等径弯角挤压法制备的TiNi合金的摩擦学性能

Friction Properties of TiNi Alloy Fabricated by Equal Channel Angular Extrusion

采用先进的等径弯角挤压(ECAE)技术对热锻态Ti-50.6%Ni(原子分数)合金进行加工处理,研究了挤压后TiNi合金的伪弹性能及摩擦学性能,探讨了ECAE对TiNi合金摩擦学性能的影响.实验结果表明:高温等径弯角挤压工艺处理显著提高了TiNi合金的摩擦学性能,摩擦系数从0.141下降至0.06左右,磨损量也显著降低.这主要是由于经过等径弯角挤压工艺处理后,TiNi合金的显微组织得到细化,且有弥散、细小的Ti3Ni4第二相析出,对基体起到了强化作用;TiNi合金可恢复应变率从40%增大到63%,改善了TiNi合金的伪弹性能,增强了TiNi合金在摩擦磨损过程中的弹性变形能力,减少了塑性变形,从而提高了TiNi合金的摩擦学性能.通过扫描电子显微镜对TiNi合金磨损后表面形貌的观察发现:原始TiNi合金呈现了明显的磨粒磨损特征,且伴随有大块磨粒剥落和横向裂纹;而经过等径弯角挤压处理后TiNi合金的磨损表面较光滑、平整,呈现较轻微的磨粒磨损特征.

The novel equal channel angular extrusion （ECAE） process was used for hot forged Ti-50.6%Ni alloy. Pseudo-elasticity and friction properties of TiNi alloy after ECAE process were investigated. The effect of ECAE process on friction properties of TiNi alloy was discussed. The results show that the friction properties of TiNi alloy after ECAE process are improved markedly, which is mainly attributed to refined microstructure, the second participates and improved pseudo-elasticity. It enhances elastic deformation ability, reduces plastic deformation, and then increases friction properties of TiNi alloy. It is found through observation of worn surfaces on SEM that the initial TiNi alloy has obvious abrasive wear, with peeling and cracks, while after ECAE treatment, the worn surface of TiNi alloy is smoother, and has slight abrasive wear.