Thermochemical behavior of gallium-lithium alloy in gas and vapor-gas environments: A comprehensive study using thermal and mass spectrometric analysis

This paper presents the results of a comprehensive study of the interaction of gallium-lithium alloy with composition Ga 64 Li 36 with various gas and vapor-gas environments (Ar, Ar+H 2 , Ar+D 2 , Ar+H2O, Ar+D 2 O) in the temperature range of 100 °C - 900 °C. The investigations were conducted using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mass spectrometry (MS) on a specialized TiGrA complex. It was established that in inert (Ar, He) and hydrogen-containing environments (Ar+H 2 , Ar+D 2 ), the alloy maintains stability up to 600 °C, with reversible dissolution of hydrogen isotopes observed without significant mass change. The dissolution enthalpy is ΔH sol ≈ +10 to +12 kJ/mol (endothermic), indicating a primarily physicochemical nature of the interaction. In the presence of water vapor (Ar+H 2 O/D 2 O) and oxygen (Ar+O 2 ), the alloy exhibits high chemical activity. At T ≥ 250 °C, intense oxidation of lithium begins with the formation of LiOH, accompanied by the evolution of H 2 /D 2 . At T > 500 °C, dehydration of LiOH occurs followed by its interaction with gallium to form LiGaO 2 , confirmed by X-ray diffraction analysis. The activation energy of oxidation in vapor-gas environment, calculated using the Kissinger method, is E a ≈ 90–100 kJ/mol, indicating a diffusion mechanism at the initial stage and a surface mechanism at later stages. In an inert atmosphere at T > 650 °C, selective evaporation of lithium is observed, leading to changes in alloy composition and reduction of its functional characteristics. The obtained results demonstrate the potential of Ga 64 Li 36 alloy for application in thermonuclear reactors and define critical temperature and gas conditions for its operation.