Dry abrasive wear and solid particle erosion assessments of high entropy alloy coatings fabricated by cold spraying

Abstract

Recent advances in advanced metallic alloys have enabled the development of high entropy alloys (HEAs) for extreme engineering environments. HEAs are characterized by their mixing of elements with equimolar concentrations or near to equimolar concentrations, which enables the formation of solid-solution structures due to inherent high configurational entropy. With the advancement of HEAs, the attractiveness of these alloys as cold-sprayed coatings for wear resistant surfaces has been increasing. In the present study, a low-pressure cold spraying technique was employed to fabricate two new mechanically alloyed AlCoCrFeMoW and AlCoCrFeMoV HEA coatings. The phase formations, microstructure evolutions, and average microhardness of the fabricated HEA coatings were systematically investigated, in order to assess their resistance to dry abrasive wear and solid-particle erosion. The results showed that the cold-sprayed HEA coatings exhibited refined microstructure and low porosity, with the presence of body-centered cubic (BCC1 and BCC2) structures and CrMo intermetallic phases. Microhardness results revealed that AlCoCrFeMoV HEA coatings achieved the highest average hardness of around 561±63HV, such that it was 35% and 52% higher than that of AlCoCrFeMoW and AlCoCrFeMo HEA coatings, respectively. Dry abrasive wear results showed lower wear rates were achieved for AlCoCrFeMoV HEA coatings (590×10−6mm3/Nm), followed by AlCoCrFeMoW (660×10−6mm3/Nm) and AlCoCrFeMo HEA coatings (720×10−6mm3/Nm). However, damage during solid particle erosion was found to be higher in case of AlCoCrFeMoV HEA coatings compared to the other two coatings, suggesting no apparent correlation with microhardness values. These results suggest that the existence of high weight fractions of solid-solution phases in conjunction with refined microstructure and low porosity resulted in improved resistance to abrasive loading for the AlCoCrFeMoV HEA coatings but undermine performance and resistance to solid particle erosion damage.