Tie-Line Compositions of the σ and (γ,δ) Phases in the Re-Cr-Ni System at 1573 K

Abstract

Compositions with tie lines between the and (; ) phases in a ternary Re-Cr-Ni system were investigated by heat treating various ternary Re-Cr-Ni alloys at 1573 K in vacuum for up to 2000 h. The microstructures of the Re-containing alloys that had been water quenched after various heat treatment for times were observed and their concentration profiles for Re, Cr, and Ni were measured using an electron probe microanalyzer. The Re-Cr-Ni alloys consisted of the phase with either the or phase. The concentration profiles of the phase became flat after short heat treatment, whereas longer times of up to 2000 h were required to achieve the same effect for the and phases.The tie-line composition (at%) of each phase at 1573 K was experimentally determined as follows. The phase tie-line with the phase (17.3 Re, 20.6 Cr, and 62.1