Al-20%Ag合金における復元

アルミニウム合金におけるG.P.ゾーンの成長と復元(第2報)

抄録

The mechanism of reversion in Al-20%Ag alloy aged at 70° or 130°C for different periods was investigated by measurements of electric resistivity and proof stress.
The resistivity of aged alloys was increased to the maximum, and then, decreased. While, the proof stress was only linearly decreased. The degree of reversion was satisfactorily explained in terms of the metastable miscibility gap given by Baur and Gerold.
The diffusion processes during the reversion was analyzed in reference to the metastable miscibility gap. It was shown that the reversion was due to the transition from η into ε zone, not due to the solution of G. P. zones. The activation energy of the diffusion of Ag during the reversion was determined to be 29.0kcal/mol by considering changes in the matrix concentration and the zone size depending upon the reversion temperature according to the metastable miscibility gap. The value was in remarkable agreement with the activation energy of diffusion of Ag in Al and Al-Ag alloy, or 29.0 and 28.9kcal/mol, respectively. Therefore, it was concluded that the rate controlling step in the reversion of Al-20%Ag alloy was the diffusion of Ag in Al-Ag solid solution.