基于分子动力学研究刚性磨粒划擦铝基材料去除行为

目的 实现材料高效去除，避免亚表层严重滑移，以及改善已划擦区表面形貌质量。方法 基于EAM和Morse混合势函数，采用分子动力学法对刚性磨粒划擦Al材料的去除行为展开研究，分析磨粒尺寸、温度、压深、速度对材料去除行为的影响，并提出飞秒激光辅助加热改善材料塑性去除行为的方法。结果 不同划擦因素变化对Al材料去除、表面形貌质量、亚表层滑移等方面影响显著，经飞秒激光辅助处理的表面，在划擦中能有效改善已划擦区的表面形貌质量，降低亚表层滑移程度。增加磨粒尺寸、温度、压深，有利于表面材料去除，更易将磨屑原子向沟槽边缘两侧挤出，造成磨屑堆积程度增加。另外，划擦速度越高，已划擦区的表面形貌质量获得相应改善，并有效减弱了其亚表层滑移程度。相比无激光辅助处理，经过飞秒激光处理的表面，在划擦中不仅有利于提高材料去除率，而且有效降低了磨粒与基底接触区域的应力集中度和亚表层滑移程度，明显改善了已划擦区的表面形貌质量。结论 为了获得较好已划擦区的表面形貌质量，且避免应力集中导致亚表层滑移严重，除了需要考虑飞秒激光辅助加热外，还需权衡加热源区深度尺寸与压深的关系，即宜取辅助热源区深度尺寸上下范围10%作为压深值。

Analysis of Material Remove Behavior Induced by Rigid Abrasive Particle for Aluminum Substrate on Scratching Based on Atomic Simulation

This work aims at Al material removed effectively with some good advantages, such as reduced sub-surface slip and improved surface morphology quality. Thus, molecular dynamics method was applied to investigate the remove behavior of Al material scratched by rigid abrasive particles. Based on EAM and Morse functions, the influence of such crucial factors as abrasive size, temperature, indentation depth, scratching velocity on the remove behavior of Al material was analyzed, thus, the heating source produced by femtosecond laser processing was proposed to improve machined surface quality. It was found that above important factors have obvious influence on remove behavior of Al material, surface morphology quality and sub-surface slip. The scratched surface processed by femtosecond laser will get improved surface morphology quality and reduced sub- surface slip while scratching. At the same time, it shows that it is easier to extrude the wear debris produced to both edges of the groove, resulting in the increase of the wear debris accumulation due to bigger particle size, higher temperature, and larger indentation depth. What is more, the higher scratching velocity is, the scratched surface morphology gets better improvement and the sub-surface slip reduces effectively. Compared with non-laser processing, femtosecond laser processing can not only improve the material removal rate, but also effectively decrease the stress concentration degree and sub-surface slip degree in the contact area between the abrasive particles and the substrate, as well as obviously improve the surface morphology quality of the scratched area. In a word, it is a better strategy to achieve better surface morphology quality and avoid stress concentration through femtosecond laser processing, in connection with the indentation depth, that is, around 10% of the depth size of the assisted heat source area should be taken as the indentation depth.