NATURAL AGING BEHAVIOR OF CAST ALUMINA PARTICLE-REINFORCED 2618-ALUMINUM-ALLOY

The effect of the presence of 10 and 15 vol % alumina particles on the natural ageing behaviour of cast 2618 aluminium alloy was investigate d using microhardness measurements and differential scanning calorimet ry. It was found that the addition of the alumina particles does not a lter the ageing sequence of 2618 Al although certain aspects of the pr ecipitation reactions are changed. In particular, the relative quantit ies of the various phases were changed by reinforcement addition. Incr easing the alumina content decreased the volume fractions of the Guini er-Preston-Bagaryatskii (GPB) I phases. Also, the peak reaction temper ature, (T-p), for the GPBII and S' phases decreased with increasing vo lume fraction of alumina.