A nano-sized NbC precipitation strengthened FeCoCrNi high entropy alloy with superior hydrogen embrittlement resistance

Abstract

An equiatomic FeCoCrNi high entropy alloy (HEA) with high strength and excellent hydrogen embrittlement (HE) resistance is manufactured by the precipitation of nano-sized NbC during thermo-mechanical processing. NbC precipitates make the HEA obtain extraordinary mechanical properties via pinning dislocations. With the precipitation strengthening also comes the grain refinement strengthening. Furthermore, the coherent/semi-coherent NbC interfaces are regarded as reversible hydrogen traps based on thermal desorption analysis, thereby increasing the tolerance of HEA to dissolved hydrogen. Despite owning higher strength than the unreinforced one, the precipitation strengthened HEA still manifests superior HE resistance due to NbC preventing hydrogen transport by dislocations.