Synthesis in a High-Energy Planetary Mill of Granules Based Onaluminum Alloy Containing Nanocrystalline Graphite

Resumo

Bulk nanocomposite granules based on AlMg2 alloy, containing nanocrystalline graphite, are prepared by mechanical synthesis using a high-energy ball mill. Structural and phase compositions are studied by optical metallography, computer-aided X-ray tomography, Raman spectroscopy and transmission electron spectroscopy methods. A model of the structural formation is proposed for the granules produced at rotation rates of 660 and 815 min–1. Granule structure consists of slightly-misorientated aluminum solid solution sub-grains with sizes from tens to hundreds nanometers. It is proposed that the initial micro- size graphite particles are subjected to mechanical splitting during mechanical milling. Nanocrystalline graphite particles are located between aluminum grains, as well as at several grain junctions. These nanocomposite granules have high micro-hardness. The granular aluminum-matrix nano-composites may find application during component manufacture by pressure forming and as the precursors for preparing composite alloys by liquid-phase methods.