2008 年 49 巻 8 号 p. 1853-1857
Slight amounts of carbon (0.015–0.1 mass%) were added into the Fe-30Mn-6Si-5Cr shape memory alloy. The microstructure, precipitation behaviour and shape memory performance of these Fe59Mn30Si6Cr5CX alloys with various thermo-mechanical treatments were investigated. Experimental results show that two particles, the χ-phase and M23C6 carbide, are observed within the grain-boundary phases. M23C6 carbide only appears in an alloy with high carbon content, but the χ-phase can form in all alloys with low and high carbon contents. The deformation-induced defects in the 10% pre-deformed specimens are preferential sites for nucleation of precipitates (the χ-phase and M23C6 carbide) in the following aging treatment. After 550–800°C aging, the rearranged uniform defects and homogeneous precipitates within the grain interior will strengthen the matrix and increase the shape recovery ability. After 850–900°C aging, both the uniform defects and homogeneous precipitates disappear due to recrystallization, and hence the specimen’s shape recovery ratios are significantly reduced.
