时效路径对Al-0.7Mg-0.5Si-0.2Cu-0.5Zn合金沉淀析出行为的影响  

Effect of Ageing Routes on Precipitation Behaviors of Al-0.7Mg-0.5Si-0.2Cu-0.5Zn Alloy

作　　者：朱亮 郭明星[1,2] 袁波[1] 庄林忠[1,2] 张济山[1,2] ZHU Liang;GUO Mingxing;YUAN Bo;ZHUANG Linzhong;ZHANG Jishan(State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China;Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]北京科技大学现代交通金属材料与加工技术北京实验室,北京100083

出　　处：《金属学报》2020年第7期997-1006,共10页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2016YFB0300801;国家自然科学基金项目Nos.51871029;51571023和51301016;政府引导类计划-政府间双边创新合作项目No.BZ2019019。

摘　　要：利用DSC、TEM、拉伸实验以及硬度测试等方法系统研究了时效路径对高Mg/Si比Al-Mg-Si-Cu-Zn合金沉淀析出行为的影响。结果表明,固溶淬火态和预时效态合金在非等温时效过程中β″相的析出激活能分别为80.1和64.5 kJ/mol;在等温时效过程中表现出不同的时效硬化和组织演化行为,其中固溶淬火态合金时效硬化速率较快,但最终2种路径处理的合金峰值硬度和强度基本相同;但经预时效处理的合金,峰时效态延伸率和应变硬化速率以及过时效阶段硬度降低速率均较高。与此同时,预时效态合金还可析出大量复合溶质原子团簇,虽然在高温等温时效时会进一步长大,但使得欠时效、峰时效和过时效态合金的沉淀相尺寸呈多尺度特征,而固溶淬火后直接等温时效的不同状态合金却无此特征。时效路径并未改变合金沉淀析出序列,但对沉淀相形核、长大速率影响显著,据此提出了时效路径对沉淀相形核和长大过程影响的模型示意图。In order to reduce the weight of car body,Al-Mg-Si-Cu alloys have been widely studied and used to produce outer body panels of automobiles due to their favorable high-strength-to-weight ratio,recyclability and good formability.Moreover,the strength of Al-Mg-Si-Cu series alloys can be enhanced by bake hardening treatment.However,their formability and final strengths still need to be further improved compared to steels,which are the major obstacles to wide-scale application of Al alloys in the automotive fields.In this work,the effect of ageing routes on the precipitation behavior of Al-Mg-Si-Cu-Zn alloy with high Mg/Si ratio was systematically studied by DSC,TEM,tensile and hardness tests.The results show that the precipitation activation energies of theβ″phase formed in the non-isothermal ageing processes of the as-quenched and pre-aged alloys are 80.1 kJ/mol and 64.5 kJ/mol,respectively;both the different age hardening rates and microstructure evolution behaviors can be also observed during their isothermal ageing processes,such as,the age hardening rate of as-quenched alloy is much higher,but the peak hardness and strength values of the alloy treated by the two routes were basically the same.However,the elongation and strain hardening rate of the pre-aged alloy in the peak ageing state,and the hardness reduction rate in the over-ageing state are all much higher.In addition,a large number of complex solute clusters can be formed during pre-ageing,which will further grow in high temperature isothermal ageing process,but the sizes of precipitates formed in the under-ageing,peak-ageing and over-ageing states all show a multi-scale characteristics;in comparison,this feature cannot be found in the precipitates formed in the as-quenched alloy aged in the different conditions.The ageing routes cannot change the precipitation sequence of the alloy,but give a significant influence on the nucleation and growth rates of precipitates.As a consequence,a schematic diagram of nucleation and growth process of precipitates in

关 键 词：Al-Mg-Si-Cu-Zn合金 时效路径 预时效 非等温时效 等温时效 

分 类 号：TG146.21[一般工业技术—材料科学与工程]