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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 40 5nm)相似的Al3Er稀土化合物 ,起到非均质形核核心的作用
The microstructure of as-cast and homogenized annealed alloys after addition of 0 3% Er in LF3 aluminum alloy was investigated by means of metallographic microscope, scanning electron microscopy and X-ray diffraction. The results show that the addition of trace erbium can remarkably refine the as-cast microstructure of LF3 aluminum alloy, the dendritic cell size is obviously reduced, and the eutectic compound in network cell is also thinner. At the same time, the second phase compound is finer, The distribution is more uniform; addition of trace erbium can form Al3Er rare earth compounds, and no coarse massive compounds are found. The mechanism is due to the formation of LI2-type Al3Er rare earth compounds that are similar to Al matrix (face centered cubic, a = 0 40 5nm) both in crystal structure and in lattice constant, which act as a heterogeneous nucleation center