diffusion profiles have been determined, and then the diffusion paths have been drawn in the ternary composition triangle. The interdiffusion coefficients and have been determined by Matano's method. The four coefficients have been found to be sensitive to the solute concentration. The diffusion profiles and paths have been also calculated by the solution of Fujita et al. and by the finite-difference method using the experimental values of the four interdiffusion coefficients. Good agreements have been found between the experimental and calculated both of them. (Received April 16, 1983) Keywords:interdiffusion, aluminum-silver-zinc alloy, diffusion couple, interaction parameter, finite-difference method Many investigations of diffusion have been performed on binary alloys. On the other hand, only about twelve studies on ternary diffusion have been reported in substitutional solid solution of Al-, Cu-and Fe-alloys(1)-(12), since interdiffusion in a binary alloy can be described by only one interdiffusion coefficient D and four interdiffusion coefficients are necessary to describe the interdiffusion in a ternary alloy.The purpose of this study is to investigate the solution of the Al-Ag-Zn ternary system at 832K.
Preparation of diffusion couplesEleven diffusion couples were prepared. Two of them were those for the binary diffusion. Chemical compositions of couples are listed in Table 1. The alloys were prepared from 99.996%Al, 99.9%Ag and 99.996%Zn, and then homogenized at 789K for 690ks. Some ing in sodium hydroxide and phosphoric acid solution, the rods were inserted into the holes of the blocks, in order to make the diffusion marker.The composite metals were heated at 783K for 600s, and then rolled into 7.6mm in thickness. The rolling is practical and also has the advantage that the oxide film at the interface between the alloys is broken up and distributed over a much larger area(13)• The rolled metals were cut into 5mm in width as the diffusion Table 1 Terminal compositions of the diffusion couples.