中文摘要：

采用光学显微镜（OM）、扫描电镜（SEM）和XRD物相定性分析研究了添加微量Sc和Er对Al-Cu-Mg系合金铸态组织的影响以及作用机制。结果表明：Er，Sc能不同程度细化合金铸态组织。合金中添加sc元素细化合金铸态组织的机制为凝固时形成的均匀分布的Al3（ScxZr1-x）质点成为αAl结晶时理想的异质核心，起到显著的晶粒细化作用。Er在合金中主要以Al8Cu4Er分布于晶界，并没有观察到Er和Zr元素的交互作用；凝固过程中，Er元素聚集在固液界面前沿，增大了凝固前沿的液相成分过冷度，抑制枝晶生长，从而细化晶粒。

英文摘要：

Three experimental Al-Cu-Mg-Zr alloys added with trace Sc and Er were prepared by ingot metallurgy （IM） method. The effect of additions with trace Sc and Er on the as-casting structure of the Al-Cu-Mg-Zr alloys was studied by using optical microscope, scanning electron microscope （SEM） and X-ray diffraction （ XRD）. The results show that the grain refinement of addition Sc to the alloy is attributed to the dispersive particle Al3 （ScxZr1-x） formed from the melt during the solidification proceeding. These particles refine as-casting grains remarkably and are the ideal nucleus of αAl growth. Er is assembled in the grain boundary in the form of A68Cu4Er. During solidification, Er is segregated at the front of liquid-solid phases interface and increases the composition undercooling of the alloys. It restrains the dendritic growth and refines the corresponding as-casting grain.