The CrFeCoNi high-entropy alloy (HEA) exhibits excellent mechanical properties at lower temperatures due to its low stacking-fault energy, however, its medium- and high-temperature strengths are still insufficient. In consideration of the potential diversified applications, more strengthening approaches except for the previously proposed L1₂ phase hardening deserve further exploration due to its rapid coarsening tendency at high temperatures. Here, we achieved significant high-temperature strengthening of the cast CrFeCoNi HEA by in-situ precipitation of highly thermostable carbides. Alloys with 0.5 at.% and 1 at.% niobium and carbon were prepared by simple casting processes, i.e. drop cast, solute solution and aging. A highly thermostable microstructure was formed, which comprises very coarse grains accompanied with extensive thermostable carbide precipitates embedded, including submicrometer coherent NbC particles in grain interiors and intergranular coherent M₂₃C₆ carbides. This high thermostability of microstructure, which is beneficial for the high-temperature loading, is ascribed to the synergy of lacking growth driving force and Zenner pinning effect by the carbides. Tensile properties tested at 673, 873 and 1073 K show that the yield strength and ultimate tensile strength are significantly increased by Nb/C doping, along with the elongation escalation at higher temperatures. The strengthening is mainly due to the precipitation hardening of carbide particles.

CrFeCoNi高熵合金（HEA）由于其低的堆垛层错能而在较低的温度下表现出出色的机械性能，但是，其中高温强度仍然不足。考虑到潜在的多样化应用，除了先前提出的L1 ₂以外，还有更多加强方法相变硬化由于其在高温下的快速粗化趋势而值得进一步探索。在这里，我们通过高稳定性碳化物的原位析出实现了CrFeCoNi HEA铸件的显着高温强化。通过简单的铸造工艺（即滴铸，溶质固溶和时效）可以制备出铌和碳含量分别为0.5％和1％的合金。形成了一个高度热稳定的微观结构，包括非常粗糙的晶粒以及大量嵌入的热稳定碳化物沉淀，包括晶粒内部的亚微米相干NbC颗粒和晶间相干M ₂₃ C _6。碳化物。微观结构的这种高热稳定性，有利于高温负荷，归因于碳化物缺乏生长驱动力和齐纳钉扎效应的协同作用。在673、873和1073 K下测试的拉伸性能表明，Nb / C掺杂会显着提高屈服强度和极限抗拉强度，同时高温下的伸长率也会升高。强化主要是由于碳化物颗粒的沉淀硬化。