Thermodynamic properties over <UAl2(cr)+U(cr)> two phase region of U-Al system: Knudsen Effusion Mass Spectrometric study

•High temperature vaporisation thermodynamic studies over two-phase region of U-Al system were carried out using Knudsen Effusion Mass Spectrometry in the temperature range 1146-1327 K.•Partial pressure-Temperature (p-T) relation of Al(g) over this two phase region was deduced and ΔrH298.15∘ ∆fHm,GdAls,298.15K°of the reaction (UAl2(cr) = 2Al(g) + U(cr)) was evaluated by II and III law methods.•ΔfHm,UAl2(s),298.15∘ and ΔfGm,UAl2(s),298.15∘ were deduced and compared with the literature data. High temperature vaporisation thermodynamic studies over two-phase region of U-Al system were carried out by employing Knudsen Effusion Mass Spectrometry (also known as High Temperature Mass Spectrometry) in the temperature range of 1146-1327 K. The vaporisation reaction occurs incongruently and Al(g) was the neutral vapour species observed in the equilibrium vapour. Partial pressure-temperature relation of Al(g) was derived as log(pAl/Pa) = (−19809 ± 209)/T + (12.58 ± 0.17). Using the p˗T relation, ΔrH298.15∘ of the following reaction: UAl2(cr) = 2Al(g) + U(cr) was evaluated by second and third law methods. Subsequently, enthalpy and Gibbs energy of formation of UAl2(cr) were deduced as ΔfH298.15∘ = −89.9 ± 24.1 kJ mol−1 and ΔfG298.15∘= −89.9 + 24.1 kJ mol−1, respectively. The vaporisation studies on this two phase region are being reported for the first time.