Interstitial oxygen (O) is one of the most critical impurity elements for titanium (Ti) and its alloys. This study adopts the first-principles method based on the density function theory (DFT) to calculate the lattice constants, elastic properties and electronic structures of the pure Ti and Ti-O(O) structures with different O contents. Results show that the c/a lattice parameter increases with the increase of O content and reaches the maximum value of 1.642 when O content is 20 at%. In addition, the bulk modulus (B), shear modulus (G) and G/B of the Ti-O(O) structures gradually increase with the increase of O content, and the corresponding ductility becomes worse. Furthermore, interstitial O atom makes a uniform transformation of the metal bond shift toward a more covalent direction, which strongly influences the ductility of Ti-O(O) structures. Furthermore, the interstitial O leads to the great difference in the chemical bond behavior of the crystals in different directions, which shows anisotropy on the micro level. The aim of this study is to reveal the effect of interstitial O on the mechanical properties of Ti alloys, and also to provide reference for reasonable control of O content of Ti alloys in industrial production.

中文翻译：

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间隙氧对α-Ti强度/延展性影响的第一性原理研究：晶体结构、弹性性能和电子结构


间隙氧（O）是钛（Ti）及其合金最关键的杂质元素之一。本研究采用基于密度函数理论（DFT）的第一性原理方法计算了纯Ti和不同O含量的Ti-O(O)结构的晶格常数、弹性性能和电子结构。结果表明，c/a晶格参数随着O含量的增加而增大，当O含量为20 at%时，c/a晶格参数达到最大值1.642。此外，随着O含量的增加，Ti-O(O)结构的体积模量(B)、剪切模量(G)和G/B逐渐增大，相应的延展性变差。此外，间隙O原子使金属键均匀转变向共价方向移动，这强烈影响Ti-O(O)结构的延展性。此外，间隙O导致不同方向晶体的化学键行为存在很大差异，在微观水平上表现出各向异性。本研究旨在揭示间隙O对钛合金力学性能的影响，为工业生产中合理控制钛合金O含量提供参考。