An equiatomic CoCrNi medium entropy alloy (MEA) with face-centered cubic (FCC) structure exhibits excellent combination of strength and ductility. Here we employ interstitial doping to enhance its mechanical performance. Interstitial CoCrNi MEAs with two different carbon contents, i.e., 0.5 at. % and 1 at. %, as well as a carbon-free CoCrNi reference MEA have been studied. The results show that up to 1 at. % carbon can be fully dissolved into the homogenized plus water-quenched FCC solid solution structure. Subsequent annealing leads to precipitation of nano-sized M₂₃C₆ type carbides which provide dispersion strengthening and enhanced strain hardening. The best combination of ultimate tensile strength of 1180 MPa at an elongation above 60% was obtained in fine grained CoCrNi doped with 0.5 at. % of carbon. Carbon alloying is also shown to significantly increase the lattice friction stress. Dislocation glide and mechanical twinning act as main deformation mechanisms. Thus, the joint contribution of multiple deformation mechanisms in the carbon-doped MEAs leads to significantly enhanced strength-ductility combinations compared to the carbon-free reference alloy, demonstrating that interstitial alloying can enhance the mechanical properties of MEAs.

具有面心立方（FCC）结构的等原子CoCrNi中熵合金（MEA）具有出色的强度和延展性。在这里，我们采用间隙掺杂来增强其机械性能。具有两种不同碳含量（即0.5 at。％）的间隙CoCrNi MEA。％和1 at。％，以及无碳的CoCrNi参考MEA进行了研究。结果显示高达1 at。％的碳可以完全溶解到均质加水淬FCC固溶体结构中。随后的退火导致纳米级M ₂₃ C _6的沉淀型碳化物，可提供弥散强化和增强的应变硬化。在掺有0.5 at的CoCrNi细晶粒中，在60％以上的伸长率下获得了1180 MPa的极限抗拉强度的最佳组合。碳百分比。碳合金化还显示出显着增加晶格摩擦应力。位错滑行和机械孪生是主要的变形机制。因此，与不含碳的参比合金相比，碳掺杂的MEA中多种变形机制的共同作用导致强度-延展性组合得到显着增强，这表明间隙合金化可以增强MEA的机械性能。