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MM: Fachverband Metall- und Materialphysik

MM 23: Topical Session: Hydrogen in Materials: from Storage to Embrittlement III

MM 23.4: Vortrag

Dienstag, 19. März 2024, 12:45–13:00, C 130

The role of manganese and aluminium on hydrogen trapping and diffusion in Mn/Al rich steel alloys — Bikram Kumar Das¹, •Mauricio Bonilla¹, Poulami Chakraborty¹, and Elena Akhmatskaya^1,2 — ¹BCAM - Basque Center for Applied Mathematics, Bilbao, Spain — ²IKERBASQUE, Basque Foundation for Science, Bilbao, Spain

Hydrogen-induced embrittlement (HIE) remains a serious bottleneck for using steel in infrastructure for H₂ storage and transport. Small amounts of Al and Mn have been shown to mitigate HIE, but the proposed mechanisms are often contradictory. To address this problem, we present a systematic approach to model the local environments (LEs) around the H-binding sites in FCC Fe-Mn-Al alloys up to the 3^rd nearest neighbor (NN) shell. First, the most favorable LEs are determined using Density Functional Theory (DFT). Then, the local impact of Al/Mn content and distribution on the binding and diffusion of H is examined through the nudge elastic band method and crystal orbital Hamilton population analysis. We found that H-binding correlates most strongly with Al content, and is weakly influenced by Mn up to 5 wt%. Moreover, direct H-Al bonding destabilizes H binding, but the presence of Al in the 2^nd NN shell of the H-binding site leads to a strong stabilizing effect by promoting H-Fe bonding. The presence of Al and Mn in grain boundaries and precipitates is known to play a prominent role in HIE. Here, we show that Al ability to indirectly trap H in bulk austenite could mitigate HIE. The analysis approach in this work could readily be adapted to study similar alloy systems.

Keywords: Hydrogen embrittlement; Austenitic Steel; Manganese Aluminium Alloys; Density Functional Theory; Crystal Orbital Hamilton Population