Low-temperature partial transient liquid phase diffusion bonding of Al/Mg2Si metal matrix composite to AZ91D using Al-based interlayer

Highlights: → AZ91D and Al-Mg2Si MMC are successfully bonded. → Compositional changes and mechanical properties of the bonds depend on heating rate. → Mg2Si, Al12Mg17, Al3Mg2, Al2Mg3 and Al4Mg are the result of the diffusion interaction. -- Abstract: Partial transient liquid phase diffusion bonding of an aluminium metal matrix composite (Al/Mg2Si) to magnesium alloy (AZ91D) was performed using two heating rates. The influence of different heating rates on the microstructure, microhardness and shear strength has been studied. With a decrease in heating rate from 20 to 2 oC/min, the Mg content in the bond line decreased and the microstructure was altered. The composition and microstructure of the joined areas were examined by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDS). It was found that a heating rate of 2 oC/min resulted in an increasing in the shear strength of the joints. The kinetics of the bonding process accelerated due to the increase of solute diffusivity through grain boundaries of the metal matrix composite. Results suggest that Mg and Si contained in the interlayer favours the partial disruption of oxide films, facilitating the bonding process.