Zr-4合金应力松弛过程中的热激活变形与动态应变时效

THERMALLY ACTIVATED DEFORMATION AND DYNAMIC STRAIN AGING OF Zr-4 ALLOY DURING STRESS RELAXATION

采用应力松弛实验研究了Zr-4合金的热激活变形与动态应变时效现象.结果表明,合金在应力松弛过程中的塑性变形速率随松弛时间的增加而减小,塑性变形速率和松弛结束时的应力降低比率在623 K附近都会出现最小值.对位错运动的激活体积分析发现,锆合金中位错运动的速率控制机制是位错克服溶质原子的障碍,动态应变时效会导致位错运动的激活体积增大, 623 K附近动态应变时效最为显著,位错密度会对合金的动态应变时效产生影响.

The thermally activated deformation and dynamic strain aging （DSA） of Zr-4 were investigated by stress relaxation experiments in a broad temperature range. It is found that in the process of stress relaxation, the plastic deformation rate of the alloy decreases with the relaxation time, and this rate and the stress reduction ratio at the end of relaxation exhibit a minimum value at about 623 K. The activation volume associated with dislocation motion is found from the relationship between the stress and relaxation time. A noticeable maximum value appears around 623 K when the activation volume plotted against the temperature, which suggests that at this temperature, DSA is most pronounced. The strain dependence of the activation volume is analyzed. The rate control- ling deformation mechanism is identified as the overcoming of solute atoms by dislocations, and the dislocation density is found to have an influence on DSA.