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.