NbC添加Fe-Mn-Si基形状記憶合金における形状記憶特性改善のメカニズム

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]f//[100]NbC, (001)f//(001)NbC are partially coherent with the matrix showing the misfit dislocations on every five (002)f layers. It was also found that the pre-warm rolling prior to the aging refines the NbC carbides into as small as about 5 nm and makes their distribution homogeneous. It was statistically clarified that the deformation microstructures of the Fe-Mn-Si-based alloys containing finely dispersed NbC carbides exhibit the nano-sized mono-partial 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.