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对不同熔体冷却速度所制备稀土Y变质A356铝合金的显微组织及拉伸性能进行了研究。结果表明,随着熔体冷却速度的降低,初晶α-Al晶粒变得粗大且分布凌乱,其二次枝晶间距增大;共晶硅由颗粒状、纤维状转变为片状、针状;合金的拉伸性能显著下降,拉伸断口由韧性断裂向脆性断裂转变。稀土Y对熔体冷却速度较敏感,需在较大的熔体冷却速度下才能使共晶硅按变质形态生长。
The microstructure and tensile properties of Rare Earth Y modified A356 aluminum alloy prepared at different melt cooling rates were studied. The results show that as the melt cooling rate decreases, the primary α-Al grains become coarse and disordered, and the secondary dendrite spacing increases. The eutectic silicon changes from granular and fibrous to flaky and the needle Tensile properties of the alloy decreased significantly, tensile fracture transition from ductile fracture to brittle fracture. Rare earth Y on the melt cooling rate is more sensitive to the need for greater melt cooling rate in order to eutectic silicon by metamorphic growth.