Synthesis of nanodiamond reinforced silver matrix nanocomposites: microstructure and mechanical properties

Abstract: Nanodiamond reinforced silver matrix nanocomposites with different nanodiamond content are produced from pure silver and nanodiamond powders by a combination of two severe plastic deformation methods, ball-milling and high-pressure torsion (HPT). The ball milling parameters are varied to improve the distribution of the nanodiamonds in the powder blends. An optimized processing route combining both processes has been developed to achieve a homogenous dispersion of small nanodiamond particles in a nanocrystalline silver matrix. The microstructure of these nanocomposites was characterized by scanning and transmission electron microscopy. The mechanical properties were characterized by microhardness measurements and tensile tests. An increasing amount of nanodiamonds (up to 5 wt% and 15 vol%, respectively) can raise the microhardness by up to 70 % and the tensile strength by up to 60 % of the values achieved in HPT deformed pure silver. The microhardness and tensile strength is about 5 times higher than microcrystalline pure silver.