How hard metal becomes soft: crystallographic analysis on the mechanical behavior of ultra-coarse cemented carbide

Abstract

Investigation into the temperature dependence of the mechanical behavior of ultra-coarse grained cemented carbide materials is highly demanded due to its service conditions of concurrent applied stress and high temperature. In the present study, based on the designed experiments and microstructural characterization combined with crystallographic analysis, the evolution of slip systems, motion and interaction of dislocations with temperature are quantified for the WC hard phase. Mechanisms are proposed for the formation of the sessile dislocations in the main slip systems at the room temperature and the glissile dislocations in the new slip systems activated at high temperatures. Furthermore, the correlation of the plastic strain and fracture toughness with the temperature-dependent slip activation, dislocation reaction and transformation is explained quantitatively. Enlightened by the present findings, potential approach to enhance the high-temperature strength of ultra-coarse cemented carbides based on WC strengthening was suggested.