Microstructure and mechanical properties of W-Ta-V-Cr high-entropy alloy coatings by double glow plasma surface alloying

A W-Ta-V-Cr high entropy alloy (HEA) coating has been successfully synthesized on the tungsten-based surface by Double glow plasma surface alloying (DGPSA) technology. The effects of W-Ta-V-Cr on the microstructure and properties of the coating were systematically investigated. The results illustrated that a compact and homogeneous alloy coating with a thickness of 8.8 μm was formed on the surfaces of pure tungsten. The addition of four elements promoted the formation of BCC phase in the coating, refined the grain size and formed nanocrystalline materials. Thereby the microhardness and abrasion rate of the coating increased and decreased, respectively. The hardness value of the coating reaches 1130 HV, which is 2 times that of the substrate (∼551 HV) and the specific abrasion rate of the coating was only 1/8.5 of that of the W substrate, showing extremely excellent abrasion resistance performance. The coating effectively improves the mechanical of pure tungsten. Such high hardness and abrasion resistant can be attributed to the combined contribution from solid-solution hardening and grain refinement.