Correlation between resistivity increment and volume fraction of G.P. zones in an Al-3·2 wt % Zn-2·2 wt % Mg alloy

The correlation between resistivity increment caused by G.P. zones and their volume fraction has been investigated in an Al-3·2 wt % Zn-2·2 wt % Mg alloy. It is found that the resistivity increment is a linear function of the 2/3 power of the volume fraction. The results show that the resistivity increase is mainly determined by the total volume of zones and is not sensitive to their size distribution