Mechanical, materials, and physicochemical effects on the high-temperature tribological behaviour of laser additive manufacturing AlCoCrFeNi2.1 eutectic high-entropy alloys

Abstract

ABSTRACTThe AlCoCrFeNi2.1 eutectic high-entropy alloys (EHEAs) were prepared using selective laser melting (SLM) to study the tribological properties at high temperatures, focusing on the complex mechanism of the friction process. The density of the SLM EHEAs is 99.70%. The lamellar and cellular structures are unevenly distributed at different locations. In situ XRD demonstrated the transition from BCC to FCC with increasing temperature. A large number of B2 particles are distributed in the BCC matrix. The fluctuation of the friction coefficient is closely related to the shape and size of the wear debris. The hardness of the alloy is ∼105 HV at 1000 °C. The wear rate first increases and then decreases with increasing temperature. The maximum thickness of the oxide film is 13.52 μm at 1000 °C and exhibits delamination. The combination of mechanical, materials and physicochemical effects during friction contributes to the excellent high temperature wear resistance.

Keywords

• Eutectic high-entropy alloys
• laser additive manufacturing
• high temperature oxidation
• friction mechanism