Numerical study of internal load transfer in metal/ceramic composites based on freeze-cast ceramic preforms and experimental validation
Numerical study of internal load transfer in metal/ceramic composites based on freeze-cast ceramic preforms and experimental validation
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DOI：
10.1016/j.msea.2013.07.022
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发表时间：
2013-11
期刊：
影响因子：
6.4
通讯作者：
Y. Sinchuk;Siddhartha Roy;J. Gibmeier;R. Piat;A. Wanner
中科院分区：
文献类型：
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作者：
Y. Sinchuk;Siddhartha Roy;J. Gibmeier;R. Piat;A. Wanner
本文对金属/陶瓷复合材料的弹塑性变形和内部载荷传递进行了数值和实验研究。该复合材料是在氧化铝悬浮液冷冻浇注干燥后制成的多孔开孔预制体中挤压浇注AlSi12熔体制备的。这种复合材料表现出由层状微区组成的复杂的微观结构。从散装材料中提取单域样品。在垂直于冷冻铸造方向的平面内，平行于金属合金和陶瓷片交替的方向进行了单轴压缩试验。选择该加载模式是因为当沿陶瓷片层加载时发生最高的加载转移。数值模拟采用基于金相二维截面的准三维显微组织有限元方法和改进的Voigt均匀化技术，该方法假定了金属合金的塑性行为、没有任何损伤和相间的理想界面。预测了不同陶瓷体积分数复合材料的内部载荷传递机理。结果表明，在任何外加应力下，随着陶瓷含量的增加，氧化铝中沿加载方向的相应力不断减小。通过原位压缩实验和能量色散同步辐射X射线衍射仪对数值结果进行了实验验证，样品的体积分数为41%。结果表明，两种数值方法得到的结果基本一致，与实验测量结果吻合较好。氧化铝中相应力与外加应力的比值在2~2.5之间达到最大值，直至300 Mpa左右的压应力。在较高的外加应力下，Al_2O_3中实验确定的晶格微应变和沿加载方向的相应力都会因为可能的损伤而减小。研究表明，实用、经济、灵活的均化技术是这种复合材料结构建模的一种可行工具。
The elastic–plastic deformation and internal load transfer in metal/ceramic composites are studied in this work both numerically and experimentally. The composite was fabricated by squeeze-casting AlSi12 melt in an open porous preform made by freeze-casting and drying of alumina suspension. Such composites exhibit a complex microstructure composed of lamellar domains. Single-domain samples were extracted from bulk material. Uniaxial compression tests were carried out parallel to the direction of the alternating metallic alloy and ceramic lamellae in the plane normal to the direction of freeze-casting. This loading mode is selected as highest load transfer occurs when loaded along the ceramic lamellae. Numerical modeling was done using the finite element method using quasi-3D microstructure based on metallographic 2D section and a modified Voigt homogenization technique assuming plastic behavior of the metallic alloy, absence of any damage and ideal interface between the phases. Internal load transfer mechanism was predicted for composites with different ceramic volume fractions. Results show that at any applied stress, as the ceramic content increases, the phase stress in alumina along the loading direction continuously decreases. Experimental validation of the numerical results is carried out by in-situ compression test along with energy dispersive synchrotron X-ray diffraction in one sample with 41 vol% ceramic. Results show that both the numerical techniques yield similar results, which match well with the experimental measurements. The ratio of the phase stress to the applied stress in alumina reaches a highest value between 2 and 2.5 up to a compressive stress of about 300 MPa. At higher applied stresses both the experimentally determined lattice microstrain and the phase stress along the loading direction in alumina decrease due to the initiation of possible damage. This study shows that the applied economic and more flexible homogenization technique is a viable tool for modeling of this composite structure.