Crystallographic effect on subsurface damage formation in silicon microcutting

Nanoprecision plunge cutting tests were carried out on single-crystal silicon (0 0 1) samples along various directions at different tool rake angles, and subsurface damage was characterized by cross-sectional transmission electron microscopy and laser micro-Raman spectroscopy. It was found that amorphization. poly-crystallization, dislocation and internal microcracking occurred and these material responses depended strongly on the cutting direction. When cutting in the [1 (1) over bar 0] and [0 (1) over bar 0] directions, deep line defects consisting of microcracks and dislocation groups occurred even when the surface was ductile-cut; while for the [128 (309) over bar 0] direction, the damage depth was reduced by a factor of five. (C) 2012 CIRP.