Influence of temperature, grain size and cobalt content on the hardness of WC-Co alloys

摘要

The Vickers hardness of WC-Co alloys has beenmeasured at temperatures ranging from - 196 to 9000C. The cobaltcontent of the alloys ranged from 10 to 24 vol% and the grain sizefrom 0.5 to 2.3 μm. It was found that, at all cobalt contents and alltemperatures, the decrease in hardness with increasing grain sizecan be approximated by a Hall-Petch type relationship. Up to about6000C the decrease in hardness with increasing temperatureappears to be due mostly to the decrease in the intrinsic hardness ofthe individual phases. Above 6000C the decrease in hardnessappears to be due mostly to easier slip transfer across grainboundaries. Finer grained alloys have been found to preserve theirhardness at high temperature better than coarser grained alloys, atall cobalt contents.