Direct determination of γ' / γ'+γ / γ phase boundaries in Ni-Al-Cr system based on enthalpy of formation results obtained by calorimetric solution method

The work is a continuation of the research carried out on a high-temperature calorimeter solution type on alloys from Ni-Al-Cr system. Thanks to the construction innovation introduced by authors the device allows the determination of the formation enthalpy of alloys at ambient and elevated temperatures. Experiments described in this article were carried out at three temperatures: 873K, 996K and 1150K on the alloys of the chemical compositions from the Ni₇₅Al₂₅ ÷ Ni₈₇Cr₁₃ section of the Ni-Al-Cr system. On the basis of changes in the enthalpy of formation with increasing chromium content of the alloys, points corresponding to places of phase boundaries γ' / γ'+γ / γ in Ni-Al-Cr system were determined. A similar relationship was observed in previous studies of alloys from Ni₇₅Al₂₅÷Ni₇₅Cr₂₅ section. For precise determination of these characteristic points a statistical model was applied.