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镁/钛(Mg/Ti)异种金属既不反应也不互溶的特性制约着两者之间的冶金结合和可靠连接。为解决这一问题并拓宽Mg、Ti的应用,采用富铝镁基焊丝对Mg/Ti实施激光填丝搭接焊,实现了Mg/Ti之间的连接。在此基础上,利用扫描电镜对界面进行观察分析,并利用Miedema二元热力学模型和Toop三元热力学模型对调控元素Al在界面处的扩散及连接机理进行研究。结果表明,在焊丝中调控元素Al的参与下,Mg/Ti界面处形成超薄的反应层,元素线扫描结果显示Al在靠近Ti一侧界面处富集,实现了界面的冶金结合。热力学计算结果显示,在界面处Al-Ti化合物具有更大的析出驱动力,而且Al在富Ti一侧的化学势较低,且Al的界面偏聚导致Al的化学势进一步下降,表明Al的扩散方式为上坡扩散。
Magnesium / titanium (Mg / Ti) dissimilar metals neither reaction nor mutual solubility of the constraints between the two metallurgical bonding and reliable connection. In order to solve this problem and broaden the application of Mg and Ti, Mg-Ti-based Mg-Ti-based Al-rich Mg-Ti welding wire was used for lap welding. On this basis, the interface was observed and analyzed by SEM, and the diffusion and connection mechanism of Al at the interface were studied by Miedema binary thermodynamic model and Toop ternary thermodynamic model. The results show that the ultrathin reaction layer is formed at the interface of Mg / Ti with the help of the control element Al in the wire, and the elemental line scan results show that Al is enriched near the interface of the Ti side to achieve metallurgical bonding at the interface. The results of thermodynamic calculations show that the Al-Ti compound has a larger precipitation driving force at the interface, and the chemical potential of Al is lower at the side rich in Ti, and the segregation of Al causes the chemical potential of Al to decrease further, indicating that Al Diffusion is uphill proliferation.