Microscopic phase-field simulation coupled with elastic strain energy for precipitation process of Ni-Cr-Al alloys with low Al content  

作　　者：卢艳丽 陈铮 李永胜 王永欣 

机构地区：[1]School of Materials Science and Engineering,State Key Laboratory of Solidification Processing, Northwestern Polytechnical University

出　　处：《中国有色金属学会会刊：英文版》2007年第1期64-71,共8页Transactions of Nonferrous Metals Society of China

基　　金：Projects(50671084,50071046)supported by the National Natural Science Foundation of China;Project(2002AA331051)supported by the National Hi-Tech Research Development Program of China

摘　　要：The precipitation process of Ni-Cr-Al alloy with low Al content was studied at atomic scale based on the microscopicphase-field kinetic model coupled with elastic strain energy.The aim is to investigate the effect of elastic strain energy onprecipitation mechanism and morphological evolution of the alloy.The simulation results show that in the early stage of precipitation,D022 phase and L12 phase present irregular shape,and they randomly distribute in the matrix.With the progress of aging,L12 phaseand D022 phase change into the quadrate shape and their orientations become more obvious.In the later stage,L12 phase and D022phase present quadrate shape with round corner and align along the[100]and[010]directions,and highly preferential selectedmicrostructure is formed.The mechanism of early precipitation of L12 phase in Ni-17%Cr-7.5%Al(mole fraction)alloy is the mixedstyle of non-classical nucleation growth and spinodal decomposition and the D022 phase is the spinodal decomposition.Themechanisms of early precipitation of L12 phase and D022 phase in Ni-12.5%Cr-7.5%Al alloy are both the non-classical nucleationand growth.The coarsening process follows the rule of preferential selected coarsening.The precipitation process of Ni-Cr-Al alloy with low Al content was studied at atomic scale based on the microscopic phase-field kinetic model coupled with elastic strain energy. The aim is to investigate the effect of elastic strain energy on precipitation mechanism and morphological evolution of the alloy. The simulation results show that in the early stage of precipitation, D022 phase and Ll2 phase present irregular shape, and they randomly distribute in the matrix. With the progress of aging, Ll2 phase and D022 phase change into the quadrate shape and their orientations become more obvious. In the later stage, Ll2 phase and D022 phase present quadrate shape with round corner and align along the [100] and [010] directions, and highly preferential selected microstructure is formed. The mechanism of early precipitation of Ll2 phase in Ni-17%Cr-7.5%Al （mole fraction） alloy is the nfixed style of non-classical nucleation growth and spinodal decomposition and the D022 phase is the spinodal decomposition. The mechanisms of early precipitation of L 12 phase and D022 phase in Ni-12.5%Cr-7.5% Al alloy are both the non-classical nucleation and growth. The coarsening process follows the rule of preferential selected coarsening.

关 键 词：弹性应变能量 合金 镍 铝 沉淀作用 

分 类 号：TG115[金属学及工艺—物理冶金]