Erosion of copper single crystals under conditions of 90° impact

High purity copper single crystals were eroded parallel to 111] at 90° to the surface with glass spheres 70 μm in diameter travelling at a velocity of 122 m s^?1. Detailed scanning electron microscopy of eroded surfaces together with transmission electron microscopy of both erosion debris and near-surface layers of the target was performed. It was observed that a hilland-valley surface topology developed ; this has not been reported previously and gave rise to a local low angle cutting component of erosion at 90°. Direct evidence was obtained of a transient heating effect from the particle impact as well as the formation of subsurface voids in heavily deformed regions. In addition it was shown that subsurface cracking produced a flaking mechanism of material loss.