Impressive Thermal Oxidation Resistance and Wear Properties of Nano-Ceo2/Fecrnimnal High Entropy Composite Coating with B2 Precipitates

Abstract

This study has further characterized the microstructure and phase composition of FeCrNiMnAl/CeO2 HEA composite coatings. Nano-CeO2 particles could influence the texture structure, promoting equiaxed grain growth and disrupting columnar grain growth by aiding nucleation. Due to Marangoni flow, uneven distribution of nano-CeO2 particles was observed, leading to differences in grain size across different regions. Microstructure analysis revealed a dual-phase BCC structure with B2 ellipsoidal precipitates, contributing to improved mechanical properties and high-temperature performance due to reduced lattice mismatch. As the temperature increased (400-800°C), the high temperature oxidation reactions became more prominent. The high-temperature oxidation behavior of the HEA composite coating and the substrate under 800°C for 100 h was revealed. The diffusion depth of oxygen in the HEA composite coating was only 25.56 μm, while the oxide layer thickness of substrate reached 442.25 μm. With increasing high-temperature oxidation time, significant coarsening of the ordered BCC B2 phase occurred in the HEA composite coating. The kinetics of coarsening could be described as r2 – r02 = kt. High-temperature friction behavior showed significant three-body wear with temperature, accompanied by decreasing COFs and wear rate. Our study offers insights into the mechanical properties of FeCrNiMnAl/CeO2 HEA coatings under high temperatures, with COFs minimized at 700°C (0.27285) and the wear rate at the lowest at 800°C (3.005 × 105 mm3/N·m).

Keywords: High entropy alloy, B2 precipitate, Laser cladding, Oxidation resistance, Wear.