Microscopic Phase-field Simulation of Effects of Re-ageing Temperature on Precipitation of Ni-Al-Cr Alloys  

作　　者：Zhang Jixiang Chen Zheng Lai Qingbo Zhao Yan Wang Yongxin 

机构地区：[1]School of Materials Science and Engineering, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China [2]School of Materials Engineering, Yancheng Insititute of Technology, Yancheng 224051, China

出　　处：《Chinese Journal of Aeronautics》2009年第5期551-557,共7页中国航空学报（英文版）

基　　金：Foundation items： National Natural Science Foundation of China （50671084）; China Postdoctoral Science Foundation Funded Project （20070420218）

摘　　要：This article, by means of the ternary microscopic phase-field model, investigates the effects of re-ageing temperature on the precipitation of Ni75Al10Cr15 alloy with the help of atomic pictures, order parameters, particle density, averaged radii, and volume fractions. During pre-ageing at 873 K, DO22 phases first appear through spinodal decomposition mechanism, and then L12 phases begin to form on the DO22 phase-boundaries through non-classical nucleation mechanism. In either of them, ordering process is obviously faster than atom clustering. At the late stage of re-ageing at 923 K, the elastic strain energy seems to exert stronger effects on microstructure, and DO22 and L12 phases exhibit directional alignment along 〈100〉 direction to a certain extent. When the temperature increases to 1 023 K, the influence of elastic strain energy begins to weaken, and the precipitated phases become randomly distributed in the matrix. The volume fraction of DO22 phase decreases to zero, whereas that of L12 phase first increases and then decreases with the temperature rising from 923 K to 1 123 K. On the whole, the effects of elastic strain energy make the coarsening behavior of both phases deviate from the time-law predictions by LSW diffusion-controlled growth theory.This article, by means of the ternary microscopic phase-field model, investigates the effects of re-ageing temperature on the precipitation of Ni75Al10Cr15 alloy with the help of atomic pictures, order parameters, particle density, averaged radii, and volume fractions. During pre-ageing at 873 K, DO22 phases first appear through spinodal decomposition mechanism, and then L12 phases begin to form on the DO22 phase-boundaries through non-classical nucleation mechanism. In either of them, ordering process is obviously faster than atom clustering. At the late stage of re-ageing at 923 K, the elastic strain energy seems to exert stronger effects on microstructure, and DO22 and L12 phases exhibit directional alignment along 〈100〉 direction to a certain extent. When the temperature increases to 1 023 K, the influence of elastic strain energy begins to weaken, and the precipitated phases become randomly distributed in the matrix. The volume fraction of DO22 phase decreases to zero, whereas that of L12 phase first increases and then decreases with the temperature rising from 923 K to 1 123 K. On the whole, the effects of elastic strain energy make the coarsening behavior of both phases deviate from the time-law predictions by LSW diffusion-controlled growth theory.

关 键 词：Ni-Al-Cr alloy microscopic phase-field RE-AGEING NUCLEATION order parameter 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TS972.1[金属学及工艺—金属材料]