POSITRON-ANNIHILATION STUDY OF DISLOCATIONS PRODUCED BY POLISHING IN THE SURFACE OF IRON SINGLE-CRYSTALS - .1. DENSITY PROFILE AND REMOVAL BY ANNEALING
POSITRON-ANNIHILATION STUDY OF DISLOCATIONS PRODUCED BY POLISHING IN THE SURFACE OF IRON SINGLE-CRYSTALS - .1. DENSITY PROFILE AND REMOVAL BY ANNEALING
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DOI：
10.1007/bf02647251
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发表时间：
1990-07-01
期刊：
影响因子：
--
通讯作者：
WABER, JT
中科院分区：
文献类型：
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作者：
LEE, JL;WABER, JT
本文用正电子多普勒展宽方法研究了铁单晶中陷阱浓度与磨损表面深度的关系。在240粒度的SiC砂纸上进行机械抛光时，试样表面的变形深度约为40 μm。当使用0.3 μ mAl_（1 - 2）O_3颗粒浆料时，损伤区深度小于15 μm。在变形层中发现刃位错和螺位错的混合物。机械抛光铁退火后观察到的两个阶段的恢复被解释为是由于在较低的温度退火（273至473 K）的螺钉组件的消失。当螺型位错的数量显著减少时，边缘位错偶极子开始消失。螺位错和刃位错的恢复的激活能估计为30.5和103.2 kJ/mol，分别使用二阶Li模型。基于这些小的能量，纯铁中的位错偶极子通过滑移而不是通过攀移而消失。单空位的迁移和爬升显然是重要的不纯铁，因为激活能是类似的空位迁移。
The trap concentration as a function of the depth from the abraded surface of iron single crystals was investigated by means of positron Doppler broadening. The deformation depth was about 40 μm from the surface when the specimen was mechanically polished on 240-grit SiC paper. The depth of the damaged region is less than 15 μm from the surface when a slurry of 0.3 /xm A1"2O3particles is used. A mixture of edge and screw dislocations was found in the deformed layer. The two stages in recovery observed upon annealing mechanically polished iron are interpreted as being due to the disappearance of screw components during lower temperature anneals (273 to 473 K). When the number of screw dislocations has fallen considerably, the edge-dislocation dipoles begin to disappear. The activation energies for recovery of screw and edge dislocations are estimated at 30.5 and 103.2 kJ/mol, respectively, using the second-order Li model. Based on these small energies, dislocation dipoles disappear by glide rather than by climb in pure iron. Migration of monovacancies and climb are apparently important with impure iron, since the activation energy is similar to that for vacancy migration.