単結晶シリコン超精密切削における微小変形挙動の結晶方位依存性

抄録

The crystallographic orientation dependence of the machinability of single-crystal silicon was studied by molecular dynamics (MD) simulation in the turning process of single-crystal copper from the standpoint of slip deformation behavior. Slip deformation occurred with minimal damage to the work material, as the material removal process was governed by activated slip systems parallel to the turned surface. On the other hand, as other non-parallel slip systems contributed to slip deformation, the turning process advanced with greater damage such as crystal rotation or change in crystal orientation. This agrees with previous experimental results showing that better surfaces were obtained on the (111) wafer than on the (001) wafer at the same depth of cut. MD analysis also revealed that, as slip systems existing on intersecting slip planes were activated simultaneously, glide was restricted in each plane due to their interaction. This in-dicates that ductile-brittle transition is highly dependent, not only on the number of activated slip systems and the amplitude of their Schmid factor, but also on how each slip system is arranged geometrically. Such slip deformation behavior makes it clear why ductile-regime turning can be realized more easily by turning along the [112] direction on the (111) wafer than by turning along the [112] direction.