Enhancement of grain boundary carburization of FeCoCrNiMn high-entropy alloy coating by supersonic fine particle bombarding and rare earth

Abstract

A new strategy to simultaneously introduce the supersonic fine particle bombarding (SFPB) and rare earth was proposed in this work. By using the coupling effect of grain refinement and rare earth catalysis, the grain boundary carburization of the FeCoCrNiMn high-entropy alloy (HEA) coating was synergistically enhanced. With increasing content of rare earth, the gray phase of grain boundary was completely strengthened, and the black phase enriched in C increased and refined uniformly. The strengthened coating was composed of FCC phase and M7C3 phase with an orientation relationship of [3, − 1, − 2, − 5] ∥ [1, 1, 0]. Compared with the untreated coating and the single carburized coating, the hardness of the strengthened coating was increased by 1.46 times and 0.33 times, respectively, and the residual compressive stress increased by 31.44 times and 1.80 times, respectively. The research results can provide new methods for strengthening the HEA coatings.