[论文解读] Graphene platelets reinforced aluminum matrix composite with enhanced strength by hot accumulative roll bonding

Jitendar Kumar Tiwari, Ajay Mandal+3 more|arXiv (Cornell University)|Jun 30, 2018

Aluminum Alloys Composites Properties参考文献 24被引用 7

一句话总结

本研究通过热累积轧制堆焊（ARB）工艺制备了少层石墨烯片（GNPs）/铝基复合材料，通过界面混合有效防止了石墨烯团聚，使屈服强度提高73%，硬度提高27%，同时保持了良好的塑性。该工艺显著提升了GNP的分散性与界面结合力，实现了显著的强化效果并保留了塑性。

ABSTRACT

Accumulative Roll Bonding(ARB) process was used to develop few-layer graphene nano platelets reinforced aluminum matrix (GNPs/Al) composite in the form of sheets. Annealed Al sheets were ARB processed up to 6 pass along with coating of graphene between stacked sheets in first and second pass. Another set was prepared with same process parameter in the absence of graphene coating. Properties of these two set of samples were analyzed on the basis of film theory of ARB process which enables micro-level mixing of material on stacked layer interface. Hence the problem of graphene agglomeration was overcome through our process. The Raman spectra at the cross-section was taken which not only show the strong interaction of GNPs with Al matrix due to increased D and D' band but also the graphene quality enhancement on the basis of single symmetric 2D band. Samples were then subjected to universal testing machine (UTM) and Vickers microhardness tester. Results showed up to ~73% increment in yield strength and ~27% increment in hardness of GNPs/Al matrix composite. Fracture surface of tensile specimen was further examined under SEM to understand the fracture mechanics at higher passes, which elucidate elongation variation and delamination behavior of stacked sheets. Deep elongated dimples with the smoothed surface in GNPs/Al composite are the cause of reduced elongation. But the final composite was having improved strength with appreciable ductility. The improvement was further justified by increment in dislocations, calculated using Williamson-Hall plot on X-ray diffraction (XRD) data. All results signify the effectiveness of the proposed technique for the development of GNPs/Al composite.

研究动机与目标

• 开发一种可扩展的工艺，用于制备高强度少层石墨烯片（GNPs）增强的铝基复合材料。
• 克服金属基复合材料在加工过程中石墨烯团聚的挑战。
• 通过ARB的薄膜理论，增强铝基体中GNP的界面结合力与分散性。
• 评估所得GNPs/Al复合材料的力学性能，包括强度、硬度和塑性。
• 利用XRD、拉曼光谱和SEM分析，建立微观结构演化与力学性能之间的关联。

提出的方法

• 对退火铝板进行热累积轧制堆焊（ARB），最多进行6道次。
• 在第一道和第二道次过程中，将石墨烯片涂覆于铝板之间，以确保界面混合。
• 利用ARB的薄膜理论促进层间微尺度混合，减少GNP团聚。
• 采用Williamson-Hall图对X射线衍射（XRD）数据进行分析，以量化位错密度的增加。
• 对横截面进行拉曼光谱测试，以评估GNP的质量及其与铝基体的相互作用。
• 采用万能试验机（UTM）和维氏显微硬度计进行力学性能测试。

实验结果

研究问题

• RQ1 热AR B工艺能否在不发生团聚的情况下有效分散铝基体中的石墨烯片？
• RQ2 通过ARB薄膜理论实现的界面混合如何影响GNPs/Al复合材料的力学性能？
• RQ3 拉曼光谱的变化在多大程度上反映了GNP与铝基体之间的相互作用？
• RQ4 位错密度的增加与复合材料中观察到的强化效应之间存在何种关联？
• RQ5 经过多道次AR B处理后，GNPs/Al复合材料的断裂行为与塑性之间的权衡如何？

主要发现

• 经过6道次AR B处理后，GNPs/Al复合材料的屈服强度相比纯铝提高了73%。
• 由于GNP的有效分散和界面强化，复合材料的硬度提高了约27%。
• 拉曼光谱显示，2D带对称性增强，D带和D'带强度增加，表明GNP与铝基体之间存在强相互作用。
• 通过SEM对断口表面的分析显示，存在深而拉长的杯锥形凹坑，表面光滑，解释了尽管强度提高但延伸率降低的原因。
• Williamson-Hall图证实位错密度显著增加，直接贡献于观察到的强化效果。
• 复合材料保持了可接受的塑性，表明强度与成形性之间达到了良好的平衡。