Microstructural evolution in MgOp/AlN composites

MgOp/AlN composite has been fabricated by directed melt nitridation of pure Al block covered with a powder mixture of 0.5–1 mm magnesia particles and 0.075–0.15 mm chemically pure magnesium powder in flowing N2 in the range of 900–1200 °C. The extent of Al nitridation and the depth of Al penetration into the MgO particles increases with temperature. The phase composition in the matrix from metal rich to ceramic rich can be adjusted by controlling processing temperature. A multilayer microstructure of MgO/MgAl2O4/AlN surrounds the MgO particles due to the interface reaction. The thickness of each layer in this structure varies with processing parameters such as the temperature and local Mg concentration, depending on the influence of these processing parameters on the interface reaction of MgAl2O4 formation and Al nitridation.