Untersuchung des Wasserstoffeinflusses auf die Nukleation und Bewegung von Versetzungen mit einem elektrochemischen nanoindentierenden AFM

使用电化学纳米压痕 AFM 研究氢对位错成核和运动的影响

基本信息

批准号：
46199164
负责人：
Professor Dr. Horst Vehoff
金额：
--
依托单位：
Lehrstuhl für Experimentelle Methodik der Werkstoffwissenschaften
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2007
资助国家：
德国
起止时间：
2006-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/46199164?language=en
关键词：
Untersuchung des Wasserstoffeinflusses auf die

项目摘要

In the first phase of this project the effect of hydrogen on dislocation nucleation was studied with a NI-AFM. For this, a electrochemical three electrode setup was constructed and incorporated into the NI-AFM. The newly developed ECNI-AFM is capable of performing nanoindentation as well as imaging inside electrolytes. This setup was successfully used to study the effect of cathodically charged hydrogen on dislocation nucleation in pure metals and alloys. It was shown that hydrogen reduces the pop-in load by reducing the activation energy for dislocation nucleation. This new method was able to rank the sensitivity of materials to hydrogen embrittlement not only globally but also for the single phases and grains within a microstructure. The activation energy for dislocation nucleation is related to the shear modulus μ, dislocation core radius p and stacking fault energy, which in turn are altered by hydrogen. However, the effect of hydrogen on each of these parameters could not be measured separately. Therefore, in the planned project the same system will be converted to an electrochemical nano compression (ECNC) machine with the help of a flat punch instead of an indenter. The results of this new technique in combination with the ECNI-AFM results should provide the needed additional information to discriminate the effect of hydrogen on each of the above-mentioned parameters, μ, p, and by measuring the shear stress, strain rate sensitivity within defined slip band as well as the slip band nucleation stress in nano-pillars. Smooth specimens should mainly show the effect of surface and sub-surface enrichment on nucleation. Therefore, ECNC test on notched samples and bending tests are planned in order to study the effect of local hydrogen enrichment on notches. The advantage of this technique is, that the globally measured data, as yield stress and stress-strain curves can be directly correlated to local events.

在该项目的第一阶段，使用 NI-AFM 研究了氢对位错成核的影响，为此，构建了电化学三电极装置并将其纳入新开发的 ECNI-AFM 中。该装置成功地用于研究阴极充电氢对纯金属和合金中位错成核的影响。通过降低位错成核的活化能，这种新方法不仅能够对材料对氢脆的敏感性进行排序，而且还能对微观结构内的单相和晶粒的敏感性进行排序。位错成核的活化能与剪切模量相关。 μ、位错核半径 p 和堆垛层错能，而氢又会改变这些参数。然而，氢对这些参数的影响无法单独测量，因此，在计划的项目中，同一系统将被转换为。这种新技术的结果与 ECNI-AFM 结果相结合，可以提供所需的附加信息，以区分氢对每种材料的影响。上述参数μ、p，并通过测量滑移带内定义的剪切应力、应变率敏感性以及纳米柱中的滑移带形核应力，应主要显示表面和次表面的影响。因此，计划对缺口样品进行 ECNC 测试和弯曲测试，以研究局部氢富集对缺口的影响。该技术的优点是，可以获得全局测量数据，如屈服应力和应力-应变曲线。可以直接与当地事件相关。