Indentation creep: New machine and test methodology development at various length scales, high temperatures and low deformation rates

压痕蠕变：各种长度尺度、高温和低变形率下的新机器和测试方法开发

• 批准号: 326946902
• 负责人: Professor Dr.-Ing. Karsten Durst
• 金额: --
• 依托单位: Fachgebiet Physikalische Metallkunde
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/326946902?language=en
• 关键词: Indentation; creep; New; machine; test

In the first funding period, a new high temperature and high load nanoindenter, which is operated inside a scanning electron microscope (SEM) under vacuum condition has been developed and successfully installed at TU Darmstadt. The operational temperature of the new system ranges from RT up to 1100°C and dynamic indentation experiments with max. loads of up to 1 N are possible. During the first period, the system was successfully applied to glass, Mo and Ni and material properties like modulus of elasticity, hardness as well as rate sensitivity and activation volume have been successfully determined in the whole temperature range. Furthermore, new test protocols, like the constant contact pressure method have been developed for determination of creep properties and the brittle to ductile transition has been successfully analyzed using dynamic indentation testing. High temperature nanoindentation experiments on alloys for high temperature application remains however challenging, mainly due to the high hardness of the alloys at elevated temperature and the strong chemical interaction of the tip material with the samples. This leads to very high tip wear and potentially unreliable data acquisition. Nevertheless, we were able to show that by applying test procedures using large indentations depths and/or short contact times, with a new step load creep method, even critical materials such as Ni can be successfully tested at ultra-high temperatures. During the second funding period it is planned to address the issues mentioned above by developing a user toolbox for testing relevant high temperature materials like Ni-based alloys at or close to their application temperature. This toolbox will be designed as an application guide to select the appropriate test procedure, tip geometry as well as a suitable combination of sample and tip material for the respective purpose.The focus here will be on the development of new loading protocols for non-pyramidal indenter geometries for characterizing material parameters on different length and time scales, in particular, for testing relevant Ni-based HT alloys. Therefore, different type of indentation experiments will be performed on reference materials (Ni-solid solutions, NiAl, IN718, ERBO1A) with well-known mechanical properties at elevated temperatures, whereas the data evaluation of new tip geometries will be supported by Finite Element modelling. Furthermore, new and more stable tip materials will be sought and tested within the project. Therefore, a diffusion couple approach is used to analyze the chemical interaction between critical sample and potential new tip materials. Chemically inert materials are then used as new tip materials, studying their performance during indentation testing at elevated temperature.

在第一个融资期间，已经开发并在TU Darmstadt上成功安装了在真空条件下在扫描电子显微镜（SEM）内进行扫描电子显微镜（SEM）内操作的新的高载荷纳米INDENTER。新系统的运行温度范围从RT到1100°C，并具有最大的动态压痕实验。最多可承受1 N的负载。在第一个时期，该系统已成功地应用于玻璃，MO和NI以及材料特性，例如弹性，硬度以及速率敏感性和激活量的模量，已在整个温度范围内成功确定。此外，已经开发了新的测试方案，例如用于确定蠕变特性的恒定接触压力法，并且使用动态压痕测试成功地分析了易碎到延性的延性过渡。然而，高温纳米构造实验的高温施用仍然挑战，这主要是由于合金在升高温度下的高硬度以及尖端材料与样品的较强化学相互作用。这会导致很高的尖端磨损和潜在不可靠的数据获取。然而，我们能够证明，通过使用较大的压痕深度和/或短接触时间应用测试程序，使用新的步骤载荷方法，即使是关键材料（例如NI）也可以在超高温度下成功测试。在第二个融资期间，计划通过开发一个用户工具箱来解决上述问题，用于测试相关的高温材料，例如在其应用温度下或接近其应用温度。该工具箱将被设计为申请指南，以选择适当的测试程序，尖端几何形状以及用于相关目的的样品和尖端材料的合适组合。此处的重点是开发针对非锥体凹痕几何的新加载协议，用于在不同的长度和时间范围内表征材料参数，尤其是测试相关的HT ni ni ni ni ni syloys。因此，将在参考材料（Ni-Solid溶液，NIAL，IN718，ERBO1A）上进行不同类型的压痕实验，在升高温度下具有众所周知的机械性能，而新尖端几何的数据评估将由有限元建模支持。此外，将在项目中感知和测试新的，更稳定的小费材料。因此，使用扩散夫妇方法来分析关键样品和潜在的新尖端材料之间的化学相互作用。然后将惰性材料用作新的尖端材料，在升高温度下研究其凹痕测试期间的性能。