Effects of the injection temperature of N-2 gas on pressureless infiltration for fabricating Al-Mg/Al2O3 composites

Abstract

Pressureless infiltration of molten Al-Mg alloys into particulate Al2O3 preforms has been known to occur only in a nitrogen atmosphere. In order to understand the pressureless infiltration mechanism of Al-Mg alloys into particulate Al2O3 preforms, nitrogen was injected at 25 degrees C, 300 degrees C, and 600 degrees C. The higher the injection temperature of the nitrogen gas was, the lower the infiltration temperature of the molten Al-Mg alloys into the particulate Al2O3 preform was. Pressureless infiltration of the Al-6Mg alloy occurred at 700 degrees C when the nitrogen gas was injected at 600 degrees C. The formation of an Mg-N compound (Mg3N2) on Al2O3 particles, which improves wettability by decreasing the interfacial energy between the Al-Mg alloys and the Al2O3 particles, enabled the formation of the Al-Mg alloy/Al2O3 composite via pressureless infiltration. Increasing the injection temperature close to the melting point of the Al-Mg alloys appeared to enhance the formation of Mg3N2 on the surface of the Al2O3 particles.