中文摘要：

Al-7Si-Mg铸造铝合金的力学性能受凝固条件和热处理工艺参数的影响,如何建立各阶段工艺参数与微观组织、合金性能之间的定量化模型,对于优化工艺条件,提高合金性能具有重要的工程应用价值。建立了能够描述凝固、固溶处理和时效处理过程中微观组织演变的全过程、多尺度数值模型,并建立了相应强化模型,实现铸件最终屈服强度的预测。模拟了Al-7Si-Mg合金在各阶段的微观组织演变,并与实验结果进行了比较,分析了工艺参数对微观组织和合金屈服强度的影响规律。模拟和实验结果表明：二次枝晶臂间距随着冷却速率的增大而减小。Mg2Si颗粒的溶解和共晶Si的熔断在短时的固溶处理就可以完成。提高时效温度会促进时效析出,但会降低时效峰值强度,而增加Mg含量能够提高合金的屈服强度。最后分析了本模型存在的问题,指明该模型今后发展、充实与完善之处。

英文摘要：

The mechanical properties of Al-7Si-Mg cast aluminum alloys are controlled by solidification and heat treatment conditions,thus establishing quantitative models to correlate the processing parameters,microstructure and mechanical properties in each processing stage plays an important role in optimizing the processing parameters and thus improving the mechanical properties. The present paper presented a multi-scale numerical model involving the simulation of α-Al dendrite and（Al ＋ Si） eutectic growth by cellular automaton（CA） model during solidification,the prediction of dissolution of Mg2 Si phase and fragmentation and coarsening of eutectic silicon during solution treatment,the calculation of the precipitation kinetics during aging process as well as the final yield strength.Using this model,the microstructure evolution in each processing stage in Al-7Si-Mg alloys was firstly simulated,and the simulated results were compared with the experimental results. The influence of processing parameters on the microstructure evolution and yield strength was analyzed. The results revealed that the secondary dendrite arm spacing decreased with the increase of cooling rate. The dissolution of Mg2 Si phase and fragmentation of eutectic silicon were completed within a short time of solution treatment. Increasing the aging temperature dramatically accelerated the aging process,while the peak yield strength decreased. Increasing the Mg content could increase the yield strength. Finally,the problems and the further development of the model were pointed out.