Preparation and characterization of nanodiamond-reinforced 6061 aluminum matrix composites via a slurry process and high-energy ball milling

To solve the problems of easy agglomeration of nanodiamonds (NDs) and their poor adhesion to aluminum alloy matrices, a powder-metallurgical route based on a predispersion process using a slurry method combined with a short-term high-speed ball milling process was designed to fabricate ND-reinforced 6061 aluminum matrix (ND/ 6061Al) composites. In the slurry mixing process, oxidized ND was initially depolymerized and adsorbed on the surface of polyvinyl alcohol-modified 6061 aluminum powder through hydrogen bonding. It was demonstrated that for the predispersed powder, more rapid and homogeneous dispersion of ND was achieved in the subsequent high-energy ball milling process, which embedded ND into the aluminum powder to obtain better interface bonding and higher enhancement efficiency. The hardness and compressive strength of the extruded 1 wt% ND/ 6061Al composites were 111.3 % and 27.6 % higher than those of the 6061 aluminum matrix, respectively, and also outperformed the ND/6061Al composite directly fabricated by high-energy ball milling without predispersion.