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采用通过镍的热扩散在钛的表面上生成TiNi金属间化合物层的方法,解决了钛耐磨性差和无淬火硬化性两个问题。研究结果表明,TiNi表面层具有淬火硬化性,表面淬火硬度(HRc)可达50以上,比基体(纯钛)高3倍多,在200℃下硬度稳定。在TiNi层内,富镍区有淬火硬化性,而贫镍区无淬火硬化性。本研究认为通过快冷保留到室温的过饱和置换型结构缺陷导致淬火硬化。当淬火温度低于800℃时,淬火硬度的急剧变化可能与介稳定过渡相有关。
A method of forming a TiNi intermetallic compound layer on the surface of titanium by thermal diffusion of nickel solves two problems of poor wear resistance and non-quench hardening properties of titanium. The results show that the surface layer of TiNi has the property of quench hardening, the surface hardness (HRc) can reach more than 50, which is more than three times higher than that of the substrate (pure titanium) and the hardness is stable at 200 ℃. Within the TiNi layer, the nickel-rich zone is quench-hardenable and the nickel-poor zone is not quench-hardenable. This study suggests that quench hardening results from supersaturated displacement type structural defects that are rapidly cooled to room temperature. When the quenching temperature is lower than 800 ℃, the rapid change of quenching hardness may be related to metastable transition phase.