Determination of γ +γ / γ phase boundary in ni-al-cr system using dta thermal analysis

Mechanical properties at elevated temperature, in modern alloys based on intermetallic phase Ni3Al are connected with phase composition, especially with proportion of ordered phase γ (L12) and disordered phase γ (A1). in this paper, analysis of one key systems for mentioned alloys - Ni-Al-Cr, is presented. A series of alloys with chemical composition originated from Ni-rich part of Ni-Al-Cr system was prepared. DTA thermal analysis was performed on all samples. Based on shape of obtained curves, characteristic for continuous order-disorder transition, places of course of phase boundaries γ +γ / γ were determined. Moreover, temperature of melting and freezing of alloys were obtained. Results of DTA analysis concerning phase boundary γ +γ / γ indicated agreement with results obtained by authors using calorimetric solution method. Keywords: DTA thermal analysis, order-disorder transition, Ni₃Al, Ni-Al-Cr.