Microstructural evolution in semi-solid AA7034
Microstructural evolution in semi-solid AA7034
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DOI：
10.1007/s10853-007-2151-3
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发表时间：
2008-02
影响因子：
4.5
通讯作者：
Heesool Kim;I. Stone;B. Cantor
中科院分区：
文献类型：
--
作者：
Heesool Kim;I. Stone;B. Cantor
采用非原位粗化实验研究了喷射成形AA7034铝合金的半固态晶粒粗化动力学。当固相分数大于0.65时，合金的粗化速率常数随固相分数的增加而减小。当固相分数在0.6 ~ 0.65之间时，粗化速率常数随固相分数的增大而增大。当固相分数低于0.6时，随着固相分数的增加，粗化速率常数再次减小。建立了流动增强扩散模型来解释低固体分数下的晶粒粗化行为，其中粗化过程中不含半固体材料的宏观形状变化引起了流动。结合前人的液膜迁移模型和修正液膜迁移模型，流动增强扩散模型与已有的实验结果在定性上一致。
The kinetics of semi-solid grain coarsening in a spray-formed AA7034 aluminium alloy were determined by the use of ex situ coarsening experiments. The coarsening rate constant of the alloy decreases with increasing solid fraction for solid fractions greater than 0.65. For solid fractions between 0.6 and 0.65, the coarsening rate constant increases as the solid fraction increases. For solid fractions below 0.6, the coarsening rate constant decreases again with increasing solid fraction. A model of flow-enhanced diffusion was developed to explain the grain-coarsening behaviour at low solid fractions, with flow caused by the macroscopic shape change of the uncontained semi-solid material during coarsening. Together with previous liquid film and modified liquid film migration models, the flow-enhanced diffusion model shows qualitative agreement with available experimental results.