Interface microstructure of aluminum die-casting alloy joints bonded by pulse electric-current bonding process

Aluminum die-casting alloy specimens were bonded by a pulse electric-current bonding (PECB) process using insert alloy powders containing 1 mass% Mg into interface between two bonded specimens. Microstructure of the bonded joints was characterized and analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The results proposed that insert alloy powders containing Mg was an effective technique for solid-state bonding of aluminum alloy specimens containing neither Mg nor other active elements. The reason of the tensile property improvement of the joint bonded by the insert alloy powders was that continuous oxide films originally covered at aluminum alloy surface were broken and removed by reduction reaction of Mg in the inserted alloy powders. This promoted metal–metal contacts, and thereby solid-state bonding of aluminum alloy specimens was facilitated.