Properties of dispersion hardened copper processed by internal oxidation in air
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The prealloyed copper powders containing different amount of aluminium (1, 2.5 and 3.5 mass.%) were milled for 5 h in a planetary ball mill to form alumina particles by internal oxidation in air. The powders were compacted by hot pressing in argon at 800 degrees C for 3 h. In the next step compacts were heat treated in argon at 800 degrees C for 5 h in order to determine their thermal stability via microhardness measurements. Compacts from as-received Cu-1, 2.5 and 3.5 mass.% A1 and non-alloyed electrolytic copper powders were also synthesized under the same condition. Compacts of milled powders before and after heat treatment exhibited considerably higher microhardness than compacts of non-alloyed electrolytic copper and as-received powders. The increase of microhardness and good thermal stability were ascribed to the small grain size and presence of fine and uniformly distributed alumina particles formed by internal oxidation during milling. The electrical conductivity of compacts wa...s above the minimum requirement limit for Cu-based alloys.