単結晶シリコン超精密切削における延性／ぜい性遷移機構

Abstract

Diamond turning of single-crystal silicon was carried out in the (111) and (001) wafers, and then the influence of the rake angle of the cutting tool on the ductile-brittle transition mechanism was studied. The material removal process occurred more plastically when using a cutting tool with a larger negative rake angle on both wafers. This was mainly due to changes in cutting-force direction with rake angle. In the case of the (001) wafer, the experimental result could clearly be explained by the differences in the tensile stress exerted on the {111} cleavage planes. That is, the amplitude of the tensile stress decreased as the angle between the cutting-force direction and the cutting direction increased. However, ductile-brittle transition behavior in turning the (111) wafer can not be fully explained in the same way. Transmission electron microscopy observations revealed that activated slip systems on the (111) plane parallel to the turned surface helped to promote ductile behavior. These results indicate that ductile-brittle transition depends, not only on the amplitude of the cutting force, but also on the slip systems to be activated