1990 Volume 8 Issue 3 Pages 336-342
Liquid phase diffusion bonding in which a liquid phase is formed by the reaction diffusion between insert and base metals has been studied. Ag was adopted as the insert metal and Cu was used as the base metal for simplicity. The growth process of the liquid phase along the laying surface was investigated. Bonding tests were performed in a vacuum environment of the order of 10-4Pa at the bonding temperatures T=1053 to 1093K and at the bonding pressure P=3MPa. In the reaction diffusion acorss the interface full contacted by cold-pressure welding of Cu to Ag sheet, the width of the liquid layer is in proportion to the square root of the holding time. On the other hand, In the actual diffusion bonding, it is shown that there exists an apparent incubation period for the liquid-layer growth at the early stage of bonding. The liquid-spreading behaviour in the incubation period was examined. As a result, it is found that the liquid spreading process on the faying surface is achieved by three mechanisms, i.e., (1) the break-up of oxide film by the plastic flow and the reaction diffusion between insert and base metals, (2) the reaction diffusion across the exide film, and (3) the permeating operation between the faying surface and the liquid phase.
