Small Additions Of Ag Research Articles

Small-angle neutron scattering from aged Al-Cu-Mg-Ag alloys

Small-angle neutron scattering has been used in a study of the precipitation mechanisms of an Al-5 wt.% Cu alloy doped with small additions of Ag and Mg. The experiments were carried out using the D11a instrument at ILL which was arranged to provide an observation range of 0.01<K<0.1 AA-1 with incident wavelengths between 8 and 12 AA. The high neutron flux available on this instrument permitted the collection of adequate statistics from each sample in a period of approximately 10 minutes. Three reaction temperatures of 120, 145 and 170 degrees C were selected for the experiment which was carried out in two parts: (i) with samples aged 'in situ' for periods of up to 19 hours; (ii) with samples pre-aged for greater periods up to completion of the reaction. The results indicated time- and temperature-dependent features which reflect detail concerning inter-zone/particle separations and particle size distributions throughout the reaction process. It is apparent from the scattering data that the mechanisms associated with GP zone formation in the doped alloy are markedly different from those operative in the classical binary Al-Cu system and the results were found to correlate well with other physical property measurements carried out on the system.