Multipass friction stir welding (FSW) is used to obtain an Al/Cu overlap joint. The microstructure and bonding strength of the Al/Cu joints are analyzed. An overlap joint without defect inside the cross section is obtained when the stir pin interval is 3 mm and the plunge depth is 0.2 mm. The welding of the next pass eliminates the “hook” left on the back side of the upper pass, achieving complete welding over a wide area. The stirring pin peels off the Cu surface layer and moves them into Al matrix. Turbulent interactive structures and exfoliated particle interactive structures are formed. Two obvious intermetallic compound layers are formed on the interface and are identified as the Al₂Cu and Al₄Cu₉ phases. The tensile shear strength of the overlap joints with a stir pin interval of 3 mm reaches an average of 95 MPa, which is approximately equal to that of the 1060Al base metal. Moreover, the copper plate coated with the aluminum layer and the aluminum plate are butt joined by conventional FSW to produce an interface transfer. The thick plate (10 mm) butt joint is welded by transferring the original soft–hard (Al/Cu) interface to the soft–soft (Al/Al) interface.

中文翻译：

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厚板对接过程中多道次摩擦搅拌焊接Al / Cu搭接接头的组织和力学性能及界面转移

多道次摩擦搅拌焊接（FSW）用于获得Al / Cu重叠焊缝。分析了铝/铜接头的组织和结合强度。当搅拌销间隔为3mm且插入深度为0.2mm时，获得了在截面内部没有缺陷的搭接接头。下一道焊缝的焊接消除了上部焊道背面留下的“钩子”，从而实现了大面积的完全焊接。搅拌针将铜表层剥离，并将其移入铝基体中。形成湍流相互作用结构和脱落颗粒相互作用结构。在界面上形成了两个明显的金属间化合物层，分别为Al ₂ Cu和Al ₄ Cu ₉阶段。搅拌销间距为3 mm的搭接接头的拉伸剪切强度平均达到95 MPa，大约等于1060Al母材的平均拉伸强度。而且，涂覆有铝层的铜板和铝板通过常规的FSW对接以产生界面转移。通过将原来的软-硬（Al / Cu）界面转移到软-软（Al / Al）界面来焊接厚板（10毫米）的对接接头。