Inelastic deformation under indentation and scratch loads in a ZrB_2-SiC composite

摘要

Inelastic deformation features induced in an ultra-high temperature ceramic composite, ZrB_2-SiC, due to static indentation (rate of deformation of the order of 10~(-5)s~(-1)), dynamic indentation (rate of deformation of the order of 10~3 s~(-1)), and high-velocity scratch (500 mm/s) experiments are presented. It was found that this ceramic composite has up to 30 percent higher dynamic hardness compared to static hardness. Dynamic indentations resulted in extensive transgranular microcracking within the indented regions compared to static indentations. In addition, significant plastic deformation features in terms of slip-line formation were observed within statically and dynamically indented regions. The high-velocity scratch studies revealed extensive transgranular microcracking perpendicular to the scratch direction and slip-lines in and around the scratch path. Preliminary transmission electron microscopy (TEM) observations from regions of slip-lines surrounding the scratch grooves revealed dislocation activity in the composite.