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NiTi形状记忆合金具有诸多功能特性,如超弹性、高阻尼性和形状记忆效应等,因而得到广泛应用。TiB_2陶瓷具有高硬度、高耐磨性和高模量特性,但其脆性限制了其应用。将记忆合金与TiB_2陶瓷复合,有望获得超常性能:兼具高强度、高模量、超弹性、高硬度、高耐磨等力学性能,以及因耦合而产生的崭新功能特性。采用电弧熔炼Ti、Ni、B的方法,原位合成NiTi-TiB_2复合材料,对B含量不同的6种复合材料的可逆马氏体相变、显微组织、成分及硬度进行了初步探索。结果显示,NiTiB合金中含有NiTi记忆合金相以及Ti_2Ni和TiB_2陶瓷相。随着B含量升高,TiB_2陶瓷相由线状变化为粗大的块状,并且Ti_2Ni和TiB_2陶瓷相含量也随之逐渐升高。NiTi基体具有良好的抑制裂纹扩展功能。含B量为4%、6%和14%样品的硬度都普遍高于二元NiTi记忆合金,其中含14%B样品最高硬度与陶瓷相当。
NiTi shape memory alloy has many functions such as super elasticity, high damping and shape memory effect, which are widely used. TiB 2 ceramic has high hardness, high wear resistance and high modulus properties, but its brittleness limits its application. The memory alloy and TiB_2 ceramic composite, is expected to obtain extraordinary performance: both high strength, high modulus, super elasticity, high hardness, high wear resistance and other mechanical properties, as well as coupled with the resulting new features. The NiTi-TiB_2 composites were synthesized by in situ arc melting of Ti, Ni and B, and the reversible martensitic transformation, microstructure, composition and hardness of six composites with different B contents were explored. The results show that, NiTiB alloy containing NiTi memory alloy phase and Ti_2Ni and TiB_2 ceramic phase. With the increase of B content, the TiB_2 ceramic phase changed from linear to coarse block, and the content of Ti_2Ni and TiB_2 ceramic phases gradually increased. NiTi matrix has a good crack growth inhibition. The hardness of samples containing 4%, 6% and 14% B was generally higher than that of binary NiTi memory alloys, with the highest hardness of 14% B samples being comparable to that of ceramics.