Acquisition of a Nano-Indenter for Moderately Elevated Temperatures

该奖项为购买纳米压痕系统提供支持，该系统具有在环境室中的新功能，允许在-50℃至100℃对技术上重要的材料进行测试。该仪器允许进行各种各样的测试，包括亚微米尺寸的硬度测试，微划痕测试，通过循环压痕和恒载荷蠕变测试期间的力位移测量来确定阻尼特性。该仪器将被材料科学研究所的成员在几个材料项目中大量使用：(i)测量常规和纳米晶热障涂层和纳米晶耐磨材料的单个层的性能，为建模和理解涂层的性能-微观结构-加工关系提供机械性能；（ii）由于铝消耗导致相和化学计量变化而导致的高度局部的性能变化的映射；（iii）在略微升高的温度下测量薄聚合物的性能，（iv）在环境温度和适度升高的温度下测量电子器件中的薄膜性能，(v)表征经历层间相互扩散的系统中的机械性能变化。最后，该仪器将用于推进在纳米压痕的非常精细尺度上的实验中揭示的性质的理解。研究表明，变形特性（以及由此推断的力学性能）受到长度尺度的影响，而长度尺度被认为是由微观结构的特征决定的。通过压痕试验确定的力学性能的解释不能与长度尺度依赖行为的基本问题分开。这项工作将扩展当前尺寸相关压痕的研究，并与加工、金相学和电子显微镜方面的专家就样品制备和表征进行合作。此外，关于如何从压痕试验中开发非弹性材料特性，特别是那些与时间和温度相关的材料特性，仍然存在悬而未决的问题。这些问题将在正在进行的和未来的研究项目中详细讨论。% % % * * *

9802716 Begley This award provides support to purchase a nano-indentation system which has the new feature of being in an environment chamber allowing tests to be made from -50 C to 100 C on technologically important materials. This instrument allows a wide variety of tests, including submicron-sized hardness tests, micro-scratch tests, the determination of damping properties via force-displacement measurements during cyclic indentation and constant load creep tests. The instrument will be heavily used by Institute of Materials Science members in several materials projects: (i) the measurement of individual layer properties in conventional and nanocrystalline thermal barrier coatings and nanocrystalline wear resistant materials, to provide both mechanical properties for modeling and the understanding of properties-microstructure-processing relationships coatings, (ii) the mapping of highly localized property changes due to aluminum depletion which leads to phase and stochiometry changes, (iii) the measurement of thin polymer properties at slightly elevated temperatures, (iv) the measurement of thin film properties in electronic devices at ambient and moderately elevated temperatures, (v) characterizing of mechanical property variations in systems experiencing interdiffusion between layers. Finally, the instrument will be used for advancing the understanding of properties revealed in experiments on the very fine scale of nano-indentation. It has been shown that the deformation characteristics (and hence, inferred mechanical properties) are influenced by length scales presumed to be governed by the characteristics of the microstructure. The interpretation of mechanical properties determined via indentation tests can not be separated from the fundamental problem of length-scale-dependent behavior. This work will extend current research in size-dependent indentation and collaborate with experts in processing, metallography and electron microscopy regarding sample preparation and characterization. Additionally, open issues remain on how to develop inelastic material properties from indentation tests, particularly those that are time-and temperature-dependent. These issues will be addressed in detail in on-going and future research programs. %%% ***