Acquisition of a Nanoindenter

9803045 Lavernia该奖项提供了一个nanoindenter的收购支持，以服务于几个正在进行的研究需求，以及未来的研究计划处理纳米晶材料的合成-结构-性能研究在欧文的加州大学。 纳米晶体材料为材料科学家/工程师提供了独特的机会，以实现平衡材料无法实现的特性组合。 例如，据报道纳米相陶瓷表现出异常高的延展性，而纳米相金属表现出超高的硬度值。 为此，本文提出的研究计划的目的是研究纳米晶材料的机械性能的各个方面，包括在欧文的加州大学生产的粉末，涂层和散装样品。 更具体地说，该研究计划将调查：1）球磨过程中不同金属、陶瓷和金属陶瓷的显微硬度随晶粒尺寸的变化规律; 2）热喷涂纳米晶涂层中显微硬度深度分布随晶粒尺寸、孔隙率和第二相弥散相的变化规律的实验研究（取决于冷却速率和涂层厚度），3）杨氏模量行为（取决于各种纳米晶材料的晶粒尺寸和孔隙率），特别是以小尺寸存在的那些，4）具有低孔隙率的纳米晶涂层的耐磨性，5）纳米晶涂层的时间相关性质（应变率敏感性、蠕变和应力松弛），以及6）纳米晶涂层的屈服强度。 为了实现这些目标，提出了以下方法。 首先，机械合金化将用于合成纳米晶粉末的Al基合金，Inconel 718，Ni和WC/Co，强调控制污染，粒度分布和颗粒形态。 其次，机械合金化纳米晶粉末将使用两种不同的方法进行固结：热压、热等静压或热挤压和高速氧燃料（HVOF）热喷涂以制备纳米晶块状样品或涂层。 第三，将详细研究球磨、固结和HVOF热喷涂纳米晶粉末的物理和机械性能，特别关注通过高速氧燃料喷涂制备的各种纳米晶涂层。 此外，Hall-Petch强化机制在固结纳米晶材料将进行研究。 %该仪器将由加州大学欧文分校的学生和教职员工共享。 希望这项研究将影响纳米晶体材料的生长，以创建粒度小于100纳米的块状3D样品，这将大大提高所有显示这种行为的材料的性能。 这将影响材料的强度，耐腐蚀性，并提高机械性能。 ***

9803045 Lavernia This award provides support for the acquisition of a nanoindenter to serve the research needs of several ongoing, as well as future research programs dealing with the synthesis-structure-property studies of nanocrystalline materials at the University of California at Irvine. Nanocrystalline materials provide the material scientist/engineer with the unique opportunity to achieve combinations of properties that are otherwise unachievable with equilibrium materials. For example, nanophase ceramics are reported to exhibit unusually high ductilities, whereas nanophase metals are noted to exhibit ultra-high hardness values. To that effect, the objective of the research program proposed herein is to investigate the various aspects of mechanical properties of nanocrystalline materials, including powders, coatings and bulk samples produced at the University of California at Irvine. More specifically, the research program will investigate: 1) the evolution of microhardness of various metals, ceramics and cermets as a function of grain size during ball milling, 2) experimental study of the microhardness depth distribution in thermal sprayed nanocrystalline coatings as a function of grain size, porosity and second phase dispersoids (dependent on cooling rate and the coating thickness), 3) Young's modulus behavior (depending on grain size and porosity of various nanocrystalline materials), in particular those present in small dimensions, 4) wear resistance of nanocrystalline coatings with low porosity, 5) time dependent properties (strain rate sensitivity, creep and stress relaxation) of nanocrystalline coatings, and 6) yield strength of nanocrystalline coatings. To accomplish these objectives the following approach is proposed. First, mechanical alloying will be used to synthesize nanocrystalline powders of Al based alloys, Inconel 718, Ni and WC/Co, emphasizing the control of contamination, particle size distribution and particle morphology. Second , the mechanically alloyed nanocrystalline powders will be consolidated using two different approaches: hot pressing, hot isostatic pressing or hot extrusion and high velocity oxygen-fuel (HVOF) thermal spraying to prepare nanocrystalline bulk samples or coatings. Third, the physical and mechanical properties of the as-milled, consolidated and HVOF thermal sprayed nanocrystalline powders will be studied in detail, paying particular attention to various nanocrystalline coatings prepared by high velocity oxygen-fuel spraying. Moreover, Hall-Petch strengthening mechanisms in the consolidated nanocrystalline materials will be studied. %%% This instrument will be shared by students and faculty across the campus at the University of California at Irvine. It is hoped that this research will impact the growth of nanocrytalline materials to create bulk 3-D samples having grain sizes less than 100 nanometers, which would dramatically increase the performance of all materials that display this behavior. This would impact strength of materials, corrosion resistance, and improve mechanical performance. ***