Fabrication of Al-3 Wt Pct Mg Matrix Composites Reinforced with Al2O3 and SiC Particulates by the Pressureless Infiltration Technique

摘要

In Al-3 wt pct Mg/ Al2O3p (or SiCp) compositesfabricated by the pressureless infiltration method, theinfiltration behavior of molten metal, the mechanical properties,and the interfacial reactions were investigated. Thespontaneous infiltration of the molten Al-3 wt pct Mg alloyinto the powder bed occurred at a relatively low temperature(700℃ for 1 hour under a nitrogen atmosphere).Spontaneous infiltration of the molten metal is related to theformation of Mg3N2 by the reaction of Mg and nitrogen. Thetensile strength and 0.2 pct to offset yield strength andelongation tend to decrease with increasing infiltrationtemperature and time, because of an increased interfacialreaction. In Al-3Mg/ Al2O3 composites, MgAl2O4 wasobserved at interfaces between Al2O3 and the matrix, as well asat oxide films of the Al powder surface. In addition, MgO wasobserved at interfaces between Al2O3 and the matrix. On theother hand, Al4O3 was formed at interfaces between SiC andthe matrix in Al-3Mg/SiC composites. In addition, Mg Al2O4was observed as a reaction product at the interfaces betweenoxide films of SiC and the matrix, as well as at oxide films ofthe Al powder surface. Since the Si released as a result of theinterfacial reaction is combined with Mg, age hardening canoccur by the precipitation of Mg2Si via T6 treatment.