| Alloys involving Ni, Al and other elements are of interest for applications such as high temperature structural materials for gas turbines. Alloy development of such materials requires a thorough knowledge of the thermodynamic properties and phase equilibria in the binary, ternary and higher order alloy systems. Precise determinations of thermodynamic properties, especially enthalpy of formation, are valuable for obtaining an accurate thermodynamic model of a multicomponent system.; In order to understand fundamental thermodynamic properties and the systematics between alloys, Al-Ni-Y, Al-Ni-Fe and Al-Ni-Ru were selected for studying enthalpy of formation, lattice parameter and also alloying behavior through correlations between the heat of formation and other physical properties.; Partial isothermal section of Al-Ni-Y in a range of Y ≤ 0.33 at. % at 650°C was measured and Al3Ni2Y, Al7Ni3Y2, Al23Ni6Y4 have been confirmed to be the existing compounds. Site occupancy as well as atomic volume in B2 phase field of Al-Ni-Fe system have been studied in order to understand more about the alloying behavior. The existence of the miscibility gap between the B2 phase field across AlNi and AlRu in AlNi-Ru system has also been studied using enthalpy and lattice parameter results.; Extended Miedema's semi-empirical model has been used to predict enthalpy of formation of ternary compounds in selected ternary systems. The difference between the predicted and experimental results will be correlated to a factor which is required to be taken into consideration when upgrading the binary based Miedema model to ternary compound application. |
