ドープタングステン細線の高温クリープ中のしきい応力に及ぼすカリウム濃度の影響

抄録

It is investigated how sliding and cavitation at grain boundaries have an effect on the measurement of threshold stress σ_T. The effect of the potassium concentration on σ_T is then clarified under the condition that such effects resulting from grain boundaries are almost negligible. The flow stresses and the hardness of grain interiors, which are obtained at high and room temperatures, respectively, using tungsten fine wires of secondary recrystallized grains arranged in a simple morphology, increase with increasing potassium concentration. It is shown that if grain morphology is arranged in a way that makes it free from grain boundary sliding and cavitation, the threshold stress can be measured by abrupt stress change tests during creep and increases with potassium concentration. However, it is also noted that the effect of σ_T on the creep rate is much less than that caused by the change of grain morphology.