Experimental Study of the Phase Diagram of the La-Ni–Sn System at 300 and 600  °C

The phase equilibria of the ternary La-Ni–Sn system have been experimentally studied at temperatures of 300 and 600 °C using long-term annealed samples. The coexisting phases were characterized by scanning electron microscopy SEM and powder X-ray diffraction XRD. The phase transformation temperatures were analyzed using thermal analysis DTA or DSC methods. The LaNi5 phase, which is known as a hydrogen storage material, was observed to have up to 10% tin solubility at 600 °C. At a temperature of 300 °C, there is a region of miscibility gap between 1.9 and 6.5 at% Sn which is no longer present at 600 °C. Twelve ternary intermetallic phases were found at 300 °C and eleven ternary intermetallic phases at 600 °C. None of them showed a noticeable homogeneity range. Based on the experimental data obtained, isothermal sections of the La-Ni–Sn phase diagram were constructed at 300 and 600 °C.