Atomic Erosion\nBehavior and Influence Mechanism of\n(CoCrFeMn)<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub> High-Entropy Alloy Coating on Fracturing Pump Valves During\nStimulation Operation

The CoCrFeMnNi high-entropy alloy is widely regarded\nas a highly\npromising coating for enhancing the erosion resistance of fracturing\npump valves, owing to its outstanding overall properties. This study\nemploys molecular dynamics simulations to compare and analyze the\nwear and erosion resistance mechanisms of (CoCrFeMn)<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub> coatings with varying\nNi ratios (0.2, 0.4, 0.6, 0.8) under nanoindentation, scratch, and\nimpact conditions at a microscopic scale. The findings indicate that\nas the proportion of Ni increases under the three simulation conditions,\nthe coating exhibits more dislocation locks, an HCP phase structure,\nand shear bands. These factors collectively enhance the material’s\nsurface hardness, wear resistance, and plastic recovery. Nonetheless,\nthis is not universally applicable. When the indentation and scratch\ndepth are greater than 20 Å, the (CoCrFeMn)<sub>0.4</sub>Ni<sub>0.6</sub> coating benefits from robust metal bonds and a stable lattice\nstructure, leading to fewer wear atoms and subsurface defects, thus\nexhibiting superior erosion resistance. These conclusions serve as\na theoretical foundation for the selection of (CoCrFeMn)<sub>1–<i>x</i></sub>Ni<sub><i>x</i></sub> coatings in practical\nfracturing operations.