PREPARATION OF NANO-SIZED SiC REINFORCED NiTi SHAPE MEMORY COMPOSITES AND THEIR MECHANICAL PROPERTIES AND DAMPING BEHAVIOR

Abstract

NiTi shape memory alloys have attracted significant attention for applications in various fields in the past decades. Although porous NiTi alloys exhibit lower density compared with the dense ones, they are inevitably lower in strength, storage modulus and damping capacity. Therefore, it is imperative to study and improve the compressive performance and storage modulus in porous NiTi alloys. In this study, the nano-sized SiC particle reinforced NiTi shape memory alloy based composites (SiC/NiTi) have been successfully fabricated by means of a step powder-sintering method, which show unique characteristics of lightweight, high strength and stable superelasticity. The fabricated SiC/NiTi composites possess almost the same equivalent strength compared with dense NiTi alloys. On the other hand, they are in the nature of higher strength, including compressive strength and equivalent compressive strength, than porous NiTi alloys. Furthermore, the strength increases with increasing contents of SiC particles. It has been indicated that the addition of SiC particles has a slight influence on the phase composition of the SiC/NiTi composites, while the martensitic phase transformation temperatures of the composites keep unchanged compared with the NiTi alloy without SiC reinforcement. Meanwhile, the fabricated composites inherit the high damping performance of the NiTi matrix, and thus exhibit a high storage modulus.