In this study hot dip was executed on the surface of Al alloy with Zn-xAI alloy melt. The eutectic morphologies of Zn-xAl alloy ingots solidified in the crucible and Zn-xA1 coatings solidified on the aluminum surface were studied. The forming mechanism and influencing factors of eutectic structures with different cooling conditions were analyzed. The results show that the eutectic morphology of Zn-xAl alloy ingot was typical lamellar structure of nearly equilibrium solidification due to the lower cooling rate. The eutectic morphology of Zn-xAl alloy coating was anomalous due to rapid cooling rate; α Al-rich phases were spherical, spheroidicity or short rod-like structures. Thus the eutectic structure was determined by the cooling rate. Under different cooling conditions, leading phase of Zn-xAl that eutectic precipitates was Zn-rich β-phase.%在本研究中使用Zn-xAl合金液对铝合金表面进行热浸镀,重点研究不同Al含量的Zn-xAl合金液在坩埚中凝固的铸锭组织及在铝基体表面凝固的镀层组织中共晶形貌,分析了不同冷却条件下共晶组织的形成机理及影响因素.结果表明,Zn-xAl合金液铸锭由于冷速较低,属近平衡凝固,共晶组织为典型的片层结构；Zn-xAl合金液镀层的凝固由于冷速过快,冷却速度成为共晶结构的决定因素,共晶组织为非规则共晶形貌,α富Al相呈球形、椭球形或短棒状组织.试验中不同冷却条件下,Zn-xAl合金共晶析出时其领先相均为β富Zn相.
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