First report of agglomerated and sintered carbide-high-entropy alloy composite thermal spray coating

A novel cemented carbide composite coating was developed using high-velocity oxygen fuel (HVOF) spraying with an agglomerated and sintered WC-20 wt.% CoCrFeNi high-entropy alloy (HEA) powder. The coating exhibited a complex microstructure of WC, W 2 C, W, Cr 2 O 3 , spinel oxide, and two FCC phases. CALPHAD simulations provided insights into phase stability but were not fully accurate due to decarburization during deposition. Nano- and micro-indentation revealed hardness variability between the carbide-rich and FCC phases, attributed to decarburization and dissolution mechanisms. The WC-20CoCrFeNi coating demonstrated superior hardness and wear resistance compared to HEAs but did not exceed those of conventional cemented carbide thermal spray coatings. Electrochemical testing revealed enhanced seawater corrosion resistance for the WC-20CoCrFeNi coating than both HEAs and conventional cemented carbides. This study highlights the potential of HEAs as binder materials in cemented carbides processed via agglomeration and sintering, offering a promising balance of properties for engineering applications.