Oh Jin-Su, Cha Hyun-Woo, Kim Tae-Hoon, Shin Keesam, Yang Cheol-Woong
School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, South Korea.
Ames Laboratory, U.S. Department of Energy, Ames, Iowa.
Microsc Res Tech. 2019 Jun;82(6):849-855. doi: 10.1002/jemt.23226. Epub 2019 Jan 28.
Study on recrystallization of deformed metal is important for practical industrial applications. Most of studies about recrystallization behavior focused on the migration of the high-angle grain boundaries, resulting in lack of information of the kinetics of the low angle grain boundary migration. In this study, we focused on the migration of the low angle grain boundaries during recrystallization process. Pure nickel deformed by shot peening which induced plastic deformation at the surface was investigated. The surface of the specimen was prepared by mechanical polishing using diamond slurry and colloidal silica down to 0.02 μm. Sequential heat treatment under a moderate annealing temperature facilitates to observe the migration of low angle grain boundaries. The threshold energy for low angle boundary migration during recrystallization as a function of misorientation angle was evaluated using scanning electron microscopy techniques. A combination of electron channeling contrast imaging and electron backscatter diffraction was used to measure the average dislocation density and a quantitative estimation of the stored energy near the boundary. It was observed that the migration of the low angle grain boundaries during recrystallization was strongly affected by both the stored energy of the deformed matrix and the misorientation angle of the boundary. Through the combination of electron channeling contrast imaging and electron backscatter diffraction, the threshold stored energy for the migration of the low angle grain boundaries was estimated as a function of the boundary misorientation.
变形金属再结晶的研究对于实际工业应用具有重要意义。大多数关于再结晶行为的研究都集中在大角度晶界的迁移上，导致缺乏小角度晶界迁移动力学的信息。在本研究中，我们关注再结晶过程中小角度晶界的迁移。研究了通过喷丸处理使表面产生塑性变形的纯镍。试样表面使用金刚石研磨液和胶体二氧化硅进行机械抛光，直至达到0.02μm。在适度退火温度下进行顺序热处理有助于观察小角度晶界的迁移。使用扫描电子显微镜技术评估了再结晶过程中小角度晶界迁移的阈值能量与取向差角的函数关系。结合电子通道衬度成像和电子背散射衍射来测量平均位错密度，并对晶界附近的储能进行定量估计。研究发现，再结晶过程中小角度晶界的迁移受到变形基体的储能和晶界取向差角的强烈影响。通过结合电子通道衬度成像和电子背散射衍射，估计了小角度晶界迁移的阈值储能与晶界取向差的函数关系。
