Effect of calcium on intermetallic compound layer at interface of calcium added magnesium–aluminum alloy and titanium joint by friction stir welding

Commercial AMCa602 alloy (Mg–6% Al–2% Ca) and AM60 alloy (Mg–6% Al) were joined to titanium plates by friction stir welding to evaluate the effect of a calcium on the reaction layer at the dissimilar joint interface and the joint tensile strength. At the titanium and AM60 joint interface, a TiAl3 intermetallic compound layer was formed. The thickness of this layer was about 2 μm. A layer containing calcium and a layer containing aluminum and titanium were observed at the titanium and AMCa602 joint interface. The aluminum and titanium layer in the titanium and AMCa602 joint interface was very thin. The content of aluminum in solid-solution in the matrix of AMCa602 was lower than that of AM60 due to the formation of a Ca–Al compound, and this suppressed the formation of TiAl3 at the titanium and AMCa602 joint interface.