Mg-1.7Gd-0.9Y(at.%)合金时效初期结构及析出相微观结构演变的原子多尺度模拟

项目名称： Mg-1.7Gd-0.9Y(at.%)合金时效初期结构及析出相微观结构演变的原子多尺度模拟

项目编号： No.51201063

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 金属材料学科

项目作者： 吴玉蓉

作者单位： 湖南科技大学

项目金额： 25万元

中文摘要： 时效强化是Mg-Gd-Y系合金强化的重要手段之一，时效初期阶段微观结构的多样性及演变的快速性，很难采用实验手段来研究；而对时效后期过程中实验上由于无法动态跟踪析出相微观结构演变，故有关微观结构演变机理有分岐。本项目选取该合金系某典型含量Mg-1.7Gd-0.9Y(at.%) 合金作为研究对象，利用探索微观结构演变的有效原子模拟技术- - 动态蒙特卡罗和分子动力学方法，且把这两种方法相结合，并结合嵌入原子模型首次系统模拟合金在25-350℃的时效行为、微观结构演变规律及机理，分析时效初期微观结构特征，并提出相应模型，探索时效初期行为对后期析出相的影响；确定沉淀析出序列、析出相结构、成分和体积分数；观察时效过程中析出相微观结构演变规律；探究析出相微观结构演变机理，并用分子动力学方法研究不同时效阶段中各微观结构下合金的力学性能，确定最佳时效温度范围，为新型镁稀土合金的时效工艺提供指导。

中文关键词： 第一性原理；分子动力学；时效初期；纳米丝；扩散机制

英文摘要： Ageing is an effective way for improving strength of Mg-Gd-Y alloys. During the early ageing process, the microstructure of the alloys possesses variety and changes very fastly, resulting to study difficultly them on experimental side. Because the evolution of the microstructure of precipitated phases is unable to track dynamically by experiment during the lately ageing process, there are several bifurcation theories on the evolution mechanism of the precipitated phase microstructure. In the present project, based on a typical content Mg-1.7Gd-0.9Y (at.%) alloy of the Mg-Gd-Y alloys, the ageing behavior,microstructure evolution discipline and mechanism for the alloy at 25-350℃ have been calculated firstly systematically using bedded atom model, combining Kinetic Monte Carlo with Molecular Dynamic methods simulations in a sequential, which are effective atomic simulations techniques allowing one to simulate the process of microstructure evolution. A model will be established for the microstucture during the early ageing process, to study the relationship of the microstructure in early ageing process with that of the final precipitated phase. Furthermore, we will get the precipitation sequence,microstructure,composition and volume fraction of the precipitated phase. The microstructure which evolves will be tracke

英文关键词： first-principle；Molecular Dynamics；Early aging stage；nano-wire；diffusion mechanism