Abstract:The high-temperature air oxidation pretreatment process was applied to Al-12Si and Al-30Si alloy powders, and combined with hot-extrusion to fabricate SiO2 and Al2O3 dispersion strengthening composites. Optical microscopy and thermal physical testers analyzed the microstructure, density, hermeticity, coefficient of thermal expansion and thermal conductivity. The results show that: After powders oxidation, growth of Si grains in Al-30Si is more obvious than that of Al-12Si; the relative density of materials decreases with the increasing of oxidation time, but they are all higher than 97%. The hermeticity is about 1×10−9 Pa∙m3/s. Under the same process condition, the coefficient of thermal expansion of Al-30Si is much lower than that of Al-12Si, and the effect of oxidation time on coefficient of thermal expansion is not obvious. The thermal conductivity decreases with increase of Si content and increases with prolonging oxidation time, after oxidation 24 h, it exceeds 120 W/(m∙K).

Key words: high-silicon aluminum alloy; high-temperature air oxidation; coefficient of thermal expansion; thermal conductivity