摘要
利用DSC、TEM、拉伸和硬度测量等方法系统研究了Al-0.8Mg-1.2Si-0.5Cu-0.3Mn-0.5Fe(-3.0Zn)(质量分数,%)合金非等温时效析出行为。结果表明,添加Zn可增加合金低温区和高温区溶质原子团簇析出和回溶量,并促进沉淀相析出,基于DSC分析计算的沉淀相析出激活能和其他材料参数,分别建立了可有效预测2种合金沉淀析出速率的动力学方程;同时,3.0%Zn的添加可有效促进合金非等温热处理时效过程中沉淀相的形核率,致使硬度较高,与不含Zn合金一样其硬度均随时效温度升高而升高,100℃附近升高缓慢,出现一硬度平台,250℃附近出现硬度峰值,随后降低;峰值状态的TEM组织表征显示,非等温热处理可使2种合金均析出大量多尺度β″沉淀相,但是含Zn合金沉淀相数量密度更高,且析出的β″相晶格参数发生显著变化;此外,基于组织和性能测量,建立了2种合金峰值状态沉淀相分布与显微硬度间的经验定量关系。
To reduce the weight of a car body,Al-Mg-Si-Cu alloys have been extensively studied for outer body panels of automobiles owing to their high strength-to-weight ratio,recyclability,and good formability.Moreover,the strength of Al-Mg-Si-Cu series alloys can be enhanced using the bake-hardening treatment.However,compared with steel,the formability and final strengths of the alloys need further improvement,which is a major challenge to the large-scale application of Al alloys in the automotive fields.In this study,the non-isothermal precipitation behavior of Al-0.8Mg-1.2Si-0.5Cu-0.3Mn-0.5Fe(-3.0Zn)(mass fraction,%)alloy was systematically investigated using DSC,TEM,tensile test,and hardness measurements.The results show that adding Zn can simultaneously increase the formation and redissolution of solute clusters in the alloys during low-and high-temperatures non-isothermal heat treatments and promote precipitation.The kinetic equations of precipitation in the two alloys were established based on the activation energy of precipitation obtained through DSC analyses and other material parameters,which can effectively predict the corresponding precipitation rates.Further,adding 3.0% Zn to the alloy can effectively increase the nucleation rate of the precipitates in the alloy during non-isothermal heat treatment,resulting in higher hardness.Additionally,with the increase of ageing temperature,the hardness increased gradually,but a hardness plateau appeared at approximately 100℃,and the peak hardness values appeared at approximately 250℃,followed by a decrease in hardness.TEM microstructural characterization showed that non-isothermal heat treatment could result in the formation of multiscale β''precipitates in the two alloys in the peak ageing state.In comparison,adding Zn to the alloy increased the number density of the precipitates and significantly changed the lattice parameters of β''phases formed in the peak aged alloy.Finally,based on the obtained microstructure and mechanical properties,the relationship between the precipitate distribution and microhardness of the two alloys was established.
作者
袁波
郭明星
韩少杰
张济山
庄林忠
YUAN Bo;GUO Mingxing;HAN Shaojie;ZHANG Jishan;ZHUANG Linzhong(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)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第3期345-354,共10页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.51871029,51571023和51301016
国家重点研发计划项目No.2016YFB0300801
政府引导类计划-政府间双边创新合作项目No.BZ2019019
新金属材料国家重点实验室开放课题项目No.2020-ZD02。
