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通过普通凝固方法,在铸锭冷却过程中进行水冷制备准晶强化Mg-Zn-Zr-Y镁合金,并研究不同Zn和Y含量(Y/Zn比相同)对通过这种制备方式获得的Mg-Zn-Zr-Y合金显微组织、显微硬度和热裂倾向的影响。结果表明:一定Y/Zn比的Mg-Zn-Zr-Y合金通过水冷冷却可获得更大的冷却速度,有利于获得更大体积分数的I-相(Mg3YZn6)。Y元素的添加使合金的成分过冷度增大,是铸态合金显微组织细化的主要原因。α-Mg基体中固溶的Zn含量是Mg-Zn-Zr-Y铸态合金基体硬度值的主要决定因素,I-相具有远高于α-Mg基体的硬度。Y元素引起合金液相线温度的大幅下降,固相线温度没有变化,从而减小了合金凝固区间,降低了铸锭的热裂倾向。
The quasicrystal Mg-Zn-Zr-Y magnesium alloy was prepared by ordinary solidification method during the cooling of the ingot. The effects of different Zn and Y contents (the same Y / Zn ratio) on the Mg -Zn-Zr-Y alloy microstructure, microhardness and hot cracking tendency. The results show that a larger cooling rate of Mg-Zn-Zr-Y alloy with a certain Y / Zn ratio can be obtained by cooling with water cooling, which is favorable for obtaining a larger volume fraction of I-phase (Mg3YZn6). The addition of Y element increases the undercooling of the alloy, which is the main reason for the microstructure refinement of the as-cast alloy. The content of Zn dissolved in the α-Mg matrix is the main determinant of the hardness of the as-cast Mg-Zn-Zr-Y alloy. The I-phase has much higher hardness than the α-Mg matrix. Y element causes the alloy liquidus temperature dropped significantly, the solidus temperature did not change, thereby reducing the alloy solidification interval, reducing the ingot hot cracking tendency.