Thermodynamic Modeling of the Au-Bi-Sb Ternary System

Abstract

Based on the available experimental information, the Au-Bi binary system has been thermodynamically assessed using the CALPHAD method. The solution phases, including liquid, fcc_A1, and rhombohedral_A7, were modeled as substitutional solutions, while the intermediate compound Au 2 Bi was described as a stoichiometric compound. Combined with the available thermodynamic parameters of the Au-Sb and Bi-Sb binary systems, a thermodynamic description of the Au-Bi-Sb ternary system has been developed to reproduce the reported phase equilibria. The liquidus projection and several vertical and isothermal sections of this ternary system have been calculated, which are in reasonable agreement with the reported experimental data.

Verification of Phase Diagrams by Three-Dimension Computer Models

“…The results of experimental study and thermodynamic correlation using the CALPHAD-technology of the Au-Bi-Sb=A-B-C system with the compounds Au 2 Bi=R 1 and AuSb 2 =R 2 , are presented in [25,26]. Earlier six isopleths had been shown in [27], which then were also constructed in [26].…”

“…Earlier six isopleths had been shown in [27], which then were also constructed in [26]. The authors of atlas [12] after the analysis of these publications preferred the results of the data of [26], but correcting and obtaining "the better agreement in comparison with the experimental results". The region of the homogeneity of the solid solution Bi(Sb)=B(C) is shown in [26] in the isothermal section 300°C.…”

“…The authors of atlas [12] after the analysis of these publications preferred the results of the data of [26], but correcting and obtaining "the better agreement in comparison with the experimental results". The region of the homogeneity of the solid solution Bi(Sb)=B(C) is shown in [26] in the isothermal section 300°C. Analogous section is used for the illustration of the phase diagrams calculation results by the method of the convex hulls [28].…”

“…But the single-phase region RHOMBO_A7 would then be adjacent to three-phase regions Bi (Sb)+Au 2 Bi+AuSb 2 =B(C)+R1+R2(RHOMBO_A7+AU2BI_ C15+AUSB2) and L+Bi(Sb)+AuSb 2 =L+B(C)+R2 (L+RHOMBO_ A7+AUSB2is not designed in [12], violating the law of adjoining phase regions. As was mentioned above, authors of [12] preferred the results of the work [26]. It is necessary to note that the binary system Bi-Sb is examined in [26] at temperatures above 500 K -above the binodal curve and the temperature 400 K is the minimum in all isopleths.…”

“…As was mentioned above, authors of [12] preferred the results of the work [26]. It is necessary to note that the binary system Bi-Sb is examined in [26] at temperatures above 500 K -above the binodal curve and the temperature 400 K is the minimum in all isopleths. The disintegration cupola of the solid solution Bi(Sb) is absent in the sections, published in [26], and it is possible only to assume that it would appear at temperatures below 400 К.…”