Evolution of pore morphology and distribution during the homogenization of direct chill cast Al-Mg alloys
Evolution of pore morphology and distribution during the homogenization of direct chill cast Al-Mg alloys
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DOI：
10.1016/j.actamat.2006.08.023
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发表时间：
2007-01-01
期刊：
影响因子：
9.4
通讯作者：
Nagaumi, H.
中科院分区：
文献类型：
--
作者：
Chaijaruwanich, A.;Lee, P. D.;Nagaumi, H.
研究了直冷（DC）铸造铝镁合金均匀化热处理过程中孔隙率的演变。均质化热处理在 530 摄氏度下进行不同的保温时间（0、1、10 和 100 小时）。使用二维金相学和三维 X 射线显微断层扫描 (XMT) 技术对孔隙率的演变进行量化。金相数据表明，平均孔径、最大费雷特长度和孔隙率在均质化过程中均增加，这可能是通过经典的孔间奥斯特瓦尔德熟化来解释的。然而，孔数密度也增加了，当孔间粗化是控制机制时，这是预料不到的。进行 XMT 是为了阐明这一明显的矛盾。 XMT数据显示，直流铸造中形成的孔隙网络的曲折性非常复杂，并且在均质化过程中最大孔隙长度没有增加。相反，曲折孔隙网络的孔内奥斯特瓦尔德成熟是驱动孔隙形态演化的关键机制，粗糙体和互连结构的粗化是由其高局部曲率驱动的。开发了空位扩散的一维模拟并证实了这一结论。 (c) 2006 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
The evolution of porosity during homogenization heat treatment of direct chill (DC) cast Al-Mg alloys was studied. Homogenization heat treatment was performed at 530 degrees C for various holding times (0, 1, 10 and 100 h). The evolution of porosity was quantified using two-dimensional metallography and three-dimensional X-ray microtomography (XMT) techniques. The metallographic data suggested that the mean pore size, maximum Feret length and percentage porosity all increased during homogenization, which might be explained by classical inter-pore Ostwald ripening. However, the pore number density also increased, which is not expected when inter-pore coarsening is the controlling mechanism. XMT was performed to elucidate this apparent contradiction. XMT data revealed that the tortuousity of the pore networks formed in DC casting was very complex and that there was no increase in maximum pore length during homogenization. Instead, intra-pore Ostwald ripening of the tortuous pore networks was the key mechanism driving the evolution of pore morphology, with coarsening of both the asperities and interconnects being driven by their high local curvatures. A one-dimensional simulation of vacancy diffusion was developed and corroborated this conclusion. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.