In在Al(001)表面偏析的模拟  

Simulation of surface segregation of in to Al(001) surface

作　　者：刘建才[1] 张新明[1] 陈明安[1] 唐建国[1] 刘胜胆[1] 

机构地区：[1]中南大学材料科学与工程学院有色金属材料科学与工程教育部重点实验室,长沙410083

出　　处：《物理学报》2010年第8期5641-5645,共5页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2005CB623706)资助的课题~~

摘　　要：通过一种空位模型详细的描述了In在Al(001)表面的扩散偏析过程,利用周期性密度泛函理论方法计算了这个偏析过程中每步构型的能量和In原子扩散的能量壁垒,并对可能的偏析机理进行分析.结果表明:In原子从Al(001)表面第二层扩散偏析至表面层时,系统的能量降低了0.64eV,最大的扩散迁移壁垒为0.34eV;而从表面更内层向表面第二层扩散时系统能量基本保持不变,扩散需要克服的能量壁垒为0.65eV,说明In原子在Al(001)表面只能由体内向表面扩散偏析.In在Al(001)的清洁表面具有强烈的偏析趋势,在热力学上是容易进行的.A new vacancy model by using periodic density functional theory was used to describe the process of In segregation from clean Al surfaces via atomic movement through vacancies. The detailed segregation mechanism of impurity metal In to Al （001） surface planes is examined,carefully evaluating energy barriers for each step in the segregation process. The results show that the system energy is decreased by 0. 46 eV and the highest energy barrier is 0. 34 eV when the impurity atom In moves from the second layer to the topmost layer in the Al （001） slab. The system energy is almost constant when impurity atoms segregate from the third layer to the second layer. Higher energy （0. 65 eV） was needed to overcome the energy barriers. So,In showing a strong segregation to the clean Al （001） surface is thermodynamically favorable.

关 键 词：密度泛函理论 表面偏析 扩散 AL合金 

分 类 号：TG111[金属学及工艺—物理冶金]