Collaborative Research: Evolution of Strain and Microstructures in the Presence of Solute Hydrogen - a Mulitscale Experimental Investigation

氢脆是金属结构的突然和灾难性失效，造成的损失相当于国内生产总值的3%。这种增强的失效机制对从化石燃料驱动的运输系统过渡到氢动力运输系统提出了重大挑战。要做到这一点，就必须发现氢增强失效的机制。这一进展将使在氢环境中使用的合金的设计以及预测组件寿命的模型的开发成为可能。威斯康星大学麦迪逊分校和康奈尔大学之间的这项实验性合作努力旨在确定驱动氢增强失效的基本机制。通过与日本九州大学（Kyushu University）及其国际碳中和能源研究所（international Institute for Carbon Neutral Energy Research）的教员合作，在这方面接受教育的学生将获得国际经验。此外，pi将开发和分发基于工程的课堂活动，强调金属系统的机械性能。氢环境对金属结构力学性能的有害影响是有口可查的，但驱动强化突然失效的基本机制仍然难以捉摸。这项合作将采用一种多尺度实验方法，旨在验证溶质氢可以加速微观结构（应变）的演变，并且伴随着高氢浓度，建立了决定断裂路径和机制的局部条件。利用高能x射线衍射和原位机械加载技术，在康奈尔高能同步加速器源（CHESS）上动态探索氢对微尺度晶格应变和取向演化的影响。这项工作将与在不同条件下加载不同程度应变的材料的TEM中加载后的微观结构表征相结合，包括在原位测试中使用的材料。该前提的确认将为设计耐氢微结构以及基于物理的预测模型提供基础。

Hydrogen embrittlement, a sudden and catastrophic failure, of metallic structures, accounts for losses equal to 3 percent of the gross domestic product. This enhanced failure mechanism presents a significant challenge to transitioning from a fossil fuel powered transportation system to one powered by hydrogen. For this to occur, the mechanisms by which hydrogen enhances the failure must be discovered. This advance will enable design of alloys for use in hydrogen environments as well as development of models to predict component lifetime. This experimental collaborative effort between UW-Madison and Cornell University seeks to identify the fundamental mechanisms driving the hydrogen-enhanced failure. Students educated in this effort will gain international experience through collaboration with faculty at Kyushu University in Japan and their International Institute for Carbon Neutral Energy Research. In addition, the PIs will develop and distribute engineering based in-class activities that emphasize mechanical properties of metallic systems.The deleterious impact of a hydrogen environment on the mechanical properties of metallic structures is well-documented and yet the fundamental mechanisms driving the enhanced sudden failure remain elusive. This collaborative effort will employ a multi-scale experimental approach designed to test the premise that solute hydrogen can accelerate the evolution of the microstructure (strain) and it, along with attendant high hydrogen concentration, establishes the local conditions that determine the fracture path and mechanism. The influence of hydrogen on the evolution of microscale lattice strains and orientations will be probed dynamically using high energy x-ray diffraction and in-situ mechanical loading at Cornell High-energy Synchrotron Source (CHESS). This effort will be coupled with post-loading microstructure characterization in the TEM of materials loaded to varying degrees of strain under different conditions, including those used in the in-situ testing. Confirmation of the premise will provide a basis for design of hydrogen tolerant microstructures as well as for physically-based predictive models.