热压Ti/Al界面特性及力学性能的分子动力学模拟

Molecular dynamic simulation of characteristics and mechanical properties of hot-pressed Ti/Al interfaces

采用分子动力学模拟方法研究了600 K、50 MPa下具有特定取向的Ti/Al界面特性及力学性能。通过分析不同时刻下Ti/Al界面原子结构变化、原子浓度分布、径向分布函数(RDF)和均方位移(MSD),研究了热压过程中具有特定取向Ti/Al界面特性,并探讨了不同冷却温度对Ti/Al界面的抗拉强度和变形的影响规律。结果表明,600 K、50 MPa下Ti/Al界面中Al原子的偏离振幅程度大于Ti原子,界面处所设真空层消失,形成过渡层,过渡层厚度随时间的延长逐渐非线性增加。600 K、50 MPa下Ti/Al界面中Ti-Al键长介于Ti-Ti和Al-Al键长之间,Ti原子整体相互作用力(RDF峰值)大于Al原子,Ti原子和Al原子扩散系数分别为2.73×10^(-10)和3.55×10^(-10)m^(2)·s^(-1)。Ti/Al界面的抗拉强度在不同冷却温度下存在显著差异,在300 K以下呈现脆性。随着冷却温度升高,极限抗拉强度下降,在300 K及以上开始发生塑性变形,温度越高,位错形核越早,导致材料塑性增加。拉伸过程中产生的塑性变形及位错主要发生在Al侧,位错类型主要以1/6<112>位错和1/6<110>位错为主,到达极限抗拉强度后在Al侧发生断裂,未发生在Ti/Al界面处,界面处结合良好。

The characteristics and mechanical properties of Ti/Al interfaces with specific orientations at 600 K and 50 MPa were investigated by molecular dynamic simulation method.The characteristics of Ti/Al interfaces with specific orientations during hot pressing were investigated by analyzing the atomic structure variation,atomic concentration distribution,radial distribution function(RDF)and mean square displacement(MSD)of Ti/Al interfaces at different moments,and the effect laws of different cooling temperatures on the tensile strength and deformation of Ti/Al interfaces were explored.The results show that under 600 K,50 MPa,deviation amplitude degree of Al atoms in Ti/Al interfaces is greater than that of Ti atoms,the set vacuum layer at interface disappears to form the transition layer,the thickness of the transition layer gradually nonlinearly increases with the extension of time.Under 600 K and 50 MPa,the bond length of Ti-Al in Ti/Al interfaces is between that of Ti-Ti and Al-Al,the overall interaction force(RDF peak)of Ti atoms is larger than that of Al atoms,and the diffusion coefficients of Ti atoms and Al atoms are 2.73×10^(-10)and 3.55×10^(-10)m^(2)·s^(-1),respectively.The tensile strength of Ti/Al interfaces has significant difference at different cooling temperatures,showing brittleness below 300 K.As the cooling temperature increases,the ultimate tensile strength decreases and plastic deformation starts to occur above 300 K.The higher the temper-ature,the earlier the dislocation nucleation,leading to the increase of plasticity of the material.Plastic deformation and dislocations pro-duced during stretching are mainly concentrated on the Al side,and the types of dislocations are mainly 1/6<112>dislocations and 1/6<110>dislocations,and after reaching the ultimate tensile strength,the dislocations fracture on the Al side,and does not occur at the Ti/Al interfaces where are well bonded.