Quaternary and ternary interdiffusion experiments were performed on 7000-series alloys at 725 and 755K. The concentration profiles indicated that the diffusion distance of Cu was shorter than that of Zn or Mg in the solid solutions. The direct interdiffusion coefficients were positive, while the indirect coefficients were negative in ternary Al-Zn-Mg alloys. The effective interdiffusion coefficients in the 7000-series alloys were in the order: Zn > Mg > Cu. The ratios of the indirect to direct diffusion coefficients suggested that attractive interactions between Zn and Mg and between Cu and Mg occurred in the Al-Zn-Cu alloys.

Quaternary Diffusion in 7000 Aluminium Alloys. T.Takahashi, K.Hirayama, Y.Minamino, T.Yamane, Y.Koizumi: Journal of the Japan Institute of Light Metals, 2000, 50[10], 499-504