HIGH-TEMPERATURE TENSILE DUCTILITY IN WC-CO CEMENTED CARBIDES

High-temperature tensile deformation in WC-Co was investigated at temp eratures between 1150 degrees C and 1250 degrees C. The flow stress is sensitive to temperature, strain rate, volume fraction-of binder, and the addition of other carbides. The stress-strain rate relationship-i s divided into three regions at each temperature as in superplastic me tals. A large tensile elongation over 100 pct was first obtained in WC -6Co and WC-13Co (wt pct) at temperatures of 1200 degrees C. Contrary to superplastic metals, the largest tensile elongation is not obtained in region II but on the border of regions I and II. The failure mode changes from necking in region I to sharp cracking in region II.