不同刻划速度对水润滑下纳米刻划γ-TiAl的影响

Effect of different scratching speeds on nano-scratched γ-TiAl under water lubrication

摘要:

由于γ-TiAl合金优异的高温和轻质性能，其在航空航天领域极具应用潜力。然而，γ-TiAl合金固有的硬脆性给精密加工带来了重大挑战。水润滑可以降低加工温度，能够有助于解决γ-TiAl合金在加工过程中面临的摩擦、热积累和刀具磨损等问题，以及减少裂纹萌生克服γ-TiAl合金的固有脆性问题，这使得水润滑成为γ-TiAl合金加工中非常有前景的一种方式。因此，通过分子动力学（MD）模拟构建水润滑下单晶γ-TiAl合金的纳米刻划模型，系统研究了水润滑下刻划速度对纳米刻划过程中单晶γ-TiAl合金刻划力、基体温度、塑性变形和表面质量的影响。随着刻划速度的增加，刻划力和温度均显著升高。但在水层润滑下，水层厚度为1nm时，基体温度波动小，表现出较好的冷却效果。当刻划速度达到400m/s时，工件表面塑性变形显著加剧，切屑堆积增加，表面粗糙度降低。

Abstract:

Due to the excellent high-temperature and lightweight properties of γ-TiAl alloys, they have great application potential in the aerospace field. However, the inherent brittleness of γ-TiAl alloys poses significant challenges to precision machining. Water lubrication can reduce the processing temperature, which can help solve the problems of friction, heat accumulation, and tool wear faced by γ-TiAl alloys during processing, as well as reduce crack initiation and overcome the inherent brittleness of γ-TiAl alloys. This makes water lubrication a very promising method in the processing of γ-TiAl alloys. Therefore, a molecular dynamics (MD) simulation was used to construct a nano-scratching model of single-crystal γ-TiAl alloy under water lubrication, and the effect of scratching speed on the scratching force, substrate temperature, plastic deformation, and surface quality of single-crystal γ-TiAl alloy during nano-scratching was systematically studied under water lubrication. As the scratching speed increased, both the scratching force and temperature increased significantly. However, under water layer lubrication, when the water layer thickness was 1nm, the substrate temperature fluctuation was small, showing a good cooling effect. When the scratching speed reached 400m/s, the plastic deformation of the workpiece surface was significantly aggravated, the accumulation of chips increased, and the surface roughness decreased.