Scale-Dependent Crystal Plasticity and Nanoindentation-Induced Dislocation Microstructure

尺寸相关的晶体塑性和纳米压痕引起的位错微观结构

• 批准号: 0800168
• 负责人: Yanfei Gao
• 金额: $ 31.66万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0800168&HistoricalAwards=false
• 关键词: Scale; Dependent; Crystal; Plasticity; Nanoindentation; Scale; Dependent; Crystal; Plasticity; Nanoindentation

CMMI 0800168: Scale-Dependent Crystal Plasticity and Nanoindentation-Induced Dislocation MicrostructureYanfei Gao (PI), George M. Pharr (Co-PI)University of Tennessee, KnoxvilleThe objective of this research is directed to a mechanistic understanding of the scale-dependent plastic behavior of single crystals by a quantitative comparison of measured and simulated near-surface dislocation microstructure induced by nanoindentation. Existing theoretical/experimental comparison has generally been limited to macroscopic information such as hardness. Experimentally, nanoindentation tests will be employed to achieve controlled defect distributions by varying the material type, indenter shape, and crystallographic orientations. Artifacts in continuous stiffness measurement and reliable hardness extraction will be examined. The spatially resolved lattice-misorientation measurements with sub-micron resolution will be performed using microfocus x-ray technique. From modeling standpoint, the measured dislocation microstructure will be used as input to examine the crystallographic nature of the relationship between lattice rotation, incompatible lattice deformation, and geometrically-necessary-dislocation distributions. Thus various gradient plasticity theories can be validated and calibrated. The source limited behavior will be investigated by applying various degrees of pre-strain prior to indentation and qualitatively by utilizing a discrete dislocation model. The research will lead to benefits and impacts for mechanics theorists in the critical evaluation of scale-dependent constitutive models and for materials scientists in advancing design capabilities of small scale material structures. The multidisciplinary nature will be a disseminative example for undergraduate and graduate education. New instructional materials and hands-on laboratory demonstrations will be developed for incorporation into outreach and diversity programs, which are designed to inspire interests of high school students and to help recruit students from underrepresented groups in engineering sciences.

CMMI 0800168：依赖于尺度的晶体可塑性和纳米指标诱导的脱位微结构微观结构，gao（PI），田纳西州的乔治·M·帕尔（George M. Pharr）（CO-PI），这项研究的诺克斯维尔（Knoxvillethe）的目标是通过对量度依赖于规模依赖于量表的量子构成的量子依赖于量表的量子的机械构成量的机械构成量的机械构造的，并依赖于量表依赖于尺度的形式的量子，并依赖于量表依赖于尺度的塑性，并依赖于量表依赖于规模的塑性。纳米互动。现有的理论/实验比较通常仅限于宏观信息，例如硬度。在实验上，将通过改变材料类型，凹痕形状和晶体学取向来实现纳米凹痕测试来实现受控的缺陷分布。将检查连续刚度测量和可靠硬度提取的伪影。将使用Microtocus X射线技术进行以下微米分辨率的空间分辨的晶格 - 相位测量。从建模的角度来看，测得的错位微结构将用作输入，以检查晶格旋转，不兼容的晶格变形和几何含量的脱位分布之间关系的晶体学性质。因此，可以验证和校准各种梯度可塑性理论。源有限的行为将通过在压痕前应用各种程度的预算来研究，并通过使用离散的脱位模型进行定性。这项研究将在依赖规模依赖性本构模型的批判性评估和材料科学家在提高小规模材料结构的设计能力方面对力学理论家的好处和影响。多学科的本质将是本科和研究生教育的传播典范。将开发新的教学材料和动手实验室示范，以纳入外展和多样性计划，这些计划旨在激发高中生的利益，并帮助招募工程科学中代表性不足的学生的学生。