Phase Equilibria and Tie-Lined Compositions in a Ternary Ni-Al-Re System at 1423 K

Abstract

Phase equilibria and compositions with tie-lines between the δ-Re, γ, γ′, β, Ni2Al3 as well as Re2Al and ReAl3 phases in a ternary Ni-Al-Re system were investigated at 1423 K by heat-treating of Ar-arc-melted Ni-Al-Re alloys in vacuum for times up to 3600 ks, followed by water-quenching and concentration measurements of Ni, Al and Re across the cross sections by using electron probe micro-analyzer (EPMA). The tie-lined compositions (at%) of each phase are summarized as follows. The δ-Re phase tie-lined with the γ phase (81.9 at%Ni, 15.9 at%Al, and 2.2 at%Re) has 18.8 at%Ni, 0.1 at%Al, and 81.1 at%Re. The δ-Re phase tie-lined with the γ′ phase (77.0 at%Ni, 21.7 at%Al, and 1.3 at%Re) has 16.2 at%Ni, 0.3 at%Al, and 83.5 at%Re. The δ-Re phase tie-lined with the β phase (50.8 at%Ni, 49.1 at%Al, and 0.1 at%Re) has 5.9 at%Ni, 1.8 at%Al, and 92.3 at%Re. The Re2Al phase tie-lined with the β phase (45.8 at%Ni, 53.2 at%Al, and 1.0 at%Re) has 4.4 at%Ni, 33.4 at%Al, and 62.2 at%Re. The ReAl3 phase tie-lined with the Ni2Al3 phase (39.2 at%Ni, 60.7 at%Al, and 0.1 at%Re) has 6.2 at%Ni, 75.9 at%Al, and 17.9 at%Re at 1323 K. There is no ternary intermetallic compound in the Ni-Al-Re system at 1423 K. Solubility limits of Ni and Al in the δ-Re phase in binary alloy systems are 28.0 at%Ni and (0.1∼1.2)at%Al, respectively.