中文摘要：

通过与计算相图数据库相耦合，建立了Al-Mg-Si三元合金体系中针棒状析出相时效析出动力学和时效强化模型，考虑了析出相形貌对形核、生长、粗化以及强化效果的影响．通过该模型可以获得不同时效工艺下析出相微观组织特征参数的变化及对应的屈服强度变化．利用该模型模拟了Al-Mg-Si合金在不同时效工艺条件下的时效析出过程和屈服强度变化，并与实验结果及Lifshitz—Slyozov．Wanger粗化模型计算结果进行了对比．基于模型研究并分析了析出相长径比、界面能、合金元素含量以及析出相成分对Al-Mg-Si合金时效析出动力学和强化效果的影响．结果表明：不同的界面能和长径比会影响形核密度和析出相尺寸，进而影响合金的屈服强度．增加基体中Mg含量可以促进时效析出，提高合金屈服强度，而基体中Si含量的增加对合金屈服强度并不产生明显影响．

英文摘要：

The aging hardening is the main strengthening mechanism of Al-Mg-Si alloys, and the hardening effect is determined by the microstructural features of precipitates including the morphology, composition, volume faction, nucleation density as well as the size distribution. In present work, an integrated mathematical model cou- pling with the CALPHAD sot~ware is developed to simulate the precipitation kinetics and strengthening effects of needle/rod-shaped precipitates in ternary Al-Mg-Si aluminum alloys. This model takes into account the effects of morphology on the nucleation, growth and coarsening of precipitates and on the strengthening effects. The yield strength model accounts for the whole precipitate size distribution, shape of precipitates and their specific spatial distribution based on the consideration of the competing shearing and bypassing strengthening mechanisms. Appli-cation of the model to various aging treatments of Al-Mg-Si alloys is conducted and the predictions both for micro- structural features and yield strength are validated with experimental results and the predictions by LSW model. Us- ing this model, the effects of aspect ratio, interracial energy, alloy composition and Mg/Si atom ratio in precipitates on precipitation kinetics and yield strength are investigated and analyzed. The results reveal that the different inter- facial energy and aspect ratio will affect the predicted density and size of precipitate, and further have an influence on the prediction precision of yield strength. An increase of Mg content in the matrix of Al-Mg-Si alloy will accel- erate the precipitation and improve the yield strength, while increasing the Si content in the matrix will produce lit- tle influence on the yield strength.