Phase transitions at grain boundaries in WC-Co and internal friction peak analysis

High-temperature relaxations in WC-Co have been investigated by mechanical spectroscopy. A broad relaxation peak P4 visible in frequency scans is attributed to WC-WC grain boundary sliding. This peak can be deconvoluted into four relaxation peaks with a strength that depends on temperature. The variations of their relative relaxation strength variations can be attributed to structure changes in the WC-WC grain boundaries due in particular to cobalt infiltration. The subdivision of the peak P4 into several relaxation peaks with varying strengths provides an explanation for the measure of an apparent activation energy that has been formerly attributed to this peak.