Influence of crystal anisotropy on deformation behaviors in nanoscratching of AlN

In this paper molecular dynamics simulations are carried out to study the influence of crystal anisotropy on deformation behaviors in the nanoscratching process of AlN. We investigate the scratching process of AlN(0001), AlN(10$\overline{1}$0) and AlN($\overline{1}$2$\overline{1}$0) surfaces, respectively. It is found that there exists significant anisotropy of the deformation behaviors of AlN for various crystal orientations in the scratching process. The defects evolution, surface topographies, scratching forces and pile-up in the scratching process are closely related to the crystal orientations of AlN workpiece. We observe that the dislocation activities in the scratching process have different characteristics for different crystal orientations of AlN. We also find that many atoms accumulate around the scratch groove evenly in scratching the AlN(0001) surface, while obvious chips are formed in front of the abrasive in scratching the AlN(10$\overline{1}$0) and AlN($\overline{1}$2$\overline{1}$0) surfaces. Furthermore, the average friction force is the smallest for the AlN(0001) surface and the biggest for the AlN(10$\overline{1}$0)surface. However, the average normal force is the biggest for the AlN(0001) surface and the smallest for the AlN($\overline{1}$2$\overline{1}$0) surface. In addition, the pile-up height is the largest in scratching AlN($\overline{1}$2$\overline{1}$0) surface and the smallest in scratching AlN(0001) surface.