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对两种晶粒尺寸的99.999％高纯Al试样,经充分退火后,在不同形变温度和不同应变速率下,进行小应变静拉伸试验,结果表明,提高温度和降低应变速率均有助于减小形变硬化。使用光学显微镜和透射电子显微镜观察了形变后晶界及其邻近区域的状态,确定了温度及应变速率是控制晶界吸收、放出及阻碍位错运动的重要因素。并指出在小应变范性形变中,晶界与位错的交互作用机制是形变条件影响宏观力学性能的重要原因,晶粒尺寸是这一交互作用强度的度量。本文推导了形变硬化系数A与变形温度、应变速率和晶粒尺寸之间的函数关系式,根据实验数据作了回归计算,求得晶界吸收位错的激活能为0.35eV。
For the two kinds of grain size of 99.999% high purity Al samples, after fully annealed, the small strain static tensile test was carried out under different deformation temperatures and different strain rates. The results showed that both increasing the temperature and decreasing the strain rate To reduce the deformation hardening. The state of the grain boundary and its adjacent area after deformation was observed by optical microscope and transmission electron microscope. The temperature and strain rate were determined to be important factors controlling the absorption, release and dislocation movement of the grain boundaries. It is also pointed out that the interaction mechanism between grain boundaries and dislocations is the important reason that the deformation conditions affect the macroscopic mechanical properties. The grain size is a measure of the strength of this interaction. In this paper, the functional relationship between the strain hardening coefficient A and deformation temperature, strain rate and grain size is derived. Based on the experimental data, the activation energy is 0.35eV.