In this study, we examined the microstructure, hydrogen absorption behavior, and native oxide layer of 20Ti–20Zr–20V–20Nb–20Cr high entropy alloy. It was revealed that the alloy consisted of two phases with the chemical composition of 31.1Ti-19.6Zr-16.6V-26.0Nb-6.7Cr (bright phase) and 9.1Ti-20.3Zr-23.4V-14.1Nb-33.1Cr (dark phase). Even though an oxide layer was formed on the surface of the alloy due to the exposure to an air atmosphere for 10 days, it could absorb hydrogen at a low hydrogen pressure without any thermal activation process. After the hydrogen absorption experiment, not only the hydrogen absorption as high as 1.77 wt% was achieved, but the phase transformation occurred; the bright phase transformed to dihydride and the dark one did monohydride. To clarify which phase mainly contributed to the hydrogen absorption behavior, ingots with chemical composition of the dark and bright phases were prepared separately. The hydrogen absorption occurred only for the dark phase ingot, not for the bright phase ingot, suggesting that only the oxide layer on the dark phase seems to have a reactivity with hydrogen. XPS results revealed that while the Cr element was not detected in the oxide film on the bright phase, the oxide film on the dark phase possessed the Cr element. Based on the results, the presence of the Cr element in the oxide would be ascribed to the high reactivity with hydrogen.

在这项研究中，我们研究了20Ti–20Zr–20V–20Nb–20Cr高熵合金的微观结构，氢吸收行为和天然氧化物层。结果表明该合金由化学成分为31.1Ti-19.6Zr-16.6V-26.0Nb-6.7Cr（亮相）和9.1Ti-20.3Zr-23.4V-14.1Nb-33.1Cr（暗）的两相组成相）。即使由于暴露于大气中10天而在合金表面上形成氧化层，它也可以在低氢压下吸收氢而无需任何热活化过程。经过吸氢实验，不仅吸氢量高达1.77 wt％，而且发生了相变。亮相转变为二氢化物，暗相转变为一氢化物。为了弄清楚哪个相主要是导致氢的吸收行为，分别制备了具有暗相和亮相化学成分的硅锭。氢吸收仅发生在暗相晶锭上，而不发生在亮相晶锭上，这表明仅暗相上的氧化物层似乎与氢具有反应性。XPS结果表明，虽然在亮相上的氧化膜中未检测到Cr元素，但在暗相上的氧化膜具有Cr元素。根据结果​​，Cr元素在氧化物中的存在归因于与氢的高反应性。XPS结果表明，虽然在亮相上的氧化膜中未检测到Cr元素，但在暗相上的氧化膜具有Cr元素。根据结果​​，Cr元素在氧化物中的存在归因于与氢的高反应性。XPS结果表明，虽然在亮相的氧化物膜中未检测到Cr元素，但在暗相的氧化物膜中具有Cr元素。根据该结果，氧化物中Cr元素的存在归因于与氢的高反应性。