分散強化型Al-Be合金の高温クリープにおける加工硬化率と回復速度

Abstract

Work hardening and recovery during high temperature creep of aluminum strengthened by dispersed beryllium particles have been investigated by means of the stress relaxation method. It was found that the proportion of the internal stress to the flow stress is nearly 100 percent and hence that the deformation is governed by a recovery process. Under the chosen condition of stress and temperature (10−4≤σ⁄E≤10−3, 0.51≤Tm⁄T≤0.69), the work hardening rate, h, showed no dependence on temperature and increased only slightly with an increase in stress. The recovery rate, r, is related to stress and temperature by(This article is not displayable. Please see full text pdf.) \ oindentHere the stress exponent, nr (9.5∼10.0), is close to that for the steady-state creep rate and the activation energy for recovery, Qr (138∼152 kJ/mol), is in agreement with that for volume self-diffusion in pure aluminum. The results are in contrast to those reported for pure aluminum in which h depends both on stress and temperature and the temperature dependence of r does not agree with that of volume self-diffusion, suggesting that the recovery in Al-Be alloys may be controlled by a unique thermally activated process. It is also shown that the effect of interparticle spacing on the work hardening rate is much smaller than that on the recovery rate, and hence that the increase in creep strength is brought about by the decrease in the recovery rate.