纳米SiC颗粒增强NiTi形状记忆复合材料制备及其力学性能和阻尼行为

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

采用粉末冶金梯级烧结法成功制备出轻质、高强且具有一定孔隙率的纳米SiC颗粒增强NiTi合金基形状记忆复合材料(SiC/NiTi).研究发现,所制备的SiC/NiTi复合材料具有稳定的线性超弹性;SiC颗粒的引入使SiC/NiTi复合材料具有较高的压缩强度和等效压缩强度,且强度随SiC含量的增加而提高.研究还表明,SiC颗粒对合金相组成有一定影响,但复合材料仍具有NiTi合金的马氏体转变特征,并保持NiTi合金的高阻尼特性及较高的存储模量.

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.