By using of the eutectic reaction of siver and aluminum, short Al₂O₃ fiber reinforced Al composite(Al₂O₃/Al FRM) was diffusion-brazed in vacuum at 853K with 0.1mm or 0.01mm thick silver foil as interlayer. Effects of melting of the FRM matrix by the interlayer, discharge of the liquid from the joint area by joining pressure, and diffusion of the liquid into the matrix on the structure and strength of joint were investigated.
With the joining time increasing, the residue of interlayer decreased and the joint strength increased. However, after the solidification of joint area, the fiber segregation occured at the center of joint and the strength of joint decreased. Higher strength of joint was got with intermittent residue of melted reaction layer existing in the joints. Higher joining pressure discharged the melted interlayer out of joints, which would make the fiber segregate in the joint, and the strength of joint became lower than that made with lower joining pressure. Al₂O₃/Al FRM joints fabricated with 0.01mm silver foil had only a very low strength because during heating period the silver interlayer diffused into base metal and the amount of liquid in joints were not enough to remove the oxide film off the surface to be joined.