Thermodynamic assessment and experimental investigation of the Li-Sn system

The Li-Sn phase diagram was re-investigated using differential thermal analysis (DTA). A special thermal analysis technique was used to clarify the characters of the invariant reactions between the liquid, Li17Sn4 and Li7Sn2 phases and between the liquid, Li7Sn2 and Li13Sn5 phases. Using this technique, the eutectic reaction: L↔Li17Sn4+Li7Sn2 and the peritectic reaction: L+Li7Sn2↔Li13Sn5 were confirmed. The enthalpy of formation of the Li17Sn4 phase was measured using high temperature solution calorimetry. A self-consistent thermodynamic description of the Li-Sn system was developed using the CALPHAD method. The liquid phase was described using the associate model, the Li17Sn4, Li13Sn5, Li5Sn2, Li7Sn3, LiSn and Li2Sn5 phases were modeled as stoichiometric compounds, and the Li7Sn2 phase was modeled to exhibit a homogeneity range at higher temperatures. Phase diagrams and property diagrams calculated using the new thermodynamic description for the Li-Sn system are in good agreement with the experimental data performed in this work and with literature data.