Evolution in microstructure, properties of the laser cladding CoCrFeMoNi coatings at different annealing temperatures

Laser-cladding CoCrFeMoNi high-entropy alloy coating is composed of face-centred cubic, & sigma; and & mu; phases. After annealing at 700 & DEG;C, many needle-like precipitates of the & sigma; phase are found in the FCC solid solution, and the granular & mu; phase precipitated at the edge of the primary net-structural & sigma; phase. After annealing at 800 & DEG;C, granular & mu; phases are found inside the primary & sigma; phase. The friction coefficients of the coatings (as-cladded, as-annealed at 700 & DEG;C and 800 & DEG;C) decrease dramatically compared with the substrate of H13 steel. Obvious spheroidising of the & sigma; phase at 900 & DEG;C leads to a decrease of hardness and an increase of friction coefficient. Furthermore, the CoCrFeMoNi high-entropy coatings show better corrosion resistance than H13 steel in 3.5 wt-% NaCl solution.