凝固速率跃迁对定向凝固Al-40%Cu过共晶合金初生Al2Cu相的影响
凝固速率跃迁对定向凝固Al-40%Cu过共晶合金初生Al2Cu相的影响
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DOI：
10.3724/sp.j.1037.2009.00706
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发表时间：
2010-04
期刊：
影响因子：
--
通讯作者：
QUAN Qiongrui,LI Shuangming,FU Hengzhi State Key L
中科院分区：
文献类型：
--
作者：
全琼蕊;李双明;傅恒志;QUAN Qiongrui,LI Shuangming,FU Hengzhi State Key L
金属间化合物结合了金属和陶瓷的特性，在凝固过程中表现出复杂的生长形态，与固相线相凝固不同，金属间化合物凝固过程中工艺参数与组织形态之间的关系还不清楚，本文考虑到金属间化合物Al_2Cu相具有众所周知的热物理性质，可用于理论和实验研究，对Al-Al_2Cu过共晶合金进行了定向凝固实验，实验中Al_2Cu相作为初生相凝固，初生Al_2Cu相的生长行为包括共晶与初生相之间的竞争生长，利用高梯度定向凝固装置，Al-40%Cu定向凝固组织当生长速率从10μm/s突变到2μm/s时，由于耦合共晶的界面生长温度超过了初生Al_2Cu枝晶的生长温度，合金组织发生了由初生Al_2Cu枝晶加枝晶间共晶向完全耦合共晶的转变。同时，在变生长速率实验中，初生Al_2Cu枝晶首先破碎成细小的枝晶，然后转变为共晶组织;它被解释为在固/液界面之前的液体溶质浓度的降低，而不是热的影响，此外，当生长速率从10μm/s突然降低到2μm/s时，观察到了初生Al 2Cu相由小面相向非小面相生长的形态变化，这可以用初生Al 2Cu相生长温度升高导致的杰克逊因子减小来解释。
Intermetallics combining metal and ceramic properties exhibit colorfully complicated growth morphologies in solidification.Different from the solidus phase solidification,intermetallic solidification remains less understanding of the correlation between processing parameters and microstructure morphologies.In this paper,considering that the intermetallic compound Al_2Cu phase has well-known thermophysical properties available for the theoretical and experimental research,we carried out the directional solidification experiments and focused on an Al-Al_2Cu hypereutectic alloy, where the Al_2Cu phase was solidified as a primary phase.The primary Al_2Cu phase growth behavior in the experiments included phase competition growth between coupled eutectic and primary phase, faceted phase transition and its change in growth morphology.By using a high thermal gradient directional solidification apparatus,the directionally solidified microstructures of Al-40%Cu(mass fraction) hypereutectic alloy were investigated and discussed based on the competition growth model.As the growth rate was changed abruptly from 10μm/s to 2μm/s,the microstructure transition from a primary Al_2Cu dendrite plus interdendritic eutectic to an entirely coupled eutectic occurred due to the interface growth temperature of the coupled eutectic exceeding that of the primary Al_2Cu dendrite. Also,the alloy liquid composition ahead of the solid/liquid interface approaching the eutectic point caused this microstructure transition.Simultaneously,in the changing-growth rate experiments,the primary Al_2Cu dendrites were firstly broken into small ones and then became the eutectic microstructure; it was interpreted rather by the decrease in liquid solute concentration ahead of the solid/liquid interface than by the effect of the thermal-solutal convection.Moreover,the morphology change in phase growth from faceted primary Al_2Cu phase to non-faceted phase was observed by reducing abruptly the growth rate from 10μm/s to 2μm/s,which can be explained by the Jackson factor decreasing with increasing the interface growth temperature of primary Al_2Cu phase.
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DOI：
10.1017/cbo9780511623165
发表时间：
1991-04
期刊：
--
影响因子：
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作者：
W. Tiller
通讯作者：
W. Tiller
DOI：
10.31399/asm.tb.pdub.t53420429
发表时间：
2004
期刊：
--
影响因子：
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作者：
D. Stefanescu
通讯作者：
D. Stefanescu
DOI：
10.31399/asm.hb.v09.a0003724
发表时间：
1990-06
期刊：
--
影响因子：
--
作者：
W. Kurz;D. Fisher
通讯作者：
W. Kurz;D. Fisher
DOI：
10.1007/978-3-319-15693-4
发表时间：
2002-06
期刊：
Science and Engineering of Casting Solidification
影响因子：
--
作者：
D. Stefanescu
通讯作者：
D. Stefanescu