Effect of WC on the microstructure and mechanical properties of laser-clad AlCoCrFeNi2.1 eutectic high-entropy alloy composite coatings

AlCoCrFeNi2.1/WC eutectic high-entropy alloy composite coatings were prepared on a 316 L stainless steel substrate via the laser cladding method. The effects of the WC content on the phase composition, microstructure, and mechanical properties of the composite coatings were investigated. The results revealed that the laser-clad AlCoCrFeNi2.1/WC eutectic high-entropy alloy composite coating mainly consisted of FCC and BCC phases. As the WC content increased from 0 wt% to 30 % wt%, the Cr7C3 and Cr21W2C6 phases were gradually precipitated from the composite coating. Consequently, the microhardness of the composite coating increased from 318.6 to 572.3 HV1.0. The strengthening mechanism of composite coatings mainly comprised solid solution strengthening, second-phase strengthening, and fine-grain strengthening. Additionally, the high dislocation density, caused by rapid condensation during the laser cladding process, contributed to the improvement in the coating hardness. Wear experiments revealed a significant improvement in the wear resistance of the composite coating with increasing WC content. The composite coating with 30 wt% WC exhibited the highest hardness and wear resistance with an average friction coefficient of 0.535, as well as a wear rate and wear volume loss of 4.4 x 10-7 mm3N-1 mm-1 and 5.44 mm3, respectively.