富铈混合稀土对Al-4.5Cu合金微观组织和力学性能的影响

Influence of Cerium-Rich Mischmetal on the Microstructure and Mechanical Properties of Al-4.5Cu Binary Alloys

在Al-4.5Cu铸造铝合金中添加微量的富铈混合稀土,用光学显微镜、扫描电镜以及能谱分析等手段研究稀土元素对合金组织、力学性能和断裂特性的影响。结果表明,稀土可以显著细化α-Al枝晶并减小二次枝晶间距;与此同时,枝晶间区域形成了骨骼状或块状稀土化合物相,Al2Cu和稀土化合物相相互交织在一起呈网状分布。添加富铈混合稀土后,合金的屈服强度略微降低,抗拉强度增加。添加富铈混合稀土改善了合金的塑性,合金延伸率增加至7.4%～8.84%,其断裂机制由脆性断裂转变为韧性断裂。

The influence of minor Ce-rich mischmetal on the microstructures, mechanical properties and fracture behavior were investigated by optical microscropy (OM), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Results reveal that the addition of Ce-rich mischmetal can refine the α-Al dendrites and reduce the secondary dendritic arm spacings. The RE-containing intermetallic compounds in the shape of blocky or skeleton are formed along the interdendritic regions. The Al 2 Cu phase and the RE-containing intermetallic compounds are joined together, showing network-like distribution. The Ce-rich mischmetal introduction reduces slightly the yield strength and improve the tensile strength. The elongation percentage of the alloys is improved remarkably, reaching 7.4%~8.84%, and the transition from brittle fracture to ducticle fracture occurrs.