Optimal wear resistance of particle-reinforced heterostructure high-entropy alloy FeMnCoCr by strength–ductility matching and TRIP effect

Sliding wear results indicated that although the wear rates increased with a decrease in the hardness of the samples, the wear rate of the strength–ductility matching sample with a recrystallization volume fraction of 75 % (V75) abnormally decreased. High strength and low dislocation density in the strength–ductility matching sample were conducive to the formation of the hexagonal close-packed (HCP) phase. However, the high dislocation density in the sample with a low recrystallization volume fraction of 26 % (V26) and the low stress generated during wear testing due to the low strength of the sample with a high recrystallization volume fraction of 87 % (V87) were not conducive to the production of the HCP phase. The thickness of the HCP phase in the subsurface of V75 was 21 μm, which was 2.3 times that of V87 (9 μm) after wear. The generation of the HCP phase not only improved the work-hardening ability of the sample but also led to grain refinement, which was beneficial for acquiring a thicker ultrafine grain layer. The inferior plasticity of V26 and the deformability due to the low strength of V87 were not favorable for the formation of a stable dynamic oxide film. The higher strength resisted deformation, and outstanding ductility reduced the probability of crack generation in V75, which demonstrated a thicker deformation layer and a complete dynamic oxide film after wear, conducive to reducing the wear rate. The proposed bimodal-structural material design strategy provides an effective method for designing materials with high wear resistances.