Grain Refinement Mechanism of MgAlON Composites Prepared by Spark Plasma Sintering

The paper developed a computing model to analyze the grain refinement mechanism of MgAlON composites sintered by spark plasma sintering (SPS). Using alumina, magnesia and aluminum as raw materials MgAlON composites were prepared by SPS. Based on the current assignment principle, the heating rate at different positions in Al grains was analyzed, and the particle radius during the sintering process could be calculated. The results suggested that necks could be formed between MgAlON particles with electric current heating rapidly to reduce particle radius, the shorter vertical distance from the interface was, the larger heating rate and growing rate of the neck had; the necks between particles be formed dynamically in the sintering process, so the big particle radius would be getting smaller and smaller continually so that we could get a large amount of micro particles distributed uniformly in the sintered MgAlON composites, and the resulted grain refinement was more obvious.