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

Abstract

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.

Keywords:

• Al alloy
• liquid phase diffusion bonding
• formic acid
• bond strength
• microstructure

Acknowledgment

We would like to thank Mr. Norio Inami of Toyota Motor Corporation for his great help in proposing experimental methods and organizing experimental data. We express our gratitude and deepest appreciation.