Formation Mechanism Of Welded Joint Of Al/Fe And Al/Cu

With the continuous development of science and technology, a single metal member can not meet the requirements of reducing manufacturing costs, improving economic efficiency in the actual production. Welding components of dissimilar metal were used increasingly. It plays a important role in the development of modern manufacturing industry. The mechanism’s research for the formation of welding joints with dissimilar metals is still less. The understanding of formation mechanism of welding joints of dissimilar metals has a great significance for the adjustment of welding technology. Therefore, this article is on formation mechanism of the Al/Fe,Al/Cu welding joint.In this paper, aluminum/steel and aluminum/copper were welded by electron beam welding,and magnesium alloy/galvanized steel were welded by resistance spot welding,and aluminum/copper were welded by TIG melting brazing welding. Mechanical properties of welded joints of Al/Fe and Al/Cu were analyzed through bond energy and binding energy. Diffusion factor, diffusion activation energy and the vacancy formation energy were used to analyze the element diffusion behavior of the welded joints of Al/Fe and Al/Cu. The welded joint’s formation mechanism of the Al/Fe and Al/Cu were analyzed by the formation enthalpy and effective heat of formation.The results show: The higher of the interfacial average bond energy and the binding energy is, the better of the joint tensile is. The highest point of hardness value is the point of compound with maximum binding energy. The average bond energy and the binding energy of toughness fracture is higher than brittle fracture’s. Al’s diffusion occurs preferentially when Al/Fe were welded. The distance is longer and number of atoms is less for Fe’s diffusion to Al side than Al’s diffusion to Fe side. In the Al/Cu welded joint interface, the degree of enrichment of Al is higher than Cu. The compound of the center of Al/Fe welded joint interface is Fe₂Al₅. The compound of the center of Al/Cu welded joint interface were Al₂ Cu and Al₄Cu₉. Fe₂Al₅ deposited preferentially for the smallest formation enthalpy in the compounds of Al-Fe. Al₂ Cu deposited preferentially for the smallest effective heat of formation in the compounds of Al-Cu,than deposited Al₄Cu₉ according to the formation enthalpy. It provides a theoreticalbasis for mechanical properties and forming mechanism of welded joints of dissimilar materials that using bond energy and binding energy to analyze the mechanical properties of welded joints and using the formation enthalpy and effective heat of formation to analyze the formation mechanism of welded joint of dissimilar materials.