Ag含量对Al-Mg-Si合金时效析出行为及性能的影响  

Effects of Ag Addition on the Precipitation Hardening Behaviour and Properties of Al-Mg-Si Alloys

作　　者：郑亚亚 罗兵辉[2] 汪力[1] 谢炜[3] ZHENG Yaya;LUO Binghui;WANG Li;XIE Wei(College of Energy and Electromechanical Engineering,Hunan University of Humanities,Science and Technology,Loudi 417000,Hunan,China;College of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]湖南人文科技学院能源与机电工程学院,湖南娄底417000 [2]中南大学材料科学与工程学院,长沙410083 [3]长沙理工大学工程车辆安全性设计与可靠性技术重点实验室,长沙410114

出　　处：《材料导报》2022年第13期153-157,共5页Materials Reports

摘　　要：采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、差热扫描热量法(DSC)和维氏硬度等手段研究了Ag含量对Al-Mg-Si合金组织、抗晶间腐蚀(IGC)性能、时效硬化和析出动力学过程的影响。结果表明:峰时效状态下,晶内主要强化相为β″相,晶界为β′相,同时晶界和晶内均存在少量的Al-Fe-Si(Mn)弥散相。随着Ag含量的增大,合金的峰值硬度提高,时效硬化速率增大。未添加Ag的合金晶界β′密度较大,腐蚀类型表现为晶间腐蚀和局部腐蚀;添加0.2%(质量分数,下同)Ag合金的晶界β′相连续程度较低,表现为轻微的IGC;过量Ag的添加导致晶界析出相连续程度提高,腐蚀敏感性增加。Ag的添加可降低MgSi原子团簇与Al基体界面的应变强度,促进团簇和β″的析出,降低了β″相的析出激活能,加快了Al-Mg-Si合金时效析出响应,提高了β″相的热力学稳定性。The effects of Ag content on microstructures,intergranular corrosion(IGC),age hardening and precipitation kinetics of Al-Mg-Si alloys were investigated by scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),differential scanning calorimetry(DSC)and Vickers hardness test.The results show that at the peak-ageing state,the main strengthening phase isβ″phase in the grain andβ′phase on the grain boundary,while there is a small amount of Al-Fe-Si-(Mn)dispersoid in both grain boundaries and grains.With the increase of Ag content,the peak hardness and age hardening rate increase.Without Ag addition,the density ofβ′phase on the grain boundary of the alloy is high,and the corrosion types of the alloy are IGC and local corrosion.The alloy with 0.2%(mass fraction,the same below)Ag has grain boundaryβ′phase of low continuity,and shows slight IGC.The addition of excessive Ag leads to the increase of continuity of grain boundary precipitates,and the increase of corrosion sensitivity.The addition of Ag can decrease the strain strength at the interface between MgSi clusters and Al matrix,promote the precipitation of clusters andβ″phase,decrease the precipitation activation energy ofβ″phase,significantly accelerate the aging precipitation response of the Al-Mg-Si alloy,and improve the thermodynamic stability ofβ″phase.

关 键 词：AL-MG-SI AG 晶间腐蚀 β″相 析出动力学 

分 类 号：TG146[一般工业技术—材料科学与工程]