The effect of gas bubbles on the high-temperature creep of doped tungsten wires

The high-temperature creep behaviour of recrystallized AKS-doped tungsten wires has been investigated as function of grain size, grain aspect ratio, and bubble size over a range of temperatures 3000-3500 K for stresses lower than 10-4G (where G is shear modulus). Electron microscopic evidence is presented that, in addition to an indirect bubble contribution to the creep resistance through the control of grain parameters, the creep strength of doped tungsten wires, corresponding to the experimentally observed high activation energy and low stress dependence of the minimum creep rate, is determined by strong dislocation-bubble interactions which depend on the critical bubble size. (author)