基于孪生随机形核的镁合金细观塑性本构与损伤行为研究

项目名称： 基于孪生随机形核的镁合金细观塑性本构与损伤行为研究

项目编号： No.11462002

项目类型： 地区科学基金项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 蓝永庭

作者单位： 广西科技大学

项目金额： 52万元

中文摘要： 本项目针对镁合金在室温变形条件下独立滑移系不足，出现大量孪生变形，导致室温塑性低及变形加工困难的问题，着重研究孪生变形机制及其对镁合金多晶材料微结构非均匀演化的影响，考虑孪生形核与长大的随机性、非均匀性的特点，采用随机理论或WEIBULL理论描述与孪生形核相联系的孪生位错类型分布与演化，结合晶体塑性理论尝试发展一种细观塑性本构关系的新的方程描述，采用多晶集合体开展数值模拟研究。主要研究：（1）针对各种应变量的镁合金样品中孪晶的种类、形貌以及与基体之间的晶体学关系开展试验研究。（2）采用随机理论或WEIBULL理论对孪晶形核机制进行描述，并结合晶体塑性理论发展新的孪生变形模型，在此基础上，建立晶体细观本构方程的新的力学描述。（3）采用新的本构方程描述，建立多晶集合体代表性单元研究在各种路径加载情形下孪晶形核与长大规律，以及对微结构不均匀演化的影响，探明循环应变下孪晶界损伤机制。

中文关键词： 镁合金；孪生随机形核；本构关系；跨尺度；损伤

英文摘要： This project mainly focuses on the twinning mechanism and the micro-structural heterogeneous evolution of Mg alloy polycrystalline material due to short of independent slip system and occurring a large number of twin deformation, which results in poor plasticity and hard deformation at room temperature. In consideration of the randomness and heterogeneity of twinning nucleation and growth, the distribution and evolution of twin dislocation type relating to twinning nucleation are represented adopting the random theory or WEIBULL theory. The new description of Meso-plastic constitutive relation is attempted to develop based on the crystalline plasticity theory and the numerical simulation study is developed with polycrystalline aggregate. The main researches are that (1) An experimental study is carried out on the twin variety and morphology and crystallographic orientation with the matrix of Mg alloy samples at the different strain. (2) The mechanism of twinning nucleation is described with the random theory or WEIBULL theory and the new twinning deformation model is developed using the crystalline plasticity theory. On this basis, the new description of crystal meso-constitutive equation is established. (3) The law of twinning nucleation and growth is investigated by establishing representative volume element of polycrystalline aggregate with the new description of crystal meso constitutive equation at all kinds of loading path so as to further revealing the micro-structural heterogeneous evolution and ascertaining the damage mechanism of twin boundaries.

英文关键词： Mg alloy;twinning random nucleation;constitutive relation;trans-scale;damage