Microstructure and creep of Mo-ZrC in-situ composite

Microstructure and creep of arc-melted and annealed Mo-40 mol% ZrC in-situ composite were investigated in this study. Microstructure after annealing is found to consist of primary ZrC particles and fine Mo/ZrC eutectic structure, i.e. hyper-eutectic structure. Compressive creep tests in the temperature range from 1673 to 1873 K indicate that the stress exponent, n, is approximately 5 in the stress range from 100 to 500 MPa, and the apparent activation energy for the creep deformation is estimated to be about 500 kJ/mol at 200 MPa and 300 MPa. TEM observation for crept specimens shows that the creep deformation is accompanied with sub-boundary formation in Mo solid solution phase. It is suggested that the creep deformation of the composite in the temperature range examined is interpreted in terms of the dislocation creep of Mo solid solution phase controlled by the lattice diffusion of either Mo or Zr.