The 1-mm-thick Al to Cu friction stir welding is successfully performed at the tool offsets toward Al side ranging from 0 to 2 mm. With increasing tool offset, the phenomenon of material sticking to tool shoulder surface is restricted and the area of Al–Cu mixing zone is reduced progressively. As the tool offset is increased from 0 to 1 mm, the weld shows a variation of intermetallic phases from CuAl₂ + Cu₉Al₄ to CuAl₂ and exhibits a lowering in hardness and tensile properties. The 2-mm-offset weld without intermetallic phases discernible exhibits the highest hardness due to the thinness of Cu lamellar and Al-rich compound layers, and the joint featured by a failure at the relatively soft region adjacent to harder Al–Cu mixing zone in a ductile pattern shows the best tensile strength equivalent to 80% of that of the base material.

1毫米厚的Al到Cu摩擦搅拌焊接成功地在朝Al侧偏移0到2 mm的范围内进行。随着刀具偏移的增加，材料粘附在刀肩表面的现象受到限制，Al-Cu混合区的面积逐渐减小。随着刀具偏移量从0毫米增加到1毫米，焊缝显示出金属间相从CuAl ₂  + Cu ₉ Al ₄到CuAl _{2的变化。}并且表现出硬度和拉伸性能的降低。由于铜片层和富铝化合物层的厚度薄，没有金属间相的2毫米偏移焊接表现出最高的硬度，并且接头的特征是在较硬的Al-Cu混合区附近的相对较软的区域失效延展性图案显示出最佳拉伸强度，相当于基材的80％。