应变率影响下的纳晶材料晶粒运动和剪切带现象研究

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吴友义

（南京工业大学 机械与动力工程学院，江苏 南京 210009）

摘要： 在相混合模型的基础上，建立了一种新的本构模型来研究应变率对纳晶材料力学行为的影响。在模型建立过程中，考虑到了晶内相和晶界相不同的变形机制：位错滑移和晶界滑移，并结合了弱化因素：晶粒旋转和晶粒迁移。为了验证理论模型的正确性，计算结果与实验结果进行了对比，发现两者吻合的很好，进一步的研究表明剪切带的半带宽与晶粒尺寸的变化都表现出明显的应变率相关性。通过应变硬化率的变化情况，得到了材料由应变硬化到应变软化的转变现象。

关键词：  纳晶材料； 位错； 晶粒旋转； 剪切带； 应变率

中图分类号： TB 3文献标志码： A

Investigation of Grain Motion and Shear Band Behavior for NanocrystallineMaterials Under the Effects of Strain Rate 

WU Youyi

 (SchoolofMechanicaland Power Engineering,NanjingTechUniversity,Nanjing210009,China)

Abstract: To evaluate the influences of strain rate on mechanical behavior of nanocrystalline (NC) materials, a new mechanical constitutive model based on phase mixture model was built. Different kinds of deformation mechanisms like dislocation gliding and grain boundary sliding were considered with the consideration of softening factors: grain rotation and grain migration. Then the calculated results were compared with corresponding experimental curves and strong, which indicated that the predictions kept in good agreement with that of experiments. Intense strain rate dependent effects were exhibited on the shear band broaden and grain size growth. Work hardening rate evolution with strain under high strain rate gives raise to the fact about deforming localization.

Key words: nanocrystalline materials; dislocation; grain rotation; shear band; strain rate

 收稿日期： 20150711

基金项目： 国家自然科学基金项目（10502025,10872087,11272143）；教育部新世纪人才项目（NCET120712）；霍英东青年教师基金项目（101005）；江苏省支撑项目（BE2009170）.

作者简介： 吴友义（1990—），男，硕士研究生.

文章编号： 16726987（2016）05055006； DOI： 10.16351/j.16726987.2016.05.015