Investigation of friction and wear performance of laser additively manufactured AlCrFeNiMo high entropy alloy coating at temperatures from RT to 900 °C

In this study, AlCrFeNiMo high-entropy alloy (HEA) coatings have been successfully fabricated by laser cladding method using the mixed elemental powders as the raw material. Two different laser powers (200 W for HEA1 and 350 W for HEA2) were used, aiming to investigate the influence of processing parameters on the phase constitution, microstructure and properties of as-cladded HEA coatings. It has been found that both AlCrFeNiMo HEA coating is consisted of BCC1, BCC2 and Mo-rich phases. HEA2 exhibited finer microstructure, reduced elemental segregation, and slightly higher hardness (833.3 HV) compared to HEA1 (808.6 HV). Tribological testing from room temperature to 900 °C showed that HEA2 consistently achieved lower friction coefficients and wear rates with lowest values of 0.29 and 0.68 × 10 −5 mm 3 /Nm at 900 °C, respectively. Cross-sectional and surface analyses revealed a transition from abrasive wear at room temperature to oxidative wear at 900 °C, with HEA2 forming a denser, stable tribo-oxide layer enriched in Al and Cr. These results highlight that optimizing laser processing enhances the microstructural integrity and high-temperature wear resistance of AlCrFeNiMo HEA coatings, making them promising for extreme service conditions. • AlCrFeNiMo high entropy alloy coatings were successfully fabricated by laser cladding under varying processing conditions. • BCC1, BCC2, and minor Mo-rich phases were identified, with enhanced phase homogeneity at higher coating energy. • HEA2 exhibited higher hardness and superior tribological performance across temperatures from RT to 900 °C. • A transition from abrasive to oxidative wear mechanisms was observed with increasing temperature. • Cr 2 O 3 - and Al 2 O 3 -rich tribo-oxide sublayers formed at 900 o C, improving wear resistance and friction stability.