Abstract
Cu-15.6vol. % Ti(C, N) and Cu-3.1vol. % Ti(C, N) nanocrystalline powders were prepared by ball-milling Cu-l0at. % Ti and Cu-2at. % Ti powder mixtures containing small amounts of stearic acid in nitrogen gas for 200 h. During milling of the Cu-Ti powder mixtures, fcc-Cu phase was refined progressively to average grain sizes of about 20nm in diameter and formation of Ti(C, N) phase was detected by using X-ray diffraction, TEM and ESCA analysis. The milled powders were consolidated by using a HIP process under a pressure of 203 MPa at 1073 K for 2 h. By HIP-consolidating these MA powders, dence nanocrystalline materials of 98.1 and 98.3 % of theoretical bulk densities with average grain sizes of 55nm and 67nm were obtained for Cu-1 5.6vol. % Ti(C, N) and Cu-3.1 vol. % Ti(C, N) materials, respectively. After HIP-processing, the Cu-3. lvol. % Ti(C, N) materials were hot-rolled and subsequently annealed at several temperatures. The density of this material was increased to about 99.7 % by hot-rolling at 873 K, and the nanocrystalline structure having grain sizes between 50 and 100nm with the finely dispersed Ti(C, N). particals and some amounts of graphite particals was observed by HR-TEM. Such a nanocrystalline structure was stable up to the annealing temperature of 1273 K for 5 h.
