抄録
Stress relaxation and creep tests were carried out to estimate the dislocation velocity-stress exponents (m* and m) for nominally pure KCl single crystals deformed in cube orientation at high temperatures (150°C to 680°C) and at room temperature. The stress and strain rate cycling tests were also applied. It was found that the m-value at high temperatures was about 8 to 10 from the measurements under relatively low applied stress, but it increased sharply when the applied stress exceeded about 0.5kg/mm2. The m*-value obtained by stress relaxation was always lower than the corresponding m-value in accordance with the theory of Nix et al. The stress relaxation at room temperature indicated that the power law approach of Johnston and Gilman (1959) is no more valid at room temperature. The effect of friction between sample and jig faces was also discussed. It is considered that the stress exponents can be material constants if sufficient care is taken for measurement.
