水润滑下刻划速度对γ-TiAl合金纳米刻划性能的影响

Effect of Scratching Speed on Nano-scratched Performance of γ-TiAl Alloy Under Water Lubrication

摘要:

γ-TiAl合金具有优异高温轻质特性，但其本征脆性导致精密加工困难。水润滑可降温并缓解摩擦热积聚、刀具磨损及裂纹问题，是极具前景的加工γ-TiAl合金手段。探索了水润滑下单晶γ-TiAl合金纳米刻划速度对材料刻划力、温度变化、塑性变形和表面质 量的影响。结果表明，刻划速度与水润滑共同决定单晶γ-TiAl合金的加工性能与表面质量。划擦速度增大会显著提升划擦力与摩擦热，导致局部升温与应力集中。然而，在水润滑条件下，当水层厚度为1 nm时，基底温度波动较小，具有良好的冷却效果。刻划速度为400 m/s时，水润滑能减轻表面塑性变形与损伤，切屑堆积增多，表面粗糙度降低。实验结果同样说明，刻划速度对表面质量存在显著影响。

Abstract:

γ-TiAl alloys feature superior high-temperature performance and low-density properties. However, the inherent brittleness of γ-TiAl alloys poses significant challenges to precision machining. As a highly promising machining approach, water lubrication enables temperature reduction and mitigates frictional heat accumulation, tool wear, and crack-associated defects. This work investigated the effects of nano-scratching speed on scratching force, temperature evolution, plastic deformation, and surface quality of single-crystal γ-TiAl alloy under water lubrication. The results show that the coupling effect between scratching speed and water lubrication governs the machinability and surface quality of single-crystal γ-TiAl alloys. An increase in scratching speed substantially elevates scratching force and frictional heat, which further induces local temperature rise and stress concentration. In comparison, a 1-nm-thick water lubrication layer yields minor temperature fluctuation of the substrate and delivers favorable cooling capacity. At a scratching speed of 400 m/s, water lubrication alleviates surface plastic deformation and damage, promotes chip accumulation, and reduces surface roughness. Experimental observations further confirm that scratching speed exerts a pronounced effect on surface quality.