选用经多向锻造和再结晶退火的晶粒组织均匀(平均晶粒尺寸为20 μm)且取向均匀的高纯Al (99.99%)为原料, 将2组平行样品分别进行等效应变ε≈2的等径角挤压(ECAP)和单向轧制(DR)变形后, 再经360 ℃再结晶退火8~90 min, 利用基于体视学原理和电子背散射衍射技术(EBSD)的五参数分析法 (FPA) 对比研究了不同变形方式对高纯Al退火再结晶晶界面取向分布的影响. 结果表明, 经变形及360 ℃退火后, 2组样品中其再结晶晶界面主要取向于低能稳定的{111}, 并主要对应于以<111>为转轴的大角度扭转晶界. ECAP与DR样品退火后的主要差异在于, 前者再结晶晶界面取向于{111}的过程较迟缓; 后者再结晶晶界面比较容易取向于{111}. 分析指出, DR变形更容易使高纯Al再结晶晶面取向于低能稳定的{111}, 更有益于晶界特征分布的优化. 这与DR变形形成的<110>//ND织构导致其再结晶退火过程中晶粒容易长大有关.
It is quite different from those low to medium stacking fault energy face-centered cubic metals, Al and most its alloys are not applicable to twin-induced grain boundary engineering processing due to their high stacking fault energy. In order to optimize the grain boundary character distribution so as to remarkably better the properties of Al and its alloys, it is necessary at first to study the grain boundary plane distributions. In this work, two parallel high purity (99.99%) Al specimens, which were prepared by multi-directional forging followed by recrystallization annealing resulting in a homogeneous microstructure with averaged grain size around 20 μm, were separately processed by equal channel angular pressing (ECAP) and direct rolling (DR) with true strain ε≈2 followed by a recrystallization annealing at 360 ℃ for 8~90 min. Then, the grain boundary plane distributions were characterized by five-parameter analysis (FPA) based on stereology method and electron backscatter diffraction (EBSD). The results show that the grain boundary planes of the specimens as processed mainly orient on {111}, mostly corresponding to the <111> twist high angle boundaries. It is due to the energy minimum of {111}. The primary difference of grain boundary plane distributions between ECAP and DR specimens lies in the behaviors of grain boundary planes orienting onto {111}. For ECAP specimens, it is slow the grain boundary planes orienting onto {111}. However, for DR specimens, it is quite easy the grain boundary planes orienting onto {111}. Discussions pointed out, compared with ECAP deformation, DR deformation is more efficient for grain boundary plane orienting onto {111} in the subsequent recrystallization annealing and thus is more in favor of the optimization of grain boundary character distribution. It could be attributed to the development of <110>//ND textures during DR deformation which results in the fast grain growth in the subsequent recrystallization annealing.
参考文献
| [1] |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%