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Analysis of thermal desorption of hydrogen in metallic alloys
Acta Materialia ( IF 9.4 ) Pub Date : 2018-02-01 , DOI: 10.1016/j.actamat.2017.11.011
A. Raina , V.S. Deshpande , N.A. Fleck

Abstract The degree of embrittlement of metallic alloys is sensitive to the concentration of absorbed hydrogen, with hydrogen traps (particularly at grain boundaries) playing an important role. Thermal desorption spectrometry (TDS) is widely used to measure the detrapping and diffusion behaviour of hydrogen in metallic alloys. However, it is problematic to obtain a consistent interpretation of TDS data from the literature, due to the large number of material parameters that influence the measurement, and this results in a wide range of quoted values for trapping parameters such as the number of trap types, trap binding energies and trap densities. In this paper, the governing partial differential equation for hydrogen diffusion with sink and source terms for a single trap is formulated in non-dimensional form, assuming local equilibrium between the hydrogen atoms at the lattice sites and the trap sites. An asymptotic analysis reveals two distinct regimes of diffusion behaviour in TDS tests. Kissinger-type behaviour is expected in a TDS test for low heating rates on an alloy with a low lattice activation energy. Contour maps of maximum hydrogen flux and the corresponding temperature are plotted using axes of trap density and trap binding energy by making use of the full numerical solution (and asymptotic solutions). These maps serve as a useful tool for an accurate and simple determination of the trap binding energy as well as the trap density.

中文翻译:

金属合金中氢的热脱附分析

摘要 金属合金的脆化程度对吸氢浓度很敏感,其中氢陷阱(特别是在晶界处)起着重要作用。热解吸光谱 (TDS) 被广泛用于测量金属合金中氢的脱附和扩散行为。然而,由于影响测量的大量材料参数,从文献中获得对 TDS 数据的一致解释是有问题的,这导致捕获参数的引用值范围很广,例如捕获类型的数量,陷阱结合能和陷阱密度。在本文中,以无量纲形式制定了具有单个陷阱的汇和源项的氢扩散的控制偏微分方程,假设晶格位置和陷阱位置的氢原子之间存在局部平衡。渐近分析揭示了 TDS 测试中两种不同的扩散行为。在对具有低晶格活化能的合金进行低加热速率的 TDS 测试中,预计会出现 Kissinger 型行为。通过利用完整的数值解(和渐近解),使用陷阱密度和陷阱结合能的轴绘制最大氢通量和相应温度的等值线图。这些图可作为一种有用的工具,用于准确和简单地确定陷阱结合能以及陷阱密度。在对具有低晶格活化能的合金进行低加热速率的 TDS 测试中,预计会出现 Kissinger 型行为。通过利用完整的数值解(和渐近解),使用陷阱密度和陷阱结合能的轴绘制最大氢通量和相应温度的等值线图。这些图可作为一种有用的工具,用于准确和简单地确定陷阱结合能以及陷阱密度。在对具有低晶格活化能的合金进行低加热速率的 TDS 测试中,预计会出现 Kissinger 型行为。通过利用完整的数值解(和渐近解),使用陷阱密度和陷阱结合能的轴绘制最大氢通量和相应温度的等值线图。这些图可作为一种有用的工具,用于准确和简单地确定陷阱结合能以及陷阱密度。
更新日期:2018-02-01
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