An X-ray small angle scattering investigation of an aged Al–20 wt.% Ag alloy

The changes observed in the scattering pattern during the initial stages of ageing an Al–20 wt.% Ag alloy at 220°C are reported. Patterns containing both the halo (resulting from G.P. zones) and streaks (resulting from platelets of Ag2Al) have been recorded. An analysis of these streaks shows that the platelets are no more than 9 A thick. This value is much smaller than that previously reported.