High temperature creep behavior of in-situ TiB2 particulate reinforced copper-based composite

The tensile creep behavior of in-situ TiB₂ particulate reinforced copper-based (TiB₂/Cu) composite and unreinforced monolithic Cu fabricated by the powder metallurgy process was investigated at 773-873 K. The creep rate of monolithic Cu exhibited an exponential dependence on the applied stress, whereas the power-law relationship prevailed for the experimental data of the TiB₂/Cu composite. The composite exhibited a stress exponent of 25.5, 20.6 and 22.1 at 773, 823 and 873 K, respectively. Furthermore, the unreinforced Cu and in-situ TiB₂/Cu composite exhibited a creep activation energy of 187 and 444 kJ/mol, respectively. It is indicated, by incorporating a threshold stress into the analysis, that for the in-situ TiB₂/Cu composite, the true stress exponent was equal to 4.8 and the true activation energy was close to that for self-diffusion of copper, indicating that the creep of the composite is controlled by the lattice diffusion. (C) 2000 Elsevier Science S.A. All rights reserved.