Energetics of Hydrogen Segregation to alpha-Fe Grain Boundaries for Modeling Stress Corrosion Cracking

M Rajagopalan and I Adlakha and MA Tschopp and KN Solanki, JOM, 69, 1398-1403 (2017).

DOI: 10.1007/s11837-017-2386-7

The physics of embrittlement is dictated by the various interactions between the impurities/defects and the local structure in polycrystalline material systems. In this study, a physically motivated model that describes the degree of interaction of hydrogen (H) defects on the segregation behavior to alpha-Fe grain boundaries (GBs) is developed. Molecular statics simulations were performed to quantify the segregation behavior of 1-2 H atoms at various interstitial sites around the < 100 >, < 110 >, < 111 >, and < 112 > symmetric tilt GBs. The results provide insights into the concentration profile of hydrogen defects along different GBs. Furthermore, the model accurately links the intrinsic GB character by quantifying the segregation length scale for the individual GBs based on the segregation behavior of defects. Finally, the metrics provided in this work are essential to comprehensively understanding the effect of hydrogen on the macroscopic behavior of alpha-Fe.

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