Fabrication and properties of composite materials from the mixture of mechanically alloyed granules and copper powder

Abstract

Granules 45–315 μm in size are fabricated from powers of copper, its oxide, as well as aluminum and graphite by mechanical alloying in the attritor in air medium. Their structure represents a copper base with the grain size of 150–300 nm bordered by inclusions of the γ-Al2O3 phase 30–60 nm in size and small amounts of the Cu–Al2O3 phase and carbon are arranged. Microhardness of granules is in limits of 1500–2100 MPa. The samples of composite materials with the content of granules of 30, 50, and 70 wt.% are prepared by double compaction–sintering of a mixture of copper powder and mechanically alloyed granules. Their mechanical properties, electrical conductivity, and structure are investigated depending on the sintering temperature and amount of granules. Depending on the content of granules, properties of materials sintered at 900 °C, vary in the following limits: electrical conductivity is 55–70 % of electrical conductivity of copper of brand M1, hardness 60–93 HB, and tensile yield strength is 150–230 MPa. The strength and hardness increase with an increase in the weight fraction of granules, while electrical conductivity decreases. The structure of the material containing 30 % granules represents a copper matrix with granule-based inclusions, microhardness of which is 1150– 1700 MPa. A skeleton filled with a copper phase is formed in the samples containing 70 % granules. Hardness of the material with a weight fraction of granules of 50 % decreases less than by 15 % after annealing at 900 °C for 120 min.