Magnesium-lithium alloys are among the lightest commercially-available structural alloys. However, the reactive nature of Mg and Li makes fusion welding of this family of alloys very difficult, if not impossible. The solid-state joining processes are considered suitable alternatives since the joining can be carried out at temperatures well below the melting of these alloys. Refill Friction Stir Spot Welding (Refill FSSW) of 2.2 mm thick Mg-Li plates, using air and argon as the cooling gas, was investigated. Initial examinations revealed formation of adherent oxides-based residues on the tool shoulder. The microstructural examination of the air-cooled samples showed the presence of oxide inclusions within the weldment. As expected, the argon-cooled welding process reduced oxide formation and additionally resulted in flat and smooth welded surfaces. Nevertheless, and somehow unexpectedly, the presence of oxide inclusions in the air-cooled samples had no noticeable effect on the shear strength or microhardness of the joints.

镁锂合金是最轻的市售结构合金之一。但是，Mg和Li的反应性使该族合金的熔焊非常困难，即使不是不可能的。固态连接工艺被认为是合适的替代方法，因为该连接可以在远低于这些合金的熔融温度下进行。研究了使用空气和氩气作为冷却气体的2.2毫米厚Mg-Li板的补充摩擦搅拌点焊（Refill FSSW）。初步检查发现在刀肩上形成了粘附的基于氧化物的残留物。空气冷却样品的显微结构检查表明，焊件中存在氧化物夹杂物。正如预期的那样，氩气冷却的焊接工艺减少了氧化物的形成，并另外获得了平整，光滑的焊接表面。