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.

Studies on the development of copper matrix composites with nanodiamond reinforcements have been carried out. The following process scheme was used: mechanical alloying of the initial components in planetary mills to produce granules of composite materials followed by compaction of the granules into bulk material. The studies have shown an increased oxidation of composite during its contact with air at a high content of nanodiamond reinforcing particles and small treatment time. Herewith, copper(I) oxide is mainly formed. As copper(I) oxide is toxic for marine organisms, it is suggested to use the obtained material for protection of marine facilities from biofouling. An increased treatment time leads to a uniform distribution of reinforcing particles in the matrix; no increased oxidation is observed. This material can be used for electronic packaging and to increase the wear resistance of articles.