高应变率下纯铜织构与绝热剪切敏感性的相关性研究

项目名称： 高应变率下纯铜织构与绝热剪切敏感性的相关性研究

项目编号： No.50871125

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 陈志永

作者单位： 中南大学

项目金额： 28万元

中文摘要： 采用理论推导、计算机模拟以及实验验证相结合的综合分析方法，系统研究了高应变率下FCC金属纯铜织构与变形行为特征之间的关系。通过适当的形变与热处理，获得了具有不同原始组织和初始织构的多晶纯铜样品；制备了不同取向铜单晶。运用Instron电子拉伸机和分离式霍普金生压杆（SHPB）等实验装置，研究了准静态、动态压缩和强迫剪切条件下织构多晶铜和不同取向单晶铜的力学行为以及变形特征。基于微观晶体塑性细观力学和不同类型多晶体塑性变形模型，考虑晶体学取向分布即织构的影响及不同加载条件下可能的微观塑性变形机制，研究了纯铜织构对其动态力学性能的影响规律以及导致其各向异性的微观机理。结合OM、SEM-EBSD、TEM以及ODF等微观组织和织构测试、分析及表征技术，系统研究了相应条件下微观组织以及晶体取向变化规律；提出一个改进的亚晶旋转动态再结晶模型，阐明了剪切带内超细晶的形成机制，证实了带内发生再结晶的动力学可行性；研究了织构和绝热剪切敏感性相互间的关系，定性解释了绝热剪切敏感性的各向异性。研究内容丰富了高应变率下金属动态力学性能与绝热剪切敏感性方面的研究内容，同时可为高性能材料优选、设计和制备提供依据。

中文关键词： 织构；绝热剪切敏感性；各向异性；动态力学性能；高应变率。

英文摘要： The relationship between textures and deformation behaviors of pure copper with face-centered-cubic crystal structure at high strain rates were investigated systematically by theoretical analysis, computer simulation and experimental verification. The polycrystalline samples with different initial microstructures and textures were obtained by proper deformation and heat-treatment while some single-crystal coppers with different orientaions were prepared. The quasi-static, dynamic compressive and forced shear mechanical behaviors and deformation characteristics were studied by means of Instron apparatus and Split-Hopkinson pressure bar technology. Taking into account of the crystal orientation distribution and possible plastic deforamtion mechanism,the effects of textures for pure copper on the mechanical properties and the corresponding mechanism resulting in the anisotropy were analysed on the basis of the microscopic crystal plasticity of theory and different type models of plastic deformation of polycrystalline aggregates. The microstructural and crystal orientation evolution were examined by different ways including optical microscopy(OM),electron back scattering diffraction (EBSD),transmission electron microscopy (TEM) and orientation distribution functions (ODFs). At the same time, the influences of textures and microstructures on the adiabatic shear susceptibility were invesigated. Based on the shear stress-shear strain curves and adiabatic shear dissipation energy, the difference of adiabatic shear suscepptility for samples with different crystal orientaions can be explained qualitaively. A rotational dynamic recrystallization model was proposed to illustrate the formation of the elonged ultrafine gains,the calculated results prove the possibility that dynamic recrystallization can happen in shear bands. The results will enrich and develop the researches on the dynamic mechanical properties and adiabatic shear susceptibility of metals and alloys at high strain rates. Meantime, it will establish a scientific foundation for the optimization, design and fabrication of materials with high performance.

英文关键词： texture;adiabatic shear susceptibility; anisotropy; dynamic mechanical properties; high strain rate