Yu Xiaoquan, Huang Jiankang, Yang Tao, Fan Ding
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
State Key Laboratory of Advanced Processing and Recycling Non-Ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China.
Materials (Basel). 2022 May 16;15(10):3563. doi: 10.3390/ma15103563.
In this work, the microstructure and growth behavior of Al-Fe intermetallic compounds (IMCs), which formed at interface of weld steel-aluminum joint, are successfully analyzed via the combination of experiment and physical model. A layer IMCs consists of FeAl and FeAl, in which the FeAl is the main compound in the layer. The IMCs layer thickness increases with the increase of the heat input and the maximum thickness of IMCs layer is 22 ± 2 μm. The high vacancy concentration of FeAl IMCs provides the diffusion path for Al atoms to migrate through the IMCs layer for growing towards to steel substrate. By using the calculated temperature profiles as inputs, the combined 2D cellular automata (CA)-Monte Carlo (MC) model is applied to simulate the grain distribution and interfacial morphology evolution at the Al-steel interface. This 2D model simulates the IMCs nucleation, growth, and solute redistribution. The numerical results are in good agreement with the experimental results, suggesting that the growth process can be divided four stages, and the thickness of the FeAl layer increases nonlinearly with the increase of the growth time. The whole nucleation and growth process experienced 1.7~2 s, and the fastest growth rate is 8 μm/s. The addition of Si element will influence diffusion path of Al atom to form different interface morphology. The effects of peak temperature, cooling time, and the thermal gradient on the IMCs thickness are discussed. It shows that the peak temperature has the major influence on the IMCs thickness.
在本工作中，通过实验与物理模型相结合的方式，成功分析了在钢 - 铝焊接接头界面处形成的Al-Fe金属间化合物（IMC）的微观结构和生长行为。一层IMC由FeAl和FeAl组成，其中FeAl是该层中的主要化合物。IMC层的厚度随着热输入的增加而增加，IMC层的最大厚度为22±2μm。FeAl IMC的高空位浓度为Al原子提供了扩散路径，使其能够通过IMC层向钢基体迁移并生长。以计算得到的温度分布作为输入，应用二维元胞自动机（CA） - 蒙特卡罗（MC）组合模型来模拟Al - 钢界面处的晶粒分布和界面形态演变。该二维模型模拟了IMC的形核、生长和溶质再分布。数值结果与实验结果吻合良好，表明生长过程可分为四个阶段，FeAl层的厚度随生长时间的增加呈非线性增加。整个形核和生长过程经历了1.7~2 s，最快生长速率为8μm/s。Si元素的添加会影响Al原子的扩散路径，从而形成不同的界面形态。讨论了峰值温度、冷却时间和热梯度对IMC厚度的影响。结果表明，峰值温度对IMC厚度的影响最大。
