(哈爾濱工業(yè)大學鑄造教研室， 哈爾濱 150001)
摘 要: 研究了Al-Si-Mg系A357合金在不同時效狀態(tài)下的顯微組織、力學性能及形變特性。結(jié)果表明，時效條件不同，合金的強塑性配合不同，165℃短時時效，強塑性搭配較好；155 ℃，4 h預時效，再經(jīng)175 ℃，12 h最終時效，進一步提高合金強度的同時,保證了塑性。不同溫度下短時時效，析出物均為GP區(qū)，形變以位錯切過的方式進行,長時時效，析出物均為β相，形變以位錯繞過的方式進行。雙級過時效處理，改善了 β相的析出形態(tài)，使得滑移位錯均勻分布。
關鍵字: Al-Si-Mg合金 時效 顯微組織 力學性能 位錯
（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
