Qiang LI
,
Yongbo XU
,
Zuhan LAI
,
Letian SHEN
,
Yilong BAI
材料科学技术（英文）
Recrystallized grains, less than 200 nm in diameter were observed in heavily shear zones of a high strength low alloy steel and a Ni-based alloy, and Also grain refinement, less than 3 μm in diameter was made in high purity aluminum by ECAE at ambient temperature. The experimental results showed that high strain rate and large deformation could induce dynamic recrystallization. Based on dislocation dynamics and grain orientation change enhanced by plastic deformation, a model for the recrystallization process is developed. The model is used to explain the ultra fine grains which are formed at a temperature still much lower than that for the conventional recrystallization.
关键词:
姜威
,
刘廷禹
,
孙颖
,
孙羽
人工晶体学报
基于密度泛函理论平面波赝势法对LaBr3晶体本征点缺陷进行了系统研究.通过第一性原理和热动力学方法,计算得到了不同温度及溴分压下LaBr3晶体中本征点缺陷的缺陷形成能,并讨论了不同环境条件下本征点缺陷的形成能随费米能级的变化关系.计算结果表明,当费米能级位于导带底附近时,LaBr3晶体中的主要点缺陷为Lai…能级位于价带顶附近时,LaBr3晶体中主要的点缺陷为Vlao…VBr在高温/低溴分压相对稳定,Vla在低温/高溴分压更稳定.本文还做出了最稳定点缺陷随温度、溴分压及费米能级变化的三维空间分布图,清晰地呈现了不同条件下,该晶体最可能出现的点缺陷类型,从而为调控晶体的点缺陷改善晶体光学性能提供参考.
关键词:
LaBr3晶体
,
密度泛函理论
,
点缺陷
,
热力学
