Indentation on monocrystalline copper at cryogenic and ambient temperature

Indents of monocrystalline copper on (110) crystal face were conducted at 150 K and 298 K. The residual indents were studied using scanning electron microscope (SEM) and atomic force microscope (AFM) methods. Interesting phenomenon, performed as ridges inside the indents, was observed at 150 K. Combined with cross-section transmission electron microscopy (XTEM), the crystal structure of subsurface of impressions at two temperatures were investigated. No twin crystal was identified beneath the ridges and the ridges were considered as inner-slip-bands, caused by concentration of geometrically necessary dislocations (GNDs).