(华中科技大学 材料成形与模具国家重点实验室，武汉 430074)
摘 要: 对压铸AlMgxSi2Mn(x=5.7~7.2)合金的微观组织进行分析，测试力学性能以及疲劳性能，研究镁含量对合金组织和力学性能的影响。结果表明：随着Mg含量的提高，合金屈服强度和布氏硬度分别提高了10.4%和9%，伸长率从8.3%降低至4.5%，抗拉强度则没有明显变化。疲劳寿命随着Mg含量的提高而提高，疲劳极限从57 MPa上升至75 MPa。合金的微观组织主要由α(Al)和Mg2Si相组成，Fe相则以颗粒状的Al3Fe和不规则形状的Al15(Fe,Mn)3Si2存在于晶界。Mn元素的加入也降低合金的粘模倾向。
关键字: 高压压铸；铝镁合金；疲劳性能；微观组织
（State Key Laboratory of Materials Processing and Die & Mould Technology,
Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:Microstructure observation, tensile test and fatigue tests were conducted to investigate the effect of magnesium content on microstructure and mechanical properties of die casting AlMgxSi2Mn (x=5.7-7.2) alloys. The results indicate that with magnesium content (mass fraction) increasing from 5.7% to 7.2%, the yield strength and brinell hardness increase by 10.4% and 9%, respectively. The elongation decreases from 8.3% to 4.5% and the ultimate tensile strength is stable. The fatigue life of alloys increases with enhanced magnesium contents and the fatigue limit increases from 57MPa to 75MPa. The microstructure of those alloys consists of α(Al) matrix and Mg2Si. Meanwhile, Al3Fe and Al15(Fe,Mn)3Si2 compounds distribute around grain boundaries. The addition of Mn reduces the die sticking tendency.
Key words: high pressures die casting; Al-Mg alloys; fatigue property; microstructure
