Atomic-scale computer simulation for early precipitation process of Ni_(75) Al_x V_(25-x) alloy with intermediate Al composition  

作　　者：ZHAOYuhong JUDongying CHENZheng HOUHua 

机构地区：[1]CollegeofMaterialScience＆Engineering,ChinaNorthUniversity,Taiyuan030051,China [2]DepartmentofMechanicalEngineering,SaitamaInstituteofTechnology,Okabe,Saitama3690239,Japan [3]ColledgeofMaterialsScience＆Engineering,North-westernPolytechnicalUniversity,Xi＇an710072,China

出　　处：《Progress in Natural Science:Materials International》2005年第4期351-357,共7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 microscopic phase-field approach is applied to model the early precipitation process of Ni75AlxV25-x alloy. Without any prior assumptions, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. By simulating the atomic pictures, and calculating the order parameters and volume fraction of the theta(Ni3V) and gamma'(Ni3Al) ordered phases, we study Ni75AlxV25-x alloys with Al composition of 0.05, 0.053 and 0.055 (atom fraction). Our calculated results show that, for these alloys, theta and gamma' phases precipitate at the same time; with the increase of Al content, the amount of gamma' phase increases and that of theta phase decreases; the precipitation characteristic of gamma' phase transforms from Non-Classical Nucleation and Growth (NCNG) to Congruent Ordering + Spinodal Decomposition (CO + SD) gradually; otherwise, the precipitation characteristic of theta phase transforms from Congruent Ordering + Spinodal Decomposition (CO + SD) to Non-Classical Nucleation and Growth (NCNG) mechanism gradually. Both theta and gamma' phases have undergone the transition process of mixture precipitation mechanism characterized by both NCNG and CO + SD mechanisms. No incontinuous transition of precipitation mechanism has been found.The microscopic phase field approach is applied to model the early precipitation process of Ni 75 Al x V 25- x alloy. Without any prior assumptions, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. By simulating the atomic pictures, and calculating the order parameters and volume fraction of the θ (Ni 3V) and γ′ (Ni 3Al) ordered phases, we study Ni 75 Al x V 25- x alloys with Al composition of 0.05, 0.053 and 0.055 (atom fraction). Our calculated results show that, for these alloys, θ and γ′ phases precipitate at the same time; with the increase of Al content, the amount of γ′ phase increases and that of θ phase decreases; the precipitation characteristic of γ′ phase transforms from Non Classical Nucleation and Growth (NCNG) to Congruent Ordering + Spinodal Decomposition (CO+SD) gradually; otherwise, the precipitation characteristic of θ phase transforms from Congruent Ordering + Spinodal Decomposition (CO+SD) to Non Classical Nucleation and Growth (NCNG) mechanism gradually. Both θ and γ′ phases have undergone the transition process of mixture precipitation mechanism characterized by both NCNG and CO+SD mechanisms. No incontinuous transition of precipitation mechanism has been found.

关 键 词：computer simulation early precipitation mechanism phase field model Ni75AlxV25-x alloy 

分 类 号：TG146.15[一般工业技术—材料科学与工程]