In-situ transmission electron microscopy investigation of the influence of hydrogen on the oxidation mechanisms of fine grained magnesium

X. Sauvage (1) , Simona Moldovan (1) , F. Cuvilly (1) , M. Bahri (2) , T. Grosdidier (3, 4)

1 GPM - Groupe de physique des matériaux
2 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
3 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
4 Labex DAMAS

Magnesium oxide is of critical importance for the properties of magnesium alloys designed for solid state storage of hydrogen. The oxidation of Mg was investigated by in-situ transmission electron microscopy under vacuum conditions and 105 Pa of H2 with a special emphasis on the influence of grain boundaries. In agreement with thermodynamic predictions, nucleation and growth of MgO was observed in both conditions, but the mechanisms and the corresponding kinetic are very different. Under vacuum it is assisted by Mg sublimation and relatively fast, while under H2 the oxidation proceeds slowly along grain boundaries that act as nucleation sites.

Keywords: Magnesium; Hydrogen; In-situ microscopy; Grain boundaries; Oxidation

Domains: Physics [physics]; Condensed Matter [cond-mat]; Materials Science [cond-mat.mtrl-sci]

X. Sauvage, Simona Moldovan, F. Cuvilly, M. Bahri, T. Grosdidier. In-situ transmission electron microscopy investigation of the influence of hydrogen on the oxidation mechanisms of fine grained magnesium. Materials Chemistry and Physics, 2020, 248, pp.122928. ⟨10.1016/j.matchemphys.2020.122928⟩. ⟨hal-02521105⟩