Effects of microstructures on the sliding behavior of hot-pressed CoCrMo alloys

Cobalt-chromium-molybdenum (CoCrMo) alloys are widely applied as wear-resistant material. This article aims to illustrate the influence of phase constitution and precipitate morphology on the wear behavior of hot-pressed high carbon alloys. Wear behavior of two kinds of CoCrMo alloys, HP (hot-pressed) and HPA (hot-pressed+annealing) with various microstructure, hardness and surface topography were evaluated in detail. The ε phase dominant HP alloy with homogenous lamellar precipitates demonstrates higher hardness, consequently lower coefficient of friction and prominent wear resistance with mild sliding wear. In contrary, the γ phase dominant HPA alloy with carbide-free grains was characterized by abrasive wear of micro grooves. The matrix hardness strengthened by ε phase is more significant to affect wear behavior than precipitate hardening. Homogenous lamellar precipitates have a stand-out effect to block abrasion and accumulate tribochemical products.