Nickel-rich part of ternary system Ni-Al-Cr is crucial for currently used nickel superalloys and alloys based on intermetallic phase Ni3Al. Those materials are dedicated to work at elevated temperature and consist, among others, of ordered phase γ′ and disordered phase γ in different proportions. Therefore, it is essential to learn high temperature course of phase boundaries γ′/γ′+γ and γ′+γ/γ in Ni-Al-Cr system. Series of alloys, which chemical composition from the Ni75Al25 ÷ Ni65Cr35 section of discussed system, were prepared and were tested using high-temperature solution calorimeter. The device allows for determination of formation enthalpy of alloys at temperatures up to 1273 K. Formation enthalpy of alloys from Ni75Al25 ÷ Ni65Cr35 section was determined for three temperatures: 873 K, 996 K and 1150 K. On the basis of changes in the enthalpy of formation value with increase of chromium content in alloys, presence of characteristic points was found. It was assigned to phase boundaries γ′/γ′+γ and γ′+γ/γ. Likewise, it was similar to previous ranges tested by author which are: Ni75Al25 ÷ Ni75Cr25 and Ni75Al25 ÷ Ni87Cr13.Keywords: Solution calorimetry, enthalpy of formation, Ni-Al-Cr system, phase boundary
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