氢在钛晶体中扩散行为的第一性原理

摘要

The first-principles calculation was carried out on the Ti-H supercells based on the density functional theory. The system energy was obtained in various Ti-H supercells. The hydrogen diffusion pathway and the energy barrier were investigated through analyzing the energy change of titanium crystals with the H atom at different positions. The difficulty degree of the hydrogen diffusion was analyzed at the room temperature. The results show that H atoms diffuse across the share surfaces of the octahedral and tetrahedral interstitials and from the octahedral interstitials to the tetrahedral ones in theα-Ti crystals. H atoms diffuse across the adjacent tetrahedral interstitials sharing surfaces and from one tetrahedral interstitial to the other in theβ-Ti crystals. The energy barrier needed to be overcome for the H diffusion in theβ-Ti crystals is lower than that in theα-Ti crystals. H atoms occupying the tetrahedral interstitials in theβ-Ti will play a leading role in theα+β titanium alloy during the diffusion process.%采用基于密度泛函理论的第一性原理计算H原子在Ti晶格中占据不同位置的体系能量。通过对体系能量变化的分析，探求H原子在Ti晶格中的扩散路径和能量势垒，分析室温下H原子在不同Ti晶体结构中的扩散行为与难易程度。结果表明：H原子在α-Ti晶格中从八面体间隙与四面体间隙共用面扩散、迁移，而在β-Ti晶格中则从两相邻四面体间隙共用面扩散、迁移。H原子在β-Ti晶格中扩散迁移所需克服的能量势垒比在α-Ti晶格中扩散迁移所需克服的能量势垒小、更容易进行扩散。在α+β钛合金中，处于β相四面体间隙中的H原子在扩散过程中将起到主导作用。