Experimental investigation and thermodynamic analysis of the Sc-Ni system supplemented with first-principles calculations

The Sc-Ni binary system was investigated via a hybrid of experiment and thermodynamic calculation. Eleven alloys were prepared by arc melting. The as-cast and annealed samples were analyzed by means of X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectrometer, electron probe microanalysis and differential thermal analysis/differential scanning calorimetry. The invariant reactions on Sc-rich side were reinvestigated. Five compounds (ScNi₅, Sc₂Ni₇, ScNi₂, ScNi and Sc₂Ni) were observed in the present experiment. Their enthalpies of formation at 0 K were computed via first-principles calculations to supply referable thermodynamic data for the modeling. One single function was used to describe the Gibbs energies of both the ordered Bcc-B2 (ScNi) and disordered Bcc-A2 phases. The presently obtained thermodynamic parameters for the Sc-Ni system can reproduce the experimental data reasonably.