V元素对β型钛合金力学性能与电子结构的影响

Effect of V on Mechanical Properties and Electronic Structure of β-Type Titanium Alloys

摘要:

以β-Ti为研究对象，采用基于密度泛函理论的第一性原理计算的方法，用V原子取代Ti原子构建不同V含量的Ti-V系模型，对其力学性能及电子结构进行计算。计算结果表明：V原子的添加会降低β-Ti的弹性常数和弹性模量，并提升体系的塑韧性，这是由于在形成Ti-V体系时，两种原子均失去电子，体系的电子活跃程度增加，类金属键的键性增强，塑韧性得到提升。此外Ti和V原子的3d轨道主要参与成键，这是导致塑韧性提升的关键原因。同时还有部分电子聚集在两种原子周围，且具备一定的方向性，说明体系内部也有共价键存在，共价键的存在是提升体系机械稳定性的关键所在。

Abstract:

Taking β-Ti as the research object, the first-principles calculations based on density functional theory were performed to construct a model of Ti-V system with different V contents by substituting Ti atoms with V atoms and to calculate the mechanical properties and electronic structures. The calculation results indicate that the addition of V atoms decreases the elastic constant and elastic modulus of β-Ti and improves the plasticity and toughness of the system. This is because during the formation of the Ti-V system, both atoms lose electrons. Therefore, the electronic mobility of the system increases, the bonding strength of the metallic bond is enhanced, and the plasticity and toughness of the system are improved. In addition, the 3d-orbitals of Ti and V atoms are mainly involved in bonding, which is the key reason for the improvement of plasticity and toughness. Meanwhile, there are also some electrons with directivity gathered around the two atoms, which indicates that there is also a covalent bond within the system. The existence of covalent bond is the key to enhancing the mechanical stability of the system.