Atomic composition/configuration dependent bulk moduli of Al–C composites
Atomic composition/configuration dependent bulk moduli of Al–C composites
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DOI：
10.1063/5.0117900
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发表时间：
2022-11
期刊：
影响因子：
1.6
通讯作者：
Hansika I. Sirikumara;W. Rativa-Parada;R. Karunanithy;P. Sivakumar;Sabrina Nilufar;T. Jayasekera
中科院分区：
文献类型：
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作者：
Hansika I. Sirikumara;W. Rativa-Parada;R. Karunanithy;P. Sivakumar;Sabrina Nilufar;T. Jayasekera
在金属中嵌入碳可以提高金属碳复合材料的机械性能。我们报道了通过热等静压方法生长Al-C复合材料的可能性，其中碳以石墨形式嵌入到Al晶格中而不形成Al 4C 3。拉曼光谱证实了铝晶格中sp2杂化碳簇的形成。测量样品的体积模量为60至100 GPa。从第一性原理密度泛函理论计算的结果来看，我们表明sp2杂化碳团簇的形成比铝中孤立的C散射体更稳定。我们的研究结果表明，扩展网络的C团簇表现出较高的体积模量，而孤立的散射中心会降低体积模量。我们用总电荷分布的分析解释了这种行为。电荷密度的局部化降低了材料响应外部应力的能力，从而显示出降低的体积模量。对于相同成分的Al-C复合材料，某些缺陷位形会降低基体位形的对称性，而另一些缺陷位形则保持基体位形的对称性。
Embedding carbon in metals has long been known to enhance the mechanical properties of metal carbon composites. We report the possibility of growing Al–C composites by the hot isostatic pressing method, with carbon embedded into an Al lattice in graphitic form without the formation of Al4C3. Raman spectroscopy confirms the formation of sp2-hybridized carbon clusters in the aluminum lattice. The bulk moduli of the samples were measured to be between 60 and 100 GPa. From the results of first principles density functional theory calculations, we show that the formation of sp2-hybridized carbon clusters is more stable than having isolated C scatterers in aluminum. Our results show that the extended network of C clusters shows a higher bulk modulus while isolated scattering centers could lower the bulk modulus. We explain this behavior with the analysis of total charge distribution. Localization of charge density decreases materials’ ability to respond to external stress, thus showing a reduced bulk modulus. Some defect configuration may reduce the symmetry while others keep the symmetry of the host configuration even for the same chemical composition of Al–C composites.