ABSTRACT The effect of mixed rare earth (La+ Yb) addition on the fluidity of A356.2 was investigated by fluidity tests, optical microscope (OM), environmental scanning electron microscope (ESEM) with energy diffraction spectrum (EDS) and X-ray diffraction (XRD). Varying amounts of (La+ Yb) addition were tested, 0%，0.3%，0.6%, and 0.9% (wt.%). The fluidity of A356.2 was improved with the addition of mixed rare earth (La+ Yb). The fluidity length of the A356.2 + 0.6% (La+ Yb) alloy (670mm) was increased by 19% compared to that of A356.2 (565mm). The fluidity of the alloy was related to the morphology of α-Al and Al8Si6Mg3Fe（Fe phase）in the alloy. A refined microstructure of the alloy corresponded with better fluidity. A higher pouring temperature also improved fluidity. However, this trend declined when the pouring temperature increased above 730°C.

中文翻译：

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(La+Yb)添加对A356.2铝合金流动性的影响

摘要 通过流动性测试、光学显微镜 (OM)、环境扫描电子显微镜 (ESEM) 的能量衍射谱 (EDS) 和 X 射线衍射研究了混合稀土 (La+ Yb) 添加对 A356.2 流动性的影响。 (XRD)。测试了不同量的 (La+ Yb) 添加量，0%、0.3%、0.6% 和 0.9% (wt.%)。A356.2的流动性通过添加混合稀土（La+Yb）得到改善。A356.2+0.6%（La+Yb）合金（670mm）的流动长度比A356.2（565mm）增加了19%。合金的流动性与合金中α-Al和Al8Si6Mg3Fe（Fe相）的形貌有关。合金的精细微观结构对应于更好的流动性。较高的浇注温度也改善了流动性。然而，当浇注温度升高到 730°C 以上时，这种趋势会下降。