共查询到20条相似文献,搜索用时 62 毫秒
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The structure and the migration mechanisms of
twin boundaries (TBs) of pure zinc deformed by rolling were studied using high-resolution transmission electron microscopy (HRTEM) at atomic scale. We found the presence of basal/prismatic (BP/PB) planes serrations on
TBs and the coexistence of two kinds of TBs with different structures in the same
twin: TBs composed of
coherent twin boundaries (CTBs) plus short BP/PB serrations, and TBs composed of successive BP/PB segments without
CTBs. The formation of BP/PB serrations has no relation to the c/a ratio of hexagonal-close-packed (HCP) metals because the BP/PB serrations are energetically preferred and geometrically favored. Based on dislocation theory, we proposed the migration mechanisms of the TBs to be the glide of twinning dislocations (TDs) on the CTBs and the climb of interface dislocations (IDs) on the BP/PB segments. 相似文献
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Na LIU Ying WANG Wei-jun HE Jun LI Adrien CHAPUIS Bai-feng LUAN Qing LIU 《中国有色金属学会会刊》2018,28(6):1123-1131
The effects of cold rolling and annealing on the microstructure and textural evolution of a commercially pure titanium (CP-Ti) sheet were investigated. Electron backscatter diffractometry demonstrates that the deformation during rolling is accommodated by twinning and slip. Additionally, twinning is the dominant deformation mechanism when the cold rolling reduction is less than 40%. During rolling,
contraction twinning (CT) and
extension twinning (ET) are activated. And, the intensity of the (0002) pole along the ND gradually increases with increasing deformation. During annealing, the fraction of low angle grain boundaries (LAGBs) and the intensity of the (0002) pole along the ND gradually decrease slightly with increasing annealing time, while twinning lamellae disappear rapidly. When the annealing time reaches 60 min, 20% cold-rolled sheet recrystallizes almost completely. 相似文献
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Yi-lan JIANG Hui-qun LIU Dan-qing YI Gao-yong LIN Xun DAI Rui-qian ZHANG Yong-duo SUN Shao-qiang LIU 《中国有色金属学会会刊》2018,28(4):651-661
The effects of cold-rolling reduction, annealing temperature, and time on recrystallization behavior and kinetics of cold-rolled Zr-1Sn-0.3Nb-0.3Fe-0.1Cr alloy were investigated using the Vickers hardness test, scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and electron backscatter diffractometry (EBSD). The results show that the rate of the recrystallization increased with increasing annealing temperature and rolling reduction. Recrystallized grains nucleated preferentially at sites with high density dislocation and deformation stored energy and then grew into integral grains. Recrystallization texture changed from
//RD to
//RD. The grain orientation changed from random orientation to the orientation with the maximum misorientation around 30°. Recrystallization kinetics and maps were constructed based on the Johnson–Mehl– Avrami–Kolmogorov (JMAK) equation to derive parameters sensitive to the microstructure. The activation energies for recrystallization of 30%, 50% and 70% cold-rolling reductions were determined to be 240, 249 and 180 kJ/mol, respectively. 相似文献
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Fang Cao Irene J. Beyerlein Francis L. Addessio Bulent H. Sencer Carl P. Trujillo Ellen K. Cerreta George T. Gray III 《Acta Materialia》2010,58(2):549-559
Shock recovery experiments have been conducted to assess the role of shock stress and orientation dependence on substructure evolution and deformation twinning of a [1 0 0]/ copper bicrystal. Transmission electron microscopy of the post-shock specimens revealed that well-defined dislocation cell structures developed in both grains and the average cell size decreased with increasing shock pressure from 5 to 10 GPa. Twinning occurred in the [1 0 0] grain, but not the grain, at the 10 GPa shock pressure. The stress and orientation dependence of incipient twinning can be predicted by the stress and orientation conditions required to dissociate slip dislocations into glissile twinning dislocations. The dynamic widths between the two partials are calculated considering the three-dimensional deviatoric stress state induced by the shock as calculated using plane-strain plate impact simulations and the relativistic and drag effects on dislocations moving at high speeds. 相似文献
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《Acta Materialia》2005,53(13):3625-3634
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将具有随机初始织构的工业 AZ91镁合金在450°C 进行均匀化热处理。经热处理后,合金中出现弱的{0001}-{1010}-{1120}三重纤维织构。经400°C热轧后,合金的变形织构是典型的(0001)基面,其基极沿轧制方向分裂。在450°C 退火36 h后,其残余变形织构中的基极沿基面分布更均匀,没有出现晶粒的异常长大。 相似文献
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