Cu单晶中疲劳早期位错花样演化的观察与模拟

OBSERVATION AND SIMULATION OF DISLOCATION PATTERN EVOLUTION IN THE EARLY STACES OF FATICUE IN A COPPER SINGLE CRYSTAL

采用离散的位错动力学方法，用计算机模拟循环形变单滑移取向Ｃｕ单晶中疲劳早期位错花样的形成和演化过程，并利用扫描电镜电子通道衬度（ＳＥＭ—ＥＣＣ）技术对其进行了观察．计算机模拟结果与实验观察较好地吻合．提出了在循环形变早期位错脉络的形成和演化是从同号的基体位错墙开始的，基体偶极子位错墙是两个异号基体位错墙合并的结果，在偶极子位错墙破碎并演化为基体脉络的过程中螺型位错段起到了重要作用等观点。

During cyclic deformation, the dislocation pattern formed at the early stages and its evolution were simulated by using the method of discrete dislocation dynamics and observed with the electron channeling contract (ECC) technique in scanning electron microscopy (SEM) on a single-slip- oriented copper single crystals. Computer simulation results agress rather well with the experimental observations. Hence, some new mechanisms were proposed. Such as in the early stages of cyclic deformation, the dislocation vein formation and evolution could originate from the matrix walls which are composed by the same sign of dislocations, and a dipole matrix wall could be formed by combining two matrix walls with opposite sign of dislocation. Also it is confirmed that screw dislocation segments play an important role during the process that the dipole matrix walls fragmeatize and evolve into matrix vein structure.