Abstract
In order to develop the unconventional machining method, the stock-removing and machined-surface properties of Si wafer was investigated by making collide obliquely submicron-sized tungsten and its carbide particles with the velocities of about 100 m/s. The results obtained are as follows : (1) The volume removal per hard carbide particle measured is well approximated by an elastic penetration volume introduced from Hertzian impact theory. This suggests that the removal may be caused by cutting action based on ductile shear fracturing of Si. But the depth of cut estimated with relatively soft tungsten particle became of atomic scale smaller than elastic penetration value, and which may be due to severe plastic flow in the particle. (2) The RHEED observation of the machined Si surface whose roughness is of the order of 10 nm suggests the existence of slightly distorted lattice layer. (3) The phenomenological change from Si removal to particle deposition obviously proceeds at particle incident angle beyond 45°. Such a phenomenon is briefly discussed from a viewpoint of particle-energy consumption by measuring the reflection spectra of post-impact particles.
