Effect of tungsten and vanadium additions on the dry abrasive wear and solid particle erosion of flame-sprayed AlCoCrFeMo high entropy alloy coatings

Equiatomic AlCoCrFeMoW and AlCoCrFeMoV HEA compositions were fabricated using a cost-effective flame spraying technology. The microstructure, phases, average microhardness, and nano hardness of the fabricated HEA coatings were systematically investigated, in order to assess their resistance to dry abrasive wear (ASTM G65 Standard) and solid-particle erosion (ASTM G76 Standard). Furthermore, linear regression analysis was performed to assess the relationship between the variables based on microhardness, hardness to elastic modulus (H/E) ratio, and strain hardening coefficient (alpha) in order to describe the coating's performance under abrasive wear and solid particle erosion. The results showed the formation of BCC1 and BCC2 phases coupled with mixed oxide inclusions for the AlCoCrFeMoW HEA coatings, whilst FCC and spinel-type oxides were observed in the AlCoCrFeMoV HEA coatings. Owing to differences in phase formations, the average microhardness as well as the average nanohardness were 18% and 46% higher, respectively, for the AlCoCrFeMoV HEA coatings than those of the AlCoCrFeMoW HEA coatings. Performance assessment under dry abrasive wear indicated that lower wear rates (210 x 10-6 mm3/Nm) were achieved for the AlCoCrFeMoV HEA coatings, which showed moderate to strong correlation with microhardness and strain hardening coefficient. In terms of solid particle erosion, lower erosion rates (i.e., 0.51 mm3/g for 300 and 0.65 mm3/g for 900) were achieved for the AlCoCrFeMo HEA coatings, followed by AlCoCrFeMoW and AlCoCrFeMoV HEA coatings, which are in good agreement with the H/ E values. These results indicate the efficacy of flame-sprayed HEA coatings under demanding environments, which can be potentially transformative for addressing different tribological features for industrial component protection.