Precipitation strengthened high strength-conductivity copper alloys containing ZrC ceramics

Metal matrix composites (MMC) of copper and ZrC powders were prepared by the powder metallurgy route. Powders of both materials were introduced in stainless steel jag and mechanically mixed in a planetary mill under a protective atmosphere of argon during time ranging from 4 to 30 h. A characterization study of resulting powders indicated that a steady state particle distribution is developed after 12 h of milling. For this reason only these powders were consolidated by hot uniaxial pressing under 90 MPa at 923 K for 2 h. Residual porosity of these compacts was eliminated by rolling at 1073 K. Resulting materials present fine grained microstructure, tensile strength of 653 MPa and electrical conductivity up to 52% IACS. A detailed microstructural analysis by scanning and transmission electron microscopy showed not only ZrC particles but also the presence of very fine particles of carbides and oxides. WDX and EDX spectra of these particles revealed a high content of Fe and Cr for the carbides and Cu in the case of oxides.