Impact Wear Evolution Mechanism of Fe2Ni2CrV0.5Nb0.8 Eutectic High-Entropy Alloy Coating under Dynamic Cyclic Impacts

The dynamic impact test of eutectic high-entropy alloy (EHEA) coating composed of alternating arrangement of soft and hard phases is employed to investigate the damage accumulation principles under impact cycles combined with microstructure characteristic. The Fe₂Ni₂CrV_0.5Nb_0.8 EHEA coating presents a typical hypoeutectic alloys structure with the lamellar eutectic colonies of Laves and FCC phase uniformly dispersed within the primary FCC solid solution matrix. The Laves phase, serving as the primary load-bearing constituent, provides exceptional deformation resistance, while the FCC phase accommodates plastic strain to mitigate stress concentration and suppress crack initiation. The coating undergoes plastic deformation during the initial stage (10–1000 cycles), and the impact wear volume increases slowly. The impact energy dissipation under impact loading is predominantly attributed to elastic–plastic deformation. The slight edge damage stage exceeding 5000 cycles is characterized by oxidative wear. The tangential shear force at the edge position induce material spalling and accelerating impact wear volume growth, progressively elevating energy loss via wear. As the impact cycles approaches 15000, the material exhausts its capacity for further plastic deformation, shifting energy dissipation predominantly to wear-driven mechanisms. The high residual stresses formed on the impact crater surface initiate microcracks, promoting oxide layer exfoliation. Fatigue wear governs the failure mechanism, accompanied by a sharp rise in wear rate due to cyclic stress-induced crack propagation.