Modeling of precipitation hardening for the naturally aged Al-Mg-Si-Cu alloy AA6111

The effect of natural aging on the artificial aging behavior of the Al-Mg-Si-Cu alloy AA6111 is examined by isothermal calorimetry and the results are analyzed in a new kinetic model. The model describes the kinetics of concurrent precipitate formation and cluster dissolution during artificial aging of the alloy with variable levels of natural aging. The kinetic model is then combined with a recently developed yield strength model for AA6111 to predict the precipitation hardening behavior of the naturally aged alloy. The validity of both models is verified by agreement between the predictions of the models and independent experimental results. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.