Liquid-phase diffusion bonding of Al alloy for casting using formate coated insert sheet

Liquid-phase diffusion bonding was performed in air at a bonding temperature of 400 °C, a bonding pressure of 20 MPa, and a heat holding time of 15 min. The specimens for liquid-phase diffusion bonding were AC2C and ADC12, aluminum alloy for casting. After liquid-phase diffusion bonding, solution annealing and aging treatments were also performed on the joints. As a result, the joint strength was improved by about 2 times and the joint efficiency was 90% by using the 3-layer insert material as compared with the Zn single-layer insert material. This was because the Si concentration in the liquid phase decreased by using the 3-layer insert material and Si was discharged to the outer circumference of the joint. By using the 3-layer insert material, the interfacial fracture factor after T6 heat treatment changed from Si particles to Mg oxides.