Abstract
Nanocrystalline (nc) Cu materials with Al₂O₃ dispersoid (1 and 5 vol.% Al₂O₃) were produced using the powder metallurgy (PM) techniques. The effect of reinforcement weight fraction, deformation temperature and annealing temperature (up to 800 °C) on the strength properties and the microstructure was studied. Two strengthening mechanisms were considered at room temperature, strengthening by grain refinements and dispersion strengthening (DS). The strength properties of both nc Cu composites were strongly dependent on deformation temperature and material composition. The main contribution of nanometric Al₂O₃ particles to the strength of composites at elevated temperatures is probably the strong pinning effect on the grain/crystallite boundaries and preventing of recrystallization process. After annealing at 0.74T_m both composites were characterized by an excellent stability of strength characteristics.

Key words
dispersion strengthened nanocrystalline copper, strengthening mechanisms, strength properties, microstructure

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