SLIP SYSTEMS AND PLASTIC-DEFORMATION OF SILICON-CARBIDE SINGLE-CRYSTALS AT HIGH-TEMPERATURES

Knoop hardness measurements have been made on the (0001), {101̄0} and {1120} planes of 6H-SiC single crystals in the temperature range from room temperature to 1600 °C. The hardness varies with the orientation of the long axis of the indenter on each plane. For all planes the hardness anisotropy is dependent on the temperature and the converse anisotropy was observed at temperatures below and above about 300-400 °C. It is concluded from the hardness anisotropy that the active slip system of 6H-SiC is {101̄0}〈112̄0〉 near room temperature and (0001)〈112̄0〉 at high temperatures. At about 300-400 °C both the basal and prismatic slip systems are operative. The 〈112̄0〉 slip lines are observed around Knoop and Vickers indentations only on the prismatic planes at approximately 800 °C, above which they become pronounced with increasing temperature. This suggests that the plasticity of 6H-SiC will increase substantially above 800 °C. © 1979.