Abstract:The enthalpies of formation of the ternary compounds Al₄NiY, Al₂NiY, Al₂Ni₆Y₃, Al₁₆Ni₃Y, AlNiY, Al₃Ni₂Y, AlNi₈Y₃, Al₇Ni₃Y₂, and of the binary compounds Al₂Y containing nickel and Ni₅Y containing aluminum have been determined by high temperature reaction calorimetry. The enthalpy values measured are compared to previously published results where available as well as extended Miedema model predict ions. The melting points of the compounds were determined by DTA and X-ray diffraction was used to confirm the crystal structures of the compounds. The enthalpies of formation of the ternary compounds show a maximum along the 50%Al (mole fraction) section. The ternary compounds appear along lines of constant yttrium content consistent with binary compound solubility extensions.

Key words: enthalpy of formation; compound; Al-Ni-Y system