蛇形通道制备半固态A380铝合金浆料组织的演变  

Microstructure evolution of the A380 aluminum alloy semi-solid slurry prepared by serpentine channel

作　　者：刘志勇[1] 毛卫民[1] 王伟番 郑志凯[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《工程科学学报》2016年第2期263-269,共7页Chinese Journal of Engineering

基　　金：国家重点基础研究发展计划资助项目(2011CB606300);国家自然科学基金资助项目(50774007)

摘　　要：采用石墨质蛇形通道制备半固态A380铝合金浆料,并研究浆料制备过程中浆料组织的演变.结果显示,合金熔体在蛇形通道内发生一次凝固,在其通道内壁的激冷和异质形核作用下形成大量的初生自由晶,半固态浆料的剩余液相在收集坩埚内发生二次凝固形成二次非枝晶.初生晶粒的游离模型表明一部分初生自由晶直接生长为球晶,其他部分则成长为枝晶,枝晶在'自搅拌'的作用下发生缩颈和熔断,通过'自旋转'在蛇形通道内得到初步球化和熟化.二次凝固形成的二次非枝晶在收集坩埚内得到初步球化和熟化,同时初生晶粒在收集坩埚内得到进一步球化、熟化和均匀分布.The semi-solid slurry of A380 aluminum alloy was prepared by using a graphite serpentine channel and the microstruc- ture evolution during solidification was investigated. The result showed that, initial solidification occurred in the serpentine channel, and a large number of primary free grains generated in the alloy melt under the influence of chilling and heterogeneous nucleation caused by the serpentine channel inner wall. Secondary non-dendrites formed during secondary solidification which occurred in the remaining alloy melt of the semi-solid slurry in the collective crucible. The drifting model of primary grains displayed that a part of primary free grains directly grew to spherical grains, and others developed to dendrites. The ＂self-stirring＂ of the alloy melt made dendrites neck and fuse, and they got initial spheroidization and ripening through the ＂ self-rotating＂ in the serpentine channel. Secondary non-dendrites formed during secondary solidification got initial spheroidization and ripening in the collective crucible. Mean- while, the primary grains got further spheroidization, ripening and uniform distribution in the collective crucible.

关 键 词：铝合金 半固态浆料 蛇形通道 组织演变 游离 

分 类 号：TG249[金属学及工艺—铸造] TG146.21[一般工业技术—材料科学与工程]