原位合成NiTi-TiB_2复合材料的显微组织与性能

Microstructure and properties of in-situ synthesized NiTi-TiB_2 composite

采用电弧熔炼Ti、Ni和B的方法,原位合成B含量不同的3种NiTi-TiB2复合材料,对复合材料的显微组织、成分及压缩力学性能进行研究。结果表明:材料中NiTi与TiB2之间为冶金结合,结合界面致密无孔隙,克服了以往研究中非原位复合材料常见的界面结合差以及致密度低等缺点。当B的摩尔分数超过6%以后,组织中出现粗大的Ti2Ni脆性枝晶,并伴随材料压缩性能的降低。样品力学性能的恶化与粗大TiB2陶瓷以及Ti2Ni脆性枝晶的形成有关。

Three in-situ NiTi-TiB2 composites with different B contents were prepared by arc melting of Ti, Ni and B. The microstructure, composition and compress property were tested. The results show that TiB2 ceramic phase disperses in NiTi shape memory alloy matrix, with metallurgical bonding interface, and no pore is observed, which can overcome the shortcomings in traditional ex-situ composites, such as poor interfacial bonding, low density, porosity, and so on. However, the coarse TiB2 ceramic and brittle Ti2Ni dentrite with tens of micrometers size is observed when the B content is over 6%(mole fraction), which causes compression performance deterioration of the composite.