High-temperature wear and oxidation resistance of laser clad AlCoCrFeNiMo0.8-TiC composite coatings

Abstract

High-entropy alloys (HEAs) have been extensively studied due to their exceptional high-temperature mechanical properties and wear resistance. Among them, AlCoCrFeNiMo₀.₈-TiC composite coatings exhibit outstanding wear resistance at room temperature, yet their high-temperature behavior remains insufficiently explored. In this study, high-temperature wear and cyclic oxidation tests were conducted at 500 °C, 700 °C, and 900 °C to evaluate the oxidation behavior and tribological performance of these coatings. The oxidation products were primarily TiO₂, Al₂O₃, Cr₂O₃, and Fe₃O₄, with the weight gain following a parabolic trend. The mass increases per unit area were 0.0586, 0.2842, and 1.8112 mg·cm⁻² at 500 °C, 700 °C, and 900 °C, respectively. As temperature increased, the formation of a dense glaze layer from the oxidation products resulted in a continuous reduction in the coefficient of friction (COF). The lowest wear rate was observed at 700 °C (1.5586 × 10⁻⁷ mm³·N⁻¹·m⁻¹), followed by 500 °C (6.2059 × 10⁻⁷ mm³·N⁻¹·m⁻¹). At 900 °C, the glaze layer softened, leading to an increase in wear. Additionally, the dominant wear mechanism transitioned from abrasive wear at lower temperatures to oxidative wear at higher temperatures.