A multiple nonmetallic atoms co-doped CrMoNbWTi refractory high-entropy alloy with ultra-high strength and hardness

A multiple nonmetallic atoms co-doped CrMoNbWTi refractory high-entropy alloy (RHEA) was prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The as-sintered RHEA co-doped with C, N, and O exhibited ultra-high strength and hardness of 4345 MPa and 11.88 GPa, respectively. The microstructural observations indicated that both N and O were completely reacted with the refractory metallic elements to in-situ generate massive dispersed refractory compounds of (Nb,Ti)N and Ti2O3, while C was mainly dissolved in the BCC solid-solution phase. The strengthening mechanisms of the multiple nonmetallic atoms (C, N, and O) were discussed in this paper. The results demonstrated that the excellent mechanical properties were not only attributed to the traditional solid solution, grain boundary, Orowan strengthening mechanisms, but also to the additional C interstitial strengthening and dispersed refractory compounds of (Nb,Ti)N and Ti2O3.