(1. 南京航空航天大學(xué)材料科學(xué)與技術(shù)學(xué)院，南京 210016；
2. 中航工業(yè)金城南京機(jī)電液壓工程研究中心，南京 211106)
摘 要: 采用基于密度泛函理論的第一性原理計算H原子在Ti晶格中占據(jù)不同位置的體系能量。通過對體系能量變化的分析，探求H原子在Ti晶格中的擴(kuò)散路徑和能量勢壘，分析室溫下H原子在不同Ti晶體結(jié)構(gòu)中的擴(kuò)散行為與難易程度。結(jié)果表明：H原子在α-Ti晶格中從八面體間隙與四面體間隙共用面擴(kuò)散、遷移，而在β-Ti晶格中則從兩相鄰四面體間隙共用面擴(kuò)散、遷移。H原子在β-Ti晶格中擴(kuò)散遷移所需克服的能量勢壘比在α-Ti晶格中擴(kuò)散遷移所需克服的能量勢壘小、更容易進(jìn)行擴(kuò)散。在α+β鈦合金中，處于β相四面體間隙中的H原子在擴(kuò)散過程中將起到主導(dǎo)作用。
關(guān)鍵字: Ti晶體；H原子擴(kuò)散；第一性原理；體系能量；間隙
（1. College of Materials Science and Technology,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. Aviation Industry Corporation of China Jincheng Nanjing Electrical and
Hydraulic Engineering Research Center, Nanjing 211106, China）
Abstract: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 the α-Ti crystals. H atoms diffuse across the adjacent tetrahedral interstitials sharing surfaces and from one tetrahedral interstitial to the other in the β-Ti crystals. The energy barrier needed to be overcome for the H diffusion in the β-Ti crystals is lower than that in the α-Ti crystals. H atoms occupying the tetrahedral interstitials in the β-Ti will play a leading role in the α+β titanium alloy during the diffusion process.
Key words: Ti crystal; H atom diffusion; first-principles; system energy; interstitials
