Atomic-scale computer simulation for early precipitation process of Ni_(75) Al_(10) V_(15) alloy  

作　　者：ZHAOYuhong CHENZheng WANGYongxin LUYanli 

机构地区：[1]DepartmentofMaterialsScienceandEngineering,NorthwesternPolytechnicalUniversity,Xi＇an710072,China [2]DepartmentofMaterialsScienceandEngineering,NorthwesternPolytechnicalUniversity,Xi＇an710072,China

出　　处：《Progress in Natural Science:Materials International》2004年第3期241-246,共6页自然科学进展·国际材料（英文版）

基　　金：SupportedbytheNationalNaturalScienceFoundationofChina (GrantNo .5 0 0 710 46)

摘　　要：The kinetic model for a ternary system is introduced based on the microscopic diffusion form of the phase field equations for a binary alloy. The equation is solved in the reciprocal space. This model is used to investigate the early precipitation process of Ni 75 Al 10 V 15 by simulating the atomic pictures of the two ordered phases and calculating the order parameters of γ ′(Ni 3Al) phase. Simulation results show that the γ ′ ordered phases precipitate from the disordered matrix by a non classical nucleation mechanism, and the nonstoichiometric γ ′ ordered phase appears first and then transforms into the stoichiometric one. Clusters of V atoms appear at the γ ′ phase boundaries followed by the formation of the nonstoichiometric θ ordered phase. The farther the location from γ ′ phase boundary is, the lower the order degree of θ phase is. There exist two kinds of DO 22 ordered domains: a horizontal one and a vertical one, related to their adjacent γ ′ phase boundaries. The model could describe the atomic ordering and composition clustering simultaneously, and any a priori assumption about the new phase structure and precipitation mechanism etc. is unnecessary.The kinetic model for a ternary system is introduced based on the microscopic diffusion form of the phase field equations for a binary alloy. The equation is solved in the reciprocal space. This model is used to investigate the early precipitation process of Ni 75 Al 10 V 15 by simulating the atomic pictures of the two ordered phases and calculating the order parameters of γ ′(Ni 3Al) phase. Simulation results show that the γ ′ ordered phases precipitate from the disordered matrix by a non classical nucleation mechanism, and the nonstoichiometric γ ′ ordered phase appears first and then transforms into the stoichiometric one. Clusters of V atoms appear at the γ ′ phase boundaries followed by the formation of the nonstoichiometric θ ordered phase. The farther the location from γ ′ phase boundary is, the lower the order degree of θ phase is. There exist two kinds of DO 22 ordered domains: a horizontal one and a vertical one, related to their adjacent γ ′ phase boundaries. The model could describe the atomic ordering and composition clustering simultaneously, and any a priori assumption about the new phase structure and precipitation mechanism etc. is unnecessary.

关 键 词：early precipitation process computer simulation Ni    75  Al    10  V    15   alloy. 

分 类 号：TG146.15[一般工业技术—材料科学与工程] TG146.413[金属学及工艺—金属材料]