To reveal the state and effect of oxygen on high entropy alloys (HEAs) prepared by powder metallurgy, a VNbMoTaW refractory HEA was prepared by mechanical alloying and vacuum hot-pressing sintering. During mechanical alloying, with increasing ball milling time, the elemental distribution of the VNbMoTaW powders gradually became homogeneous, and the particle size decreased, while ~0.2 atom% O was introduced. After sintering at 1700 °C and 40 MPa for 2 h, a Ta-rich oxide with a grain size of approximately 15 nm was formed, leading to brittle fracture of the sintered VNbMoTaW HEA. When the sintering temperature was increased to 1900 °C, the grain size of the oxides decreased to ~8 nm and was dispersed on the BCC solid solution matrix. The yield strength of the VNbMoTaW HEA at room temperature and 1600 °C reached 2800 MPa and 350 MPa, respectively, due to Orowan strengthening caused by dispersed nano-sized oxides; additionally, the plasticity deformations at room temperature were ~2%. Although oxygen combined with the constituent metals to form oxides, dispersed nanosized oxides could improve the mechanical properties of HEAs prepared by powder metallurgy. The feasibility of powder metallurgy for HEAs was proven by this work.

为了揭示氧气对粉末冶金制备的高熵合金（HEA）的状态和影响，通过机械合金化和真空热压烧结制备了 VNbMoTaW 难熔 HEA。在机械合金化过程中，随着球磨时间的增加，VNbMoTaW 粉末的元素分布逐渐变得均匀，粒径减小，同时引入了约 0.2 原子％的 O。在 1700 °C 和 40 MPa 下烧结 2 h 后，形成了晶粒尺寸约为 15 nm 的富 Ta 氧化物，导致烧结的 VNbMoTaW HEA 发生脆性断裂。当烧结温度升高到 1900 °C 时，氧化物的晶粒尺寸减小到~8 nm 并分散在 BCC 固溶体基质上。VNbMoTaW HEA 在室温和 1600 °C 下的屈服强度分别达到 2800 MPa 和 350 MPa，由于分散的纳米级氧化物引起的 Orowan 强化；此外，室温下的塑性变形约为 2%。尽管氧与组成金属结合形成氧化物，但分散的纳米级氧化物可以改善粉末冶金制备的 HEA 的机械性能。这项工作证明了粉末冶金用于 HEA 的可行性。