Effect of Multiple Shot Peening on Residual Stress and Microstructure of CNT/Al−Mg−Si Alloy Composite

In this study, multiple shot peening was performed on a carbon nanotubes−reinforced aluminum matrix composite, of which residual stress fields and tissue structure evolution were investigated. It is shown that the multiple shot peening could significantly increase the magnitude of compressive residual stress field, modify surface morphology of the specimens, and further refine the grain sizes of the near surface layer. Dislocation density in the near−surface layers were also elevated by multiple shot peening. Moreover, enhanced microhardness with more even distribution were obtained in the modified peened layers ascribed to the raised compressive residual stress field and microstructure which could give rise to the strain−hardening effects

Reinforcement with graphene nanosheets in aluminum matrix composites

Graphene has a high fracture strength of 125 GPa, making it an ideal reinforcement for composite materials. Aluminum composites reinforced with graphene nanosheets (GNSs) were fabricated for the first time through a feasible methodology based on flake powder metallurgy. The tensile strength of 249 MPa was achieved in the Al composite reinforced with only 0.3 wt.% GNSs, which is 62% enhancement over the unreinforced Al matrix. The relevant strengthening mechanisms involved in the GNS/Al composites were discussed along with experimental procedure

Effect of Multiple Shot Peening on Residual Stress and Microstructure of CNT/Al−Mg−Si Alloy Composite

In this study, multiple shot peening was performed on a carbon nanotubes−reinforced aluminum matrix composite, of which residual stress fields and tissue structure evolution were investigated. It is shown that the multiple shot peening could significantly increase the magnitude of compressive residual stress field, modify surface morphology of the specimens, and further refine the grain sizes of the near surface layer. Dislocation density in the near−surface layers were also elevated by multiple shot peening. Moreover, enhanced microhardness with more even distribution were obtained in the modified peened layers ascribed to the raised compressive residual stress field and microstructure which could give rise to the strain−hardening effects

Computational structural modeling and mechanical behavior of carbon nanotube reinforced aluminum matrix composites

International audienceDue to their remarkable mechanical properties, carbon nanotube (CNT) reinforced aluminum (Al) matrix composites have attracted a wide range of research interests. This work attempts to experimentally and numerically investigate the relationship between the micro-structures and mechanical behavior of CNT/Al composites. Three-dimensional (3D) computational structural modeling of CNT/Al composites is performed, in which the size, morphology, orientation, location and volume fraction of CNTs are reproduced to be similar to those of the actual micro-structures of CNT/Al composites. The strengthening of the mechanical properties of the constituent materials of CNT/Al composites and reasonable load and boundary conditions are studied based on the models of CNT/Al composites developed. The tensile mechanical behavior of CNT/Al composites is numerically evaluated and experimentally verified. Results show that the enhanced mechanical properties of CNT/Al composites can be attributed to three factors: CNT reinforcements, matrix grain refinement and layered architectures. Through the microscopic structural modeling methods presented herein, the effects of model size, interfacial behavior, volume fraction of CNTs and layered structures on the mechanical behaviors of CNT/Al composites can be reproduced to understand the strengthening and deformation mechanisms of CNT/Al composites

Thermal conductivity and interface characterization of diamond/aluminum composites fabricated by vacuum hot pressing

International audienc

Smart Mechanical Powder Processing for Producing Carbon Nanotube Reinforced Aluminum Matrix Composites

The central concern in the fabrication of carbon nanotube (CNT) reinforced metal composites is the well balance between uniform dispersion and structural integrity of CNTs. Rapid and uniform self-assembly of CNTs and spherical Aluminum (Al) particles into a core-shell structure is realized by a smart mechanical powder processing. The factors influencing the dispersion uniformity and structural integrity of CNTs during the processing are studied, including the size of Al particles, mixing speed and mixing time. It is revealed that a size of 35 μm is preferred for the Al particles to tear apart the CNT clusters and obtain a uniform dispersion of CNTs on Al surface. Different composite states, CNTs are singly dispersed, thickly wrapped, or embedded in the Al particles, can be obtained by changing the mixing speed. Well coordination between the CNT dispersion homogeneity and structural integrity could be achieved under suitable processing condition. Therefore, it can be adopted as an efficient and intelligent technology to achieve the desired performance in CNT/Al composites

Effect of interface evolution on thermal conductivity of vacuum hot pressed SiC/Al composites

International audienc

Diamond/aluminum composites processed by vacuum hot pressing: Microstructure characteristics and thermal properties

International audienc