Microstructure and wear resistance of the heat-treated eutectic high-entropy alloy Al0.3CoCrFeNiMo0.75 produced by spark plasma sintering and high-speed laser metal deposition

High-entropy alloys (HEAs) have already proven as a promising research approach in surface technology. Within the group of HEAs, eutectic high-entropy alloys (EHEAs) with their fine lamellar structure are characterized by high wear and corrosion resistance. Therefore, EHEAs are suitable candidates for surface protection applications under complex conditions. In the present study, EHEA Al_0.3CoCrFeNiMo_0.75 coatings were deposited using high-speed laser metal deposition (HS-LMD). In contrast, dense bulk alloys were realized powder metallurgical by spark plasma sintering (SPS). A heat treatment at 1100 °C for 12 h is conducted to determine the alloy's resistance to softening. High cooling rates during HS-LMD resulted in the formation of an ultrafine eutectic structure, whereas heat treatment coarsened the lamellar structure of the SPS bulk alloy and HS-LMD coating. A hardness decrease by microstructure coarsening was detected. Furthermore, wear tests were carried out under different wear conditions. Detailed characterization of the phase formation and wear properties of all production routes in the untreated, and heat-treated states enable a better understanding of the microstructural effects in the EHEA Al_0.3CoCrFeNiMo_0.75.