Elastic after-effect in WC/Co cemented carbide

Free-decay internal friction measurements as a function of temperature and frequency have been used to study the inherent viscous behavior of the Co b inder present at grain boundaries of a WC/Co cemented carbide material. The presence of a relaxation peak was related to the micromechanism of anelast ic grain-boundary sliding and a peak-shift analysis was presented as a func tion of frequency. Using the mechanics of the elastic after-effect, both th e viscosity and the activation energy of the intergranular Co binder could be determined. A comparison of the intergranular viscosity data was carried out with data obtained on bulk Co metal both in the high-purity state or i n solid solution with a small volume fraction of WC. The viscosity of the C o binder, as determined by internal friction, showed good agreement with th e bulk Col WC solid solution, whose chemical composition was presumably the closest to the intergranular binder in the cermet material. Based on the a greement between intergranular and bulk viscosities as well as activation e nergy values, it is considered that the present method can be more generall y used in ceramic/metal materials. (C) 1999 Elsevier Science Limited. All r ights reserved.