC Containing Fe-Mn-Si-Based Shape Memory Alloys

摘要

High-resolution transmission electron microscopy revealed that the NbC carbides precipitating in Fe-Mn-Si-based shape memory alloys in the orientational relationship of [100]{sub}f//[100]{sub}(Nbc), (001){sub}f//(001){sub}(Nbc) are partially coherent with the matrix showing the misfit dislocations on every five (002){sub}f layers. It was also found that the pre-warm rolling prior to the aging refines the NbC carbides into sizes as small as about 5 nm and produces a homogeneous distribution. It was statistically clarified that the deformation microstructures of the Fe-Mn-Si-based alloys containing finely dispersed NbC carbides exhibit nano-sized monopartial stacking martensite plates, similar to those of the conventional Fe-Mn-Si-based alloys subjected to the training treatment. These microstructural features are considered to improve the shape memory properties of the alloys.