Evaluation of the creep properties of an Al-17Si-1Mg-0.7Cu alloy

The creep response of an Al-17%Si-1%Mg-0.7%Cu alloy was investigated in the temperature range between 280 and 380 degreesC. The creep curves exhibited a short primary region, followed by a minimum creep rate range and by a long tertiary stage. The minimum creep-rate dependence on applied stress was very similar to that observed in a composite with a 6061 (Al-1%mg-0.5%Cu) matrix and reinforced by 20% Al2O3 particles. On the basis of this evidence and of the distinctive structure of the alloy, the creep response of Al-17%Si-1%Mg-0.7%Cu was described following the approach generally used for aluminum-based metal-matrix composites. The threshold stress, which represents the strengthening,effect resulting from the interaction between dislocation and finely dispersed particles, was calculated at each temperature and compared with that calculated for the 6061 20Al(2)O(3) composite. The results of this comparison unambiguously demonstrate that the creep strength of the Al-17%Si-1%Mg-0.7%Cu is even higher than that of the composite. (C) 2002 Elsevier Science B.V. All rights reserved.