Fabrication and microstructure evolution of Al/Mg bimetal using a near-net forming process

The Al/Mg bimetal was fabricated by using the lost-foam casting method that is considered a near-net forming process, and the microstructure evolution of the Al/Mg bimetal from different cross-section locations of the bimetal was investigated in the present work. An obvious interface layer generated in the middle of the aluminum and magnesium, which showed a variation for different cross-section locations of the bimetal. The interface layer at the bottom cross-section location had a maximum thickness, wherein a big gap was observed. The thicknesses of the interface layer gradually decreased from the bottom location to the top location. At the middle cross-section location, the interface layer was uniform and compact. In contrast, the non-uniform interface layer was obtained at the top cross-section location, and the partial location had no the interface layer. The interface layers at the bottom and middle locations consisted of three reaction layers including the Al12Mg17 + delta-Mg, the Al12Mg17 + Mg2Si, and the Al3Mg2 + Mg2Si layers. However, the partial location at the top cross-section location only had the Al12Mg17 + delta-Mg layer.