铝/钢焊接接头界面Fe2Al5生长模拟研究

Growth simulation study on Fe2Al5 in the interface of aluminum-steel joints

基于蒙特卡罗随机模型,模拟铝钢焊接接头界面金属间化合物Fe2Al5的生长过程。针对Fe2Al5的特殊晶体结构,通过随机选定Fe2Al5的 c 轴方向与形核界面的夹角来确定晶粒生长取向,以实际焊接过程的热循环作为模型的温度参考,采用局部抽象的网格之间的结合能的变化作为生长驱动力来建立模型。模拟结果表明,不同形核取向下的晶粒生长存在明显的竞争生长现象,而夹角为90°的晶粒生长竞争优势明显,使界面上生长的Fe2Al5呈现“板条状”分布,导致这一现象的根本影响因素为Fe,Al原子在Fe2Al5晶粒中的扩散机制不同,这与实际的试验结果非常符合。

The growth process of intermetallic compounds Fe2Al5in the interface of aluminum-steel joints was simulated based on the stochastic model of Monte Carlo. Because of the special crystal structure of Fe2Al5, the angle between the c -axis oriented and nucleation-interface was selected randomly to determine growth orientation. Thermal cycling of actual welding process was used as the temperature of model, and the local abstract bonding energy changing was used as the driving force for crystal growth. The simulation results show that the crystal growth existed obvious competitive advantage with the different nucleation orientation of crystal, and then the competitive was most obvious when the angle between the c -axis oriented and nucleation-interface was 90°. Thus, Fe2Al5intermetallic compounds layer was present and it was tongue-like distributed. The fundamental influencing factor of this phenomenon is the different diffusion mechanism of Fe and Al atoms in Fe2Al5grains. The simulation results were in agreement with the experimental results.