Balanced Fracturing and Cold-welding of Magnesium during Ball Milling Assisted by Carbon Coating: Experimental and Molecular Dynamic Simulation

The lignite-derived carbon from self-protection pyrolysis was employed to balance the fracturing and cold-welding of magnesium during ball milling. Particle size analysis indicates that the introduction of lignite-derived carbon can effectively reduce the particle size of Mg while the introduction of graphite does no help. Besides, the effect of lignite-derived carbon on crystallite size reduction of Mg is also better than graphite. A moderate cold-welding phenomenon was observed after ball-milling Mg with the lignite-derived carbon, suggesting less Mg is wasted on the milling vials and balls. Molecular dynamic simulations reveal that the balanced fracturing and cold-welding of magnesium during ball milling is mainly attributed to the special structure of the lignite-derived carbon: graphitized short-range ordered stacking function as dry lubricant and irregular shape/sharp edge function as milling aid. The preliminary findings in current study are expected to offer implications for designing efficient Mg-based hydrogen storage materials.