The effect of the connectivity of rigid phases on strength of Al-Si alloys

Abstract

The load carrying capacity of the eutectic Si in Al-Si alloys depends on its volume fraction, distribution, morphology and connectivity, namely its internal architecture. This can be modified by heat treatment at temperatures close to the eutectic point causing the spheroidisation and loss of connectivity of the eutectic Si. This decreases the load carrying capacity of the eutectic Si and, consequently, the room and high temperature strength of Al-Si alloys is reduced. The presence of other phases such as ceramic short fibres and aluminides in Al-Si alloys can result in the formation of hybrid three-dimensional structures that strongly delay and/or suppress the morphological changes and the loss of connectivity of the eutectic Si. As a result, the thermo-mechanical behaviour of these heterogeneous lightweight materials is improved and stable. These effects have been explored in the last years by the authors and the main results are compiled and presented in the present work with special emphasis in the relationship between the architecture and the strength of different Al-Si-based materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.