Al-Zn-Mg-Cu-Zr-Sc合金铸态Al_3(Sc,Zr)相形貌的研究

Morphology of Primary Al_3(Sc,Zr) of As-Cast Al-Zn-Mg-Cu-Zr-Sc Alloys

采用金相显微镜、扫描电镜和能谱分析,研究Sc细化Al-Zn-Mg-Cu-Zr合金铸态组织的机制和一次Al3(Sc,Zr)粒子的形貌特征。结果表明:从熔体中析出的Al3(Sc,Zr)一次粒子是α(Al)固溶体的有效形核剂,该粒子以亚稳的L12型Al3Zr为核心,形成富钪与富锆Al3(Sc,Zr)层相间排列的多层复合结构。在Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr合金中添加0.20%～0.60%(质量分数)的钪,合金的铸态组织由粗大的树枝晶变为等轴晶,随着钪含量的增加,合金铸态组织得到进一步细化。

The morphology of primary Al3（Sc,Zr） particles in as-cast microstructure of Al-Zn-Mg-Cu-Zr-Sc alloys and the grain refinement mechanism of Sc on as-cast microstructure of Al-Zn-Mg-Cu-Zr alloys were investigated by optical microscope,scanning electron microscope（SEM） and energy spectrum analysis.Primary Al3（Sc,Zr） particles precipitated from the melt is an effective nucleating agent of α（Al） matrix with metastable Al3Zr（L12） as nucleation.The particle is of layered construction.Sc and Zr in primary Al3（Sc,Zr） particles distributed interleavingly with the Zr-rich core.Adding 0.20wt%-0.60wt% Sc to Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr alloys,coarse dendrite was changed into fine equiaxed grains.The higher content of Sc of alloys is,the finer as-cast grain is.