Thermal stability in nanostructured Al-5083/SiCp composites fabricated by cryomilling

Nanostructured Al-5083/SiCp composites, which consist of an ultrafine grained Al-5083 matrix reinforced with nanosized SiC particles, were fabricated via a cryomilling plus consolidation process. The thermal stability of these composites was studied by investigating the effects of annealing temperature on tensile properties and Vickers hardness of the composites and grain growth in the Al-5083 matrixes, with the annealing temperature ranging up to 873 K. The experimental results indicate that, after annealing at temperatures up to 773 K (0.90T(m), where T-m is 862 K, the melting onset temperature of the Al-5083 matrixes), the strength of the composites did not decrease significantly, while the grain size of the Al-5083 matrixes did not show a noticeable increase. The grains in some areas of the Al-5083 matrixes did not grow even after annealing at 873 K (1.01T(m)). The high thermal stability is attributed to the dispersion of native oxide particles observed at the lamellar interfaces created by cryomilling.