Effects of the Injection Temperature of N_2 Gas on Pressureless Infiltration for Fabricating Al-Mg/Al_2O_3 Composites

摘要

Pressureless infiltration of molten Al-Mg alloys into particulate Al_2O_3 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 Al_2O_3 preforms, nitrogen was injected at 25 deg C, 300 deg C, and 600 deg 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 Al_2O_3 preform was. Pressureless infiltration of the Al-6Mg alloy occurred at 700 deg C when the nitrogen gas was injected at 600 deg C. The formation of an Mg-N compound (Mg_3N_2) on Al_2O_3 particles, which improves wettability by decreasing the interfacial energy between the Al-Mg alloys and the Al_2O_3 particles, enabled the formation of the Al-Mg alloy/Al_2O_3 composite via pressureless infiltration. Increasing the injection temperature close to the melting point of the Al-Mg alloys appeared to enhance the formation of Mg_3N_2 on the surface of the Al_2O_3 particles.