Abstract
Tensile tests, creep tests and SEM observation of fractured surfaces are made to investigate deformation characteristics of sintered tungsten wires of 1.0 mm in diameter at intermediate temperatures. The failure occurs with no cup-and-cone fracture because of the chisel-edge type failure of individual fibers, giving several microcracks running along the separated fibers in the radial directions at the temperature range of 600 to 800 K. The number of microcracks decreases with increasing temperature and the double cupped fracture is observed at 1300 K. Typical curves are obtained from creep tests and the stress exponent of steady-state creep rate is about 7 characteristic of the sintered materials in which subgrains do not form during creep. The ratio of the activation energy for steady-state creep to the lattice diffusion energy is then calculated to be less than 0.5, which may result from the active short-circuit diffusion through many boundaries of fibers in the present material.
