CAREER: Surface Texturing of Bulk Metallic Glasses for Fabrication of Complex Micro Optics

这个教师早期职业发展（CAREER）补助金将提供一种新技术的基本理解，通过在大块金属玻璃上生成表面纹理来制造复杂的微光学器件。具有表面纹理的微光学器件在广泛的应用中发挥着重要作用，例如汽车照明系统，高分辨率显示面板，激光系统的衍射光栅和交通安全的反射镜。块体金属玻璃由于具有高硬度、高耐蚀性和无表面缺陷等优点，在微光学器件制造中得到越来越多的应用。然而，由于材料的热变形，使用块体金属玻璃用现有技术生产的微光学器件通常具有高的制造成本、有限的几何精度和表面质量。该学院早期职业发展（CAREER）奖支持一种新技术的基础研究，通过金刚石加工与应用振动在大块金属玻璃上产生表面纹理来制造复杂的微光学器件。新技术将显著降低生产成本，提高零件质量（几何精度和表面粗糙度）。该奖项还支持将研究成果融入教育，让公众了解精密制造和光学工程，培养先进制造领域的下一代工程师。在新技术中，工件的平面振动会导致刀具与工件的间歇接触，从而导致材料去除区域的温度和应力发生高频变化。研究的第一个目标是揭示大块金属玻璃的非晶-晶转变与温度变化之间的关系。这将通过织构化过程的有限元建模来预测温度和非晶-结晶转变来实现。模拟结果将通过测量时空温度使用一个新的系统相结合的高温计和红外相机，并通过X射线衍射表征结晶的原始非晶微观结构进行验证。第二个目标是确定织构化过程中应力变化对块体金属玻璃变形模式（非均匀和均匀）的影响。为了实现这一目标，将通过有限元方法模拟应力变化，并利用声发射信号原位测量材料变形模式。第三个目标是确定工艺参数（工具几何形状，纹理化条件和振动辅助参数）对表面纹理几何精度的影响。包括强迫振动的工具和辅助振动的工件的过程动力学将解析建模，和模拟的纹理几何形状将使用表面轮廓仪进行实验验证。将在各种工艺参数下对这三个目标进行建模和实验。

This Faculty Early Career Development (CAREER) grant will provide fundamental understanding of a novel technique to fabricate complex micro optics through generating surface textures on bulk metallic glasses. Micro optics with surface textures play a significant role in broad applications, such as automotive illumination systems, high-resolution display panels, diffraction gratings for laser systems, and reflective mirrors for traffic safety. Bulk metallic glasses have been increasingly used in fabricating micro optics due to high hardness, high corrosion resistance and no surface defects. However, micro optics produced with existing techniques using bulk metallic glasses usually have high fabrication cost, limited geometric accuracy and surface quality due to thermal deformations of the material. This Faculty Early Career Development (CAREER) award supports fundamental research of a novel technique to fabricate complex micro optics through generating surface textures on bulk metallic glasses by diamond machining with applied vibrations. The new technique will significantly reduce production cost, and improve component quality (both geometric accuracy and surface roughness). The award also supports activities to integrate research results into education, expose the public to precision manufacturing and optics engineering, and prepare next-generation engineers in advanced manufacturing areas.In the new technique, the planar vibration of the workpiece causes intermittent tool-workpiece contact, resulting in high-frequency variations of temperature and stress in material removal region. The first research objective is to uncover the relationship between amorphous-crystalline transition of bulk metallic glasses and temperature variation. It will be achieved by finite element modeling of the texturing process to predict temperature and amorphous-crystalline transition. The simulation results will be verified by measuring spatial-temporal temperature using a novel system combining a pyrometer and an infrared camera, and characterizing crystallization of the original amorphous microstructure through X-ray diffraction. The second objective is to determine the influences of stress variation in texturing process on deformation mode (inhomogeneous and homogeneous) of bulk metallic glasses. To achieve this objective, stress variation will be simulated through finite element method, and material deformation mode will be measured in-situ using acoustic emission signals. The third objective is to determine the effects of process parameters (tool geometry, texturing conditions, and vibration assistance parameters) on geometric accuracy of surface textures. The process dynamics including forced vibrations of tool and assisted vibrations of workpiece will be analytically modeled, and the simulated texture geometry will be experimentally verified using surface profilometer. Modeling and experiments for the three objectives will be conducted under various process parameters.