Abstrakt
The heat capacity of the Al(3)Ni phase had been measured for the first time, by means of relaxation method over the low temperature range 2-323 K and by measuring heat content increments using drop calorimetry over the higher temperature range of 583-1073 K. The Debye function was employed to fit the low-temperature heat capacities, and from the function, the absolute entropy was evaluated, S degrees(298) = 25.4 J/mol-atoms K.
A three-term polynomial representation, a + b.T + c.T(-2), was used for describing heat capacity above 298.15 K. The Gibbs energy function of the Al(3)Ni phase was derived with a fixed reference state by incorporating the polynomial expression of the heat capacity, the recently reported enthalpy of formation and the related phase equilibria in the Al-Ni system.
A revised thermodynamic description of the entire Al-Ni system together with the calculated phase diagram is also presented.