Thermochemical properties of ternary Si-Ni-Al liquid alloys

Partial (for aluminum) and integral mixing enthalpies of ternary Si-Ni-Al liquid alloys are examined by high-temperature calorimetry under isoperibolic conditions at 1770 ± 5 K. Alloys of five radial sections with a constant ratio of silicon-to-nickel mole fractions (x_Si/x_Ni = 0.85/0.15; 0.7/0.3; 0.5/0.5; 0.3/0.7, and 0.15/0.85) within the interval compositions to aluminum mole fraction x_Al ∼ 0.6 are studied. The mixing enthalpies of Si-Ni-Al alloys are characterized by great exothermal values. Exothermal partial enthalpies of aluminum mixing increase at infinite dilution with increasing nickel concentration in starting binary alloys ( reaches −17.0 ± 3.3 kJ/mole for section with x_Si/x_Ni = 0.85/0.15 and −119.0 ± 11.2 kJ/mole for x_Si/x_Ni = 0.15/0.85). An analysis of alloy-formation energy parameters in the ternary Si-Ni-Al system indicates that the interaction of the components in the bounded binary Si-Ni and Ni-Al systems greatly contributes to Δ_mH, the effect of the former prevailing. The thermochemical properties of ternary alloys and of Ge-Ni-Al melts and simulated mixing enthalpies of ternary Sn (C)-Ni-Al liquid alloys are compared. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 79–85, 2007.