Oxygen-induced lattice distortion in beta-Ti3Nb and its suppression effect on beta to alpha" transformation

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讲座内容：

We report a first-principles density functional theory study on the interaction of interstitial O atoms in body-centered cubic beta-Ti3Nb alloy, the lattice distortion induced by O and its effect on the beta to alpha" transformation. Our calculations demonstrate strong repulsion between O atoms in general, but also reveal a weak attraction at an O-O separation of around 5.63 Å (√3a), which corresponds to a Ti6Nb2O structure. At low concentration (Ti96Nb32O), O induces a local alpha"-like structure in beta-Ti3Nb lattice, albeit to the extent of the nearest- and next-nearest neighbors, and exerts either a remarkable (6-8 meV atom-1) or a negligible (0-1 meV atom-1) energy barrier to the beta to alpha" transformation, dependent on the orientation of its elastic dipole with respect to the external stress. At high concentration (Ti6Nb2O), interstitial O atoms give rise to the shuffling of neighboring {110} planes along the <110> direction and generate a semi-alpha" structure, which is believed to be the nanodomain structure observed in experiment by Miyazaki and co-workers. In both cases, O brings up suppression effect on the beta to alpha" transformation.

主讲人介绍：

耿文通，北京科技大学材料科学与工程学院教授、博士生导师，主要以基于密度泛函理论的量子力学第一原理计算为手段，研究金属材料和无机非金属材料的力学、电学、磁学、及输运性质等。耿文通教授1992年、1995年于兰州大学物理系理论物理专业获学士、硕士学位；1998年在中国科学院物理研究所获博士学位；1998－2005年，先后在美国西北大学、德国Fritz-Haber研究所等地从事博士后研究工作。发表论文约60篇，被国际同行引用1000余次。

发布时间：2015-05-20 15:14:01