Hardened Aluminum with Oxide Particles

Abstract

The paper presents the effect of size and dispersion degree of the particles of aluminum oxide, on structure, mechanical characteristics and phenomena that take place when heating at different temperatures for recrystallization, for some samples obtained through deformation of superficially oxidized aluminum powder. The powder necessary for research had a grain size smaller than 40 μm and it was obtained in lab on a pulverization installation with air-jet. The fine film dispersion of oxide in the metallic matrix was obtained as an effect of extrusion with high degrees of the compressed products of superficially oxidized powder (from compressed with diameter of 20 mm to tests with diameter of 3 and respectively of 4 mm). For comparison reasons semi-products of cast aluminum were deformed under the same conditions. The maintaining temperatures of thermal treatment ranged from 350-550 C. At heating the oxide particles are stable and have a role of barrier against dislocations, therefore delay the interactions among dislocations and thus maintaining high mechanical resistances for the hardened aluminum matrix as compared to cast aluminum (without particles). The hardening effect through dispersion is as much higher as the deformation degree of tests from superficially oxidized powder increased, which determined o more pronounced finishing of the oxide particles and a greater dispersion of the fine oxide particles in aluminum matrix.