Hydrogen-microstructure interactions in iron-based alloys at small scales: from amorphous, via nanocrystals, to polycrystals

小尺度铁基合金中氢与微观结构的相互作用：从非晶态、纳米晶到多晶

• 批准号: 318876084
• 负责人: Dr. María Jazmín Duarte Correa
• 金额: --
• 依托单位: Abteilung Struktur und Nano-/ Mikromechanik von Materialien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/318876084?language=en
• 关键词: Hydrogen; microstructure; interactions; iron; based

Hydrogen embrittlement (HE), which is of prime concern in steels, causes material failure and thus huge economic losses. In the past, several studies focused on HE in steels, much less in amorphous alloys, and few are found for nanocrystalline materials. Despite the multiple studies on crystalline alloys, there is still a lack of fundamental understanding and exists controversy regarding the specific effects of H and the mechanisms leading to failure of the material. This project will provide knowledge on the H effects on the mechanical behavior at small length scales in Fe-based alloys with different atomic ordering. The interplay of mechanical, chemical and electrochemical properties will be studied by in-situ nanoindentation during electrochemical charging of H. The samples will consist of single phase Fe alloys with Cr contents close to that of stainless steel: amorphous Fe50Cr15Mo15C14B6, nanocrystalline and polycrystalline ferritic Fe-Cr alloys. Of special interest are the distinct deformation mechanisms: shear bands in amorphous alloys and dislocation plasticity in crystalline ones, and their respective response due to H absorption. Nanocrystalline alloys will be studied to elucidate the interplay of shear band and dislocation dominated regimes during HE. We will identify the onset of plasticity, hardness and elastic modulus of charged and uncharged samples as indicators for embrittlement. Mechanical testing at grain boundaries in crystalline alloys will evidence the H effects and possible decohesion in regions of stress concentration. Specific data on the microstructural changes will be obtained by high resolution techniques, such as transmission electron microscopy, atomic force microscopy and electron channeling contrast imaging. H concentration and permeation will be quantified by thermal desorption spectroscopy and scanning Kelvin probe measurements to correlate the mechanical and microstructural data with the H amount and location within the structure.The fundamental insights on the HE phenomena and the effects of H absorption on the mechanical response of Fe alloys, shifting from dislocation plasticity to shear banding, will be of valuable interest for the future improvement of the materials long-term stability.

氢脆是钢中最受关注的问题，它会导致材料失效，从而造成巨大的经济损失。过去，一些研究主要集中在钢中的HE，而非晶合金中的HE较少，而纳米晶材料中的HE研究则很少。尽管对结晶合金进行了大量的研究，但对于H的具体作用和导致材料失效的机制仍然缺乏基本的认识和存在争议。本项目将提供关于H对不同原子有序铁基合金小长度尺度力学行为的影响的知识。通过原位纳米压痕技术研究h在电化学充电过程中力学、化学和电化学性能的相互作用。样品由Cr含量接近不锈钢的单相Fe合金、非晶Fe50Cr15Mo15C14B6、纳米晶和多晶铁素体Fe-Cr合金组成。特别令人感兴趣的是不同的变形机制：非晶合金中的剪切带和结晶合金中的位错塑性，以及它们各自由于H吸收而产生的响应。研究纳米晶合金以阐明剪切带和位错主导机制在HE过程中的相互作用。我们将确定带电和不带电样品的塑性，硬度和弹性模量的开始作为脆化的指标。在晶界处的力学测试将证明H效应和应力集中区域可能的解聚。显微结构变化的具体数据将通过高分辨率技术获得，如透射电子显微镜、原子力显微镜和电子通道对比成像。H浓度和渗透率将通过热解吸光谱和扫描开尔文探针测量来量化，以将机械和微观结构数据与H的数量和结构内的位置联系起来。关于HE现象的基本见解以及H吸收对铁合金力学响应的影响，从位错塑性转向剪切带，将对未来提高材料的长期稳定性具有重要意义。