scholarly journals Several Aspects of Application of Nanodiamonds as Reinforcements for Metal Matrix Composites

2021 ◽  
Vol 11 (10) ◽  
pp. 4695
Author(s):  
Vladimir Popov

After detonation synthesis, primary nanodiamond particles are around 4–6 nm in size. However, they join into agglomerates with larger parameters and weak bonds between particles. The introduction of agglomerates into a metal matrix can lead to the weakness of composites. This paper demonstrates the possibility of obtaining a non-agglomerated distribution of nanodiamonds inside a metal matrix. The fabrication method was based on mechanical alloying to create additional stresses and deformations by phase transformations during treatment in a planetary mill. According to the findings, the starting temperature of the reaction between the non-agglomerated nanodiamonds and aluminium matrix reduces to 450 °C. Furthermore, the paper shows that existing methods (annealing for the transformation of a diamond structure into graphitic material and cleaning from this graphitic material) cannot reduce the sizes of nanodiamonds in the agglomerated state. Agglomerated nanodiamonds transform into carbon onions (graphitic material) during annealing in a vacuum in the following way: the nanodiamonds located in the surface layers of the agglomerate are the first to undergo the complete transformation followed by the transformation of nanoparticles in its deeper layers. In the intermediate state, the agglomerate has a graphitic surface layer and a core from nanodiamonds: cleaning from graphite cannot reduce nanodiamond particle size.

Author(s):  
A.S. Kalinichenko ◽  
V.Ya. Kezik ◽  
H.W. Bergmann ◽  
V.A. Kalinitchenko

Author(s):  
A. Lawley ◽  
M. R. Pinnel ◽  
A. Pattnaik

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.


Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
P. K. Liaw

Aluminum-based metal matrix composites offer unique combinations of high specific strength and high stiffness. The improvement in strength and stiffness is related to the particulate reinforcement and the particular matrix alloy chosen. In this way, the metal matrix composite can be tailored for specific materials applications. The microstructural characterization of metal matrix composites is thus important in the development of these materials. In this study, the structure of a p/m 2014-SiC particulate metal matrix composite has been examined after extrusion and tensile deformation.Thin-foil specimens of the 2014-20 vol.% SiCp metal matrix composite were prepared by dimpling to approximately 35 μm prior to ion-milling using a Gatan Dual Ion Mill equipped with a cold stage. These samples were then examined in a Philips 400T TEM/STEM operated at 120 kV. Two material conditions were evaluated: after extrusion (80:1); and after tensile deformation at 250°C.


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