WC-reinforced AlCoCrFeNi2.1 composite coatings fabricated by laser cladding: Microstructural evolution, mechanical properties and strengthening mechanisms

To enhance the surface mechanical properties of H13 steel, WC-reinforced AlCoCrFeNi 2 . 1 high-entropy alloy (HEA) composite coatings with WC contents ranging from 5 to 30 wt% were fabricated via laser cladding. The coatings formed a robust metallurgical bond with the H13 steel substrate. At a WC content of 30 wt%, thermal stress mismatch between WC and the HEA matrix and the formation of a rigid hard-phase framework led to the initiation of cracks and pores within the coating. WC particles were predominantly distributed near the coating-substrate interface, embedded within blocky and fishbone-like M 6 C carbides. The coatings were composed of FCC, BCC, WC, and M 6 C (Cr 3 W 3 C-type) phases. For coatings with 5–25 wt% WC, partially dissolved granular WC particles were uniformly dispersed in the matrix; at 30 wt% WC, severe particle aggregation occurred, resulting in irregular particle morphology, crack formation, and the precipitation of multiple secondary phases. The coating with 30 wt% WC exhibited a peak microhardness of 554.36 HV 0 . 5 , which was a 31.6% increase relative to the coating with 5 wt% WC. The average friction coefficient decreased to 0.38 at room temperature and 0.43 at 400 °C for the 30 wt% WC coating, indicating significantly enhanced wear resistance. With increasing WC content, the dominant wear mechanism transitioned from adhesive wear to a combination of oxidative wear and abrasive wear. Although all coatings exhibited superior corrosion resistance to the H13 substrate in a 3.5 wt% NaCl aqueous solution, increasing WC content shifted the corrosion potential to more negative values and increased the corrosion current density, leading to a slight deterioration in corrosion resistance.