Hardened Aluminum with Oxide Particles

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 oC. 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

Hardened Aluminum with Discontinuous Copper Threads

The paper presents the influence of the quantity of discontinuous reinforced threads on the mechanical characteristics of some samples obtained through deformation from composite material with metallic matrix. As a raw material for obtaining the matrix it was used aluminum powder and as a reinforcing phase, short and long copper threads with different volumetric percentages. The products have been plastically deformed at a final diameter of 3 mm. The presence of the copper threads dispersed in the aluminum matrix in quantities of up to 16% copper (volumetric percentages), determines the hardening of the composite material. Above this limit the increase in the quantity of copper is no longer justified as it begins fragilizing the aluminum matrix