Interdiffusion in Solid Solution of the Al–Ag–Zn System at 832 K

Abstract

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.

Assessment of Atomic Mobilities in fcc Al-Ag-Zn Alloys

“…13 Comparison between the calculated and the experimentally measured interdiffusivities in fcc Al-Ag-Zn alloys [41,50] Fig. 11-14, respectively.…”

“…Figure 11 presents the calculated interdiffusivities in Al-rich Al-Ag alloys from 698 to 870 K compared with the corresponding experimental data from Neumann and Dittrich [40] and Minamino et al [37,41] Figure 12 is the model-predicted concentration dependence of interdiffusivites in fcc Ag-Zn alloys compared with the experimentally measured ones by Shimozaki et al, [47] Cheng et al [48] and Ugaste et al [49] It can be seen that the interdiffusivities in the fcc Al-Ag and Ag-Zn alloys can be predicted with the presently obtained atomic mobilities. Four sub-figures are constructed in order to give a concise comparison between the model-predicted and the experimentally measured isotherm ternary interdiffusivities by Minamino et al, [41,50] as are shown in Fig. 13.…”

“…Minamino et al [41,50] performed the measurement of the interdiffusivities in the Al-rich alpha solid solution of ternary Al-Ag-Zn system using the EPMA technique and the Matano method. Their early work focused on the isothermal diffusion at 832 K, while their later work emphasized the isothermal diffusion at 765, 785, 796, and 808 K. The measured major coefficients are positive, but the cross coefficients are negative.…”

Ternary Diffusion and Thermodynamic Interactions in α Cu–Ni–Sn Solid Solutions

“…The diffusion paths bend markedly and show Sshaped curves. The S-shaped diffusion paths have been observed in the Cu-Ni-Zn(16)(18), AlAg-Zn (19) and Cu-Mn-Zn(20) systems. The diffusion paths at the other temperatures are almost similar in shape to those in Fig.…”

Interdiffusion in α Solid Solutions of Cu–Al–Zn System

“…6(a) and (b), respectively. The temperature dependence of diffusion coefficients in ternary alloys have been investigated in the Fe-Ni-P system by Heyward and Goldstein (27), in the Ni-Co-Cr system by Leroy(28) and in the Cu-Ni-Zn and Al-Ag-Zn systems by the authors(6) (29). In Fe-Ni-P system, however, the temperature dependence of only the major coefficients have been studied.…”