Zr/Nb nanoscale multilayer coatings (NMCs) were studied after hydrogenation in a gaseous environment at 400 °C. The hydrogen distribution and content were determined by pressure and hydrogenation time. Increasing the pressure from 0.2 to 2 MPa resulted in different hydrogen distribution within the Zr/Nb NMCs, while the concentration remained constant at 0.0150 ± 0.0015 wt. %. The hydrogen concentration increased from 0.0165 ± 0.001 to 0.0370 ± 0.0015 wt. % when the hydrogenation time was extended from 1 to 7 h. The δ-ZrH hydride phase was formed in the Zr layers with Zr crystals reorienting towards the [100] direction. The Nb(110) diffraction reflex shifted towards smaller angles and the interplanar distance in the niobium layers increased, indicating significant lateral compressive stresses. Despite an increase in pressure, the nanohardness and Young’s modulus of the Zr/Nb NMCs remained stable. Increasing the hydrogen concentration to 0.0370 ± 0.0015 wt. % resulted in a 40% increase in nanohardness. At this concentration, the relative values of the Doppler broadening variable energy positron annihilation spectroscopy (S/S0) increased above the initial level, indicating an increase in excess free volume due to hydrogen-induced defects and changes. However, the predominant positron capture center remained intact. The Zr/Nb NMCs with hydrogen content ranging from 0.0150 ± 0.0015 to 0.0180 ± 0.001 wt. % exhibited a decrease in the free volume probed by positrons, as demonstrated by the Doppler broadening variable energy positron annihilation spectroscopy. This was evidenced by opposite changes in S and W (S↓W↑). The microstructural changes are attributed to defect annihilation during hydrogen accumulation near interfaces with the formation of hydrogen–vacancy clusters and hydrides.

中文翻译：

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Zr/Nb 纳米多层结构中氢引起的微观结构变化

在 400 °C 的气体环境中氢化后研究了 Zr/Nb 纳米级多层涂层 (NMC)。氢气的分布和含量由压力和氢化时间决定。将压力从 0.2 MPa 增加到 2 MPa 会导致 Zr/Nb NMC 内的氢分布不同，而浓度保持恒定在 0.0150 ± 0.0015 wt。 %。氢浓度从 0.0165 ± 0.001 增加到 0.0370 ± 0.0015 wt。当氢化时间从1小时延长至7小时时，百分比增加。在 Zr 层中形成 δ-ZrH 氢化物相，Zr 晶体重新取向为 [100] 方向。 Nb(110) 衍射反射向更小的角度移动，并且铌层中的晶面距离增加，表明显着的侧向压应力。尽管压力增加，Zr/Nb NMC 的纳米硬度和杨氏模量仍保持稳定。将氢气浓度增加至 0.0370 ± 0.0015 wt. % 导致纳米硬度增加 40%。在此浓度下，多普勒展宽变能量正电子湮没光谱（S/S0）的相对值增加到初始水平以上，表明由于氢引起的缺陷和变化而导致过量自由体积的增加。然而，主要的正电子捕获中心仍然完好无损。 Zr/Nb NMCs 的氢含量范围为 0.0150 ± 0.0015 至 0.0180 ± 0.001 wt。正如多普勒展宽可变能量正电子湮没光谱所证明的那样，％表现出正电子探测到的自由体积的减少。 S 和 W 的相反变化（S↓W↑）证明了这一点。微观结构的变化归因于氢在界面附近积累过程中的缺陷湮灭以及氢空位簇和氢化物的形成。