Tribocorrosion performance of laser additively processed high-entropy alloy coatings on aluminum

Al–Co–Cr–Fe high-entropy alloy coatings were laser additively produced on aluminum substrate under different laser fluences (17.0–21.2 J/mm2). The resultant coatings consisted of a mixture of high-entropy and intermetallic phases, which resulted in marked improvement in hardness (~ 275–500 HV) as compared to the aluminum substrate (~ 30 HV). Coating corresponding to higher laser fluences showed lower corrosion currents (Icorr ~ 3.6 × 10−4 mA/cm2) and higher linear polarization resistance (LPR) of ~ 14–16 kΩ/cm2 as compared to the aluminum substrate (Icorr ~ 7×10−4 mA/cm2) and ~ 11 kΩ/cm2 in 0.6 M NaCl solution. The behavior of surface properties was analyzed in relation to the variation in fraction of HEA and intermetallic phases within the coatings resulting due to increased content of Al from the Al substrate with an increase in the laser fluence. The coating consisting of optimal amount of HEA and intermetallic phases showed a tenfold decrease wear volume loss (0.01 mm3) as compared to Al substrate showing 0.11 mm3.