Effects of Heterogeneity, Anisotropy and Length Scale Effects in Microscale Deformation Processes

所提出的研究的目标是系统地和单独地研究在微尺度制造中遇到的微尺度材料变形过程中的各向异性，异质性和长度尺度效应的影响。虽然本研究中采用的技术可以应用于任何微尺度制造工艺，但PI将专注于微激光喷丸成形（mLPF）。该方法是实验表征材料进行mLSP和mLPF过程通过测量诱导的残余应力与微尺度X射线衍射技术，通过测量的分布和程度的塑性变形与电子背散射衍射（EBSD），并测量最终形状的变形试样使用各种商业技术。为了隔离各向异性的影响，将在单晶上进行工艺。为了隔离异质性的影响，该过程将在双晶体的晶界附近进行。潜在的长度尺度效应的塑性变形将探测与电子背散射衍射（EBSD），它允许几何必要的位错密度的估计。这两个过程将使用有限元技术进行数值模拟，考虑到速率效应、硬化效应、材料的各向异性和非均匀性，如果实验结果认为有必要，还将考虑长度尺度效应。预期结果将有助于微制造工艺制造更高质量的微部件。对工艺能力和局限性的理解的显著提高将为新的微型零件设计提供机会。人才培养和成果传播将提高国家在微型制造业的竞争力。将作出重大努力，让传统上代表性不足的背景的学生参与研究。

The objectives of the proposed research are to systematically and individually study the effects of anisotropy, heterogeneity and length scale effects in microscale material deformation processes which are encountered in microscale manufacturing. While the techniques to be employed in this research could be applied to any microscale manufacturing process, the PIs will focus efforts Micro Laser Peen Forming (mLPF). The approach is to experimentally characterize materials subjected to mLSP and mLPF processes by measuring the induced residual stresses with microscale x-ray diffraction techniques, by measuring the distributions and degrees of plastic deformation with Electron Backscatter Diffraction (EBSD), and also to measure the final shape of the deformed specimens using various commercial techniques. In order to isolate the effects of anisotropy the processes will be performed on single crystals. To isolate the effects of heterogeneity, the processes will be performed near the grain boundary of a bicrystal. Potential length scale effects of the plastic deformation will be probed with electron backscatter diffraction (EBSD) which allows estimates of the density of geometrically necessary dislocations. The two processes will be numerically simulated using the finite element technique, taking into account rate effects, hardening effects, the anisotropic, heterogeneous nature of the material, and will incorporate length scale effects if deemed necessary by the experimental results.Expected results will help micro manufacturing processes to make higher quality micro components. The significantly improved understanding of process capability and limitations will open up opportunities for new micro part designs. Personnel development and dissemination of results will improve national competitiveness in micro manufacturing. A significant effort will be made to involve students from traditionally underrepresented backgrounds in the research.