微量铒对LF3铝合金铸态组织的影响

采用金相显微镜，扫描电镜和X射线衍射仪等手段分析研究了LF3铝合金中添加0．3％Er后的合金铸态及均匀化退火态的组织。结果表明：微量铒的加入可显著细化LF3铝合金的铸态组织，使其枝晶网胞尺寸明显减小，网胞间共晶化合物也更稀薄；同时，使第二相化合物更细小，分布也更均匀；微量铒的加入可形成Al3Er稀土化合物，没有发现粗大的块状化合物。其机制是由于生成了LI2型结构的，在晶体结构和点阵常数上都与Al基体（面心立方，a=0.405nm)相似的Al3Er稀土化合物，起到非均质形核核心的作用。

Effects of Trace Erbium on Casting Microstructure of LF3 Al-Alloy

Microstructures of casting and annealing LF 3 aluminum alloy with 0 3% erbium were studied by means of Optical Microscope, Scan Electronic Microscope and X ray. The experiment results show that the addition of trace erbium will remarkably refine casting microstructure of LF 3 Al alloy, the grain refinement results in decreased branching of the dendrites and the eutectic compound, make the secondary phase more miner and the phase distribute dispersively, and it can produce a rare earth compound of Al 3Er. There is no coarse block compound in the LF 3 Al alloy addition trace erbium. The mechanism is the formation of Al 3Er compound with the similar crystal ( LI 2) and lattice to Al matrix (fcc, a =0 405 nm), as the heterogeneous solidification nuclei.