电脉冲处理下疲劳铜单晶的再结晶

RECRYSTALLIZATION OF FATIGUED COPPER SINGLE CRYSTALS UNDER ELECTROPULSING

对疲劳后的［１２３］铜单晶体进行高电流密度脉冲处理可以形成多边形与椭同形两种再结晶晶粒、晶粒尺寸分别为７．２－８．８μｍ和５．３－８．０μｍ．高电流密度脉冲处理造成的位错湮没会增大局部位错分布不均匀区域的位错密度梯度．从而形成再结晶的晶核． 由于脉络结构分布均匀，在这一区域形成的再结晶晶粒没有明显的方向性．而在驻留滑移带处形成的再结晶晶粒，由于位错的运动在平行于 Ｂｕｒｇｅｒｓ矢量的方向容易进行，因此形成的再结晶品粒的尺寸沿这一方向要大一些， 在驻留滑移带处由脉冲电流处理引起的局部温升． 增加了位错运动的可能性，导致再结晶晶粒之间间隔一定距离 ，由于电脉冲作用时间很短，晶粒没有足够的时间长大，从血形成晶粒尺寸较小的再结晶晶粒．

Fatigued copper single crystal with [123] loading axis was treated by high current density electropulsing. and formed two kinds of recrystallized grains with polygonal shape and 7.2-8.8 mum in size, and with ellipsoidal shape and 5.3-8.0 mum in size. The annihilation of dislocations caused by high current electropulsing increases the dislocation density gradient over which local inhomogeneous dislocation structures promotes the formation of recrystallized nuclei. Due to the homogeneous distribution of the vein structures, the recrystallized grains around this region do not process a specific directionality. On the other hand, the recrystallized grains formed around persistent slip bands show bigger grain sizes along the direction parallel to Burgers vector presumably due to the dislocations motion being easier along this direction. The higher temperature rise in persistent slip bands caused by electropulsing than in vein structure increases the possibility of dislocations motion, and leads to the existence of sonic distances between recrystallized grains. Because of the very short treating time under high current elect repulsing, the grains have no enough time to grow, and so the recrystallized grains are of finer sizes.