:303-30

A single-phase face-centered cubic (fcc) CoCrNi medium-entropy alloy (MEA) with different boron-doping contents (30–1600 ppm) was fabricated by vacuum arc melting, then followed by cold rolling. It was found that the boron-doping in the CoCrNi MEA results in an obvious partial recrystallization and significant refinement of grain size. The tensile yield strength (YS) and ultimate tensile strength (UTS) are 0.94 GPa and 1.17 GPa with the ductility of 26% in 800 ppm boron doping alloy, which was attributed to the strengthening effect of the large unrecrystallized grains. The tensile YS and UTS is dramatically increased up to 1.35 GPa and 1.48 GPa with the ductility of 11% for in 1600 ppm boron doping alloy. In this study, our results demonstrate that the uneven structure can be accomplished effectively by a proper boron addition and the enhancement of mechanical properties is mainly attributed to the unrecrystallized grains microstructure and grain refinement resulting from microalloying with boron by in situ high-energy X-ray diffraction (HE-XRD) technique. This offers a new perspective in interpreting the heterogeneity of structural materials and its influence on mechanical behaviors.