Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第14卷    第2期    总第59期    2004年2月

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文章编号:1004-0609(2004)02-0255-07
δ′相在外场下早期沉淀机制的计算机模拟
王永欣, 陈  铮, 刘 兵, 马 良, 唐丽英, 赵宇宏

(西北工业大学 材料科学与工程学院, 西安 710072)

摘 要: 基于离散格点形式的微扩散方程(Langevin方程)和非平衡自由能函数, 编制了引入原子间相互作用能变化的Al3Li(δ′)相沉淀原子层面计算机模拟程序。 该程序包容亚稳区到失稳区的全部温度、 成分范围和孕育期至粗化的全过程,可以处理与时间相关的过程问题。 开展了不同原子间相互作用势下原子图像、 序参数的计算机模拟, 进而探讨了最近邻原子相互作用能(W1)对有序相沉淀的影响机制。 发现过渡区合金形核前出现短暂的等成分有序化阶段。探明随W1的增大, 有序相沉淀的孕育期缩短,形核率增加, 合金有序化速度和原子簇聚速度加快, 在所研究的时间范围内达到的长程序参数和成分偏离序参数最大值增大。 随W1的增大, 有序相的析出呈现出失稳分解的特征。

 

关键字: 原子间相互作用势; 沉淀; 原子图像; 序参数; 计算机模拟

Computer simulation on precipitation mechanism of δ′ phase in early stage in external energy field
WANG Yong-xin, CHEN Zheng, LIU Bing, 
MA Liang, TANG Li-ying, ZHAO Yu-hong

School of Materials Science and Engineering,
Northwestern Polytechnical University, Xi′an 710072, China

Abstract: An atomic-scale computer simulation program of δ′(Al3Li) based on the microscopic diffusion equation and non-equilibrium free energy was firstly worked out, which can be applied to process the problem relating with time. The precipitation mechanism of δ′ was investigated by simulating the atomic pictures and calculating the order parameters, etc, and the variation in precipitation mechanism with the nearest interchange interaction energy(W1), particularly the precipitation behavior of 12%Li in Al-Li alloys was interpreted. It is found that the precipitation incubation period of δ′ is shortened, the nucleation rate is increased, and the rate of ordering process and atom clustering are increased while the nearest interchange interaction energy increases. Within the studied time period, the maximum values of long range ordering parameter and composition deviation parameter increase with the nearest interchange interaction energy increasing. The precipitation of δ′ occurs either by a congruent ordering process followed by, or by a non-classical nucleation mechanism. With increasing W1, the precipitation of δ′ leans to decomposition.

 

Key words: interchange interaction energy; precipitation; computed microstructure; order parameters; computer simulation

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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