Ti-Mo互扩散界面吸氢同位素效应的离子束分析研究

为探究Ti-Mo互扩散对金属吸氢的影响，本文采用离子束分析方法对Ti-Mo薄膜的膜-基互扩散界面的吸氢同位素（H和D）效应进行了研究。通过氩离子刻蚀减薄的方法有效降低了表面碳、氧杂质对样品吸氢的影响。吸氢结果表明，对于表面洁净的样品，氢化后固相中氢或氘的浓度均沿着深度随钼原子含量的增加而减小。在单一气体吸氢实验中，氢原子浓度减小的趋势较氘原子缓慢；而在氢氘混合气体吸氢实验中，当容器中的氢氘压强比p(H2)∶p(D2)≥05∶1时，固体中氘氢浓度之比随钼浓度的增加而降低，但当p(H2)∶p(D2)<05∶1时，氘氢浓度之比随钼浓度的增加而升高。因此，由于Ti Mo界面的互扩散，吸氢出现了显著的氢同位素效应，钼的存在不利于体系对氢同位素气体的吸收。

Ion Beam Analysis of Hydrogen Isotope Effect at Ti-Mo Interdiffusion Interface

In order to explore the effect of Ti-Mo interdiffusion on metal hydrogen absorption, hydrogen absorption isotope effects at the Ti Mo alloy due to the interdiffusion at interface were investigated by using ion beam analysis (IBA) which is a non destructive testing method. A Ti film of a few microns was deposited on a Mo substrate using a vacuum evaporation coating method, and interdiffusion layers appeared at the Ti Mo interface. The results indicate that there is a single gradient of elemental Ti or Mo concentration across the interdiffusion layer. Physical phase analyses show that Mo is substituted for Ti and exists as a solid solution. The effect of surface carbon (C) and oxygen (O) impurities on hydrogen (H) and deuterium (D) absorption was reduced by the argon ion sputtering thinning method. The presence of O below the detection limit and a small amount of C on the surface of the sample after sputter thinning have a minimal effect on hydrogen absorption. At the same time, the interdiffusion interface is brought closer to the surface. Hydrogen absorption experiments were carried out in an ultrahigh vacuum device. Both single and mixed absorption experiments for H2 and D2 were conducted, and the samples were analyzed by IBA. The results show that for the samples with clean surfaces, the distribution of hydrogen and deuterium in the solid phase decreases with the increase of molybdenum concentration after absorption of either hydrogen or deuterium gas. This is because that the presence of Mo reduces the bonding ability between the Ti atoms and interstitial H/D atoms, resulting in an increase in the equilibrium pressure of hydrogen/deuterium absorption and a decreased amount of hydrogen absorption. Moreover, the hydrogen concentration tends to decrease more slowly than the deuterium concentration with the increase of depth (i.e. the increase of Mo concentration). When Mo concentration in Ti is greater than 10%, the decrease in lattice constant leads to the reduction of lattice clearance volume. So hydrogen with smaller radius is more likely to occupy the volume gap position, resulting in a sharp drop in the content of larger radius deuterium atoms in the region with high Mo concentration. In mixed hydrogen absorption experiments, the pressure ratio of deuterium to hydrogen (p(H2)∶p(D2)) decreases with the increase of Mo content for p(H2)∶p(D2)≥05∶1, while for p(H2)∶p(D2)<05∶1, the ratio increases with the increase of Mo concentration. In summary, the Ti Mo alloy interdiffusion interface exhibits obvious isotope effects, i.e., hydrogen is more readily absorbed than deuterium. And the presence of Mo is detrimental to the absorption of hydrogen isotope gases in the system. This study not only provides new ideas for hydrogen isotope analysis in metals, but also has important implications for further understanding of matrix atomic diffusion behavior, hydrogen storage materials and improving the performance of metal hydride target materials in use.