Influence of fibre reinforcement on the aging behaviour of an AlSi12CuMgNi alloy

The aging behaviour of an AlSi12CuMgNi alloy reinforced with 20 vol.% Saffil and Fiberfrax, respectively, has been investigated by hardness measurements and differential scanning calorimetry. Taking the amount of fibres into account, the Saffil-reinforced alloy shows the same heat effect and hardness increase as the unreinforced alloy. In this composite the aging is accelerated, i.e. the maximum hardness is reached in about half the time of the unreinforced alloy. The Fiberfrax-reinforced alloy shows no aging effects at all. This is caused by the formation of an interface layer around the fibres in which Mg is enriched and therefore the formation of Mg2Si precipitates in the matrix is suppressed.