Infiltration of Al alloys into MgAl2O4 under different atmospheres

The reactions between spinel (MgAl2O4) and Al alloys of different compositions were investigated at temperatures of between 800-1250degreesC for different times under different atmospheres of air and nitrogen. Although Al metal did not infiltrate into the spinel in ambient atmosphere, oxide growth on the metal surface took place at temperatures of 1250degreesC depending on the alloy composition and firing time. Spontaneous infiltration of the Al metal into the spinel occured under nitrogen at 900degreesC. X-ray diffraction analysis revealed that the composite consisted of MgAl2O4, Al, MgO and Al2O3. The resultant microstructure was also investigated by scanning electron microscopy.