TC4时效相变及扩散连接的分子动力学模拟

Molecular dynamics simulation of TC4 aging phase transition and diffusion bonding

摘要:

利用分子动力学方法模拟研究TC4时效相变及扩散连接过程。采用混合势分析了TC4三元合金时效相变过程的径向分布函数以及不同晶体结构相对含量的变化。同时研究了不同保温温度下扩散连接过程的原子浓度分布、扩散连接宽度以及扩散系数。结果表明：在时效相变过程中,TC4结构变化主要表现为亚稳 b 相析出 a 新相,状态稳定后, b 相含量达到23%,与实验结果吻合较好；TC4扩散连接过程中,主要是界面附近的钛原子进行扩散,钒原子扩散能力次之,而铝原子相对较少；相同条件下,扩散连接宽度与保温温度呈现较好线性关系；钛原子扩散系数与保温温度呈指数关系,计算结果与实验相符。

关键词:分子动力学;TC4三元合金;径向分布函数;相变;扩散系数

Abstract:

In the paper, the process of TC4 aging phase transition and diffusion bonding was studied by molecular dynamics method. the radial distribution function of TC4 ternary alloy and the relative content of different crystal structures were analyzed. At the same time, the atomic concentration distribution, diffusion connection width and diffusion coefficient of diffusion bonding process under different thermal insulation temperature are studied. The results show that the structural changes of TC4 in the aging phase transition are mainly manifested in the new a phase of metastable b phase, and the b phase content reaches 23% after the state stabilizes, which is in good agreement with the experimental results. In the process of TC4 diffusion, the titanium atoms near the interface are mainly diffused, and vanadium atomic diffusion is secondary, while aluminum atom is relatively few. Under the same conditions, the diffusion connection width and thermal insulation temperature are in a good linear relationship. The diffusion coefficient of titanium is exponentially related with the temperature of heat preservation, and the results are in accordance with the experiment.

Key words:Molecular dynamics; TC4 ternary alloy; Radial distribution function; Phase change; Diffusion coefficient