(哈尔滨工业大学铸造教研室， 哈尔滨 150001)
摘 要: 研究了Al-Si-Mg系A357合金在不同时效状态下的显微组织、力学性能及形变特性。结果表明，时效条件不同，合金的强塑性配合不同，165℃短时时效，强塑性搭配较好；155 ℃，4 h预时效，再经175 ℃，12 h最终时效，进一步提高合金强度的同时,保证了塑性。不同温度下短时时效，析出物均为GP区，形变以位错切过的方式进行,长时时效，析出物均为β相，形变以位错绕过的方式进行。双级过时效处理，改善了 β相的析出形态，使得滑移位错均匀分布。
关键字: Al-Si-Mg合金 时效 显微组织 力学性能 位错
（School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001）
Abstract:The microstructure, mechanical properties and deformation characteristics have been studied for a cast Al-Si-Mg alloy A357 treated under different aging conditions. The results show that the mechanical properties vary with aging conditions. An optimum combination of strength and ductility was obtained by aging at 165 ℃ for a short time. Compared to this condition, pre-aging at 155 ℃ for 4 h and final aging at 175 ℃ for 12 h enhances strength properties without bringing about any loss in ductility. In the underaging condition which had GP zones, the deformation was carried out in the cut-off mode. In the overaging condition which had β precipitates, the dislocations were bowed out. In the step overaging condition in which the morphology of β phases becomes more mechanically ideal, the sliding dislocations are uniformly distributed in the deformation structure.
Key words: Al-Si-Mg alloy aging microstructure mechanical properties dislocation
