采用半连续铸造制备了成分为Al-6Mg-0.4Mn-0.4(Sc-Zr),规格为300 mm×1000 mm的铝镁钪合金扁锭,研究了均匀化处理对铸态合金硬度、电导率和显微组织的影响.结果表明,铸态合金在均匀化处理过程中,350℃以下均匀化,合金硬度随退火温度升高而升高;350℃以上均匀化,合金硬度和硬度峰值随退火温度上升而降低,电导率则随退火温度的升高和保温时间的延长而单调上升.铸态合金均匀化处理过程中有类似于传统铝合金固溶时效过程中的析出特性,析出相主要为Al3(Sc,Zr),还有少量Al6Mn相粒子.硬度变化是半连续铸锭过程形成的含钪锆过饱和固溶体发生分解析出Al3(Sc,Zr)粒子所致.同时,含钪锆过饱和固溶体的分解析出导致基体固溶度的贫化,降低了合金的电子散射能力,合金的电导率升高.研究合金铸锭均匀化处理过程中Al3(Sc,Zr)粒子的最佳析出工艺为:300～350℃,6～8 h.
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