Microstructural and phase equilibria study in the Ni–Al–Cr–W system at 1173 and 1273 K

Several alloys of the Ni–Al–Cr–W quaternary system were prepared and their microstructure was studied quantitatively after long-term annealing at 1173 and 1273 K using scanning and transmission electron microscopy with energy-dispersive X-ray analysis. Thermodynamic modelling of the system was done by means of the Thermo-Calc software package. The thermodynamic parameters for the calculations were taken from commercial database for Ni-base superalloys. Two sections of quaternary phase diagrams at 1173 and 1273 K with constant Ni level of 71 and 76 at.% were discussed. Based on the comparison of our new experimental data with the results of thermodynamic modelling, a necessity of adjustment of some thermodynamic parameters was stated. Two of the interaction parameters describing the Ni–Al–W ternary subsystem were adjusted and better agreement of calculations with experiments was attained.