疲労転位組織の安定性に関する原子・転位論的考察

抄録

The stability of persistent slip band（PSB）at the submicron meter scale is investigated through molecular dynamics simulations. The PSB model includes grain boundaries in the direction of the dislocation line within the dislocation wall. Here, the special attention is paid to the “stability of the dislocation wall microstructure” and the “interaction between the screw dislocations moving in the channel and the grain boundary”. It is found that PSB cannot exist stably when the dimensions are small（for example, the channel distance is 60 nm）. Grain boundary is strong absorption site for channel screw dislocation, and once a screw dislocation is absorbed, it is difficult for it to be re-emitted. The operating stress and the re-emission stress of channel screw dislocation are greater than the collapse stresses of dislocation walls. As a result, the stability of PSB strongly depends on the plastic deformation ability of the screw dislocations in the channel in addition to the channel spacing. If the screw dislocations penetrate the grain boundary and are unable to relax plastically within the channel, the dislocation wall may collapse prematurely, suggesting that the formation of PSB in ultrafine-grained materials will be difficult.