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研究了半连续铸造AZ40镁合金铸态显微组织和均匀化热处理工艺。结果发现,心部的树枝状α-Mg和第二相化合物尺寸均大于边部;枝晶边缘的Al含量达到2.62%,形成具有一定宽度的Al富集区,而其心部的Al含量仅为0.59%,还有一部分Al以Mg17Al12和Al-Mn相形式存在;Zn和Mn在α-Mg内部均匀分布,Mn形成Al4Mn颗粒,Zn在Mg17Al12颗粒处富集。经410℃×4h均匀化处理后,Mg17Al12已基本回溶,而Al富集区尚未有效回溶。经410℃×24h均匀化处理后,Al富集区几乎完全回溶,基体中Al含量接近4.02%。
The as-cast microstructure and homogenization heat treatment process of semi-continuous casting AZ40 magnesium alloy were studied. The results show that the size of dendritic α-Mg and second-phase compounds in the heart is larger than that of the edge. The Al content in the edge of the dendrite reaches 2.62%, forming an Al-rich region with a certain width, while the Al content in the heart is only 0.59%, and a part of Al exists in the form of Mg17Al12 and Al-Mn phases; Zn and Mn are uniformly distributed in α-Mg, Mn forms Al4Mn particles, and Zn is enriched in Mg17Al12 particles. After 410 ℃ × 4h homogenization treatment, Mg17Al12 has been basically back-dissolved, while the Al-rich area has not yet effectively back-dissolved. After homogenization at 410 ℃ for 24h, the Al-rich region is almost completely dissolved, and the Al content in the matrix is close to 4.02%.