The phase equilibria in the Au–In–Ga ternary system

Abstract

The phase equilibria of the Au-In-Ga system were investigated for the first time using Differential Thermal Analysis (DTA), X-Ray Diffractometry (XRD), Energy Dispersive Xray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM). A new ternary phase (Au 2 InGa 2 ) with the hexagonal structure (P6 3 /mmc) was discovered which melts incongruently at 394 C. From the experimental results, several invariant reactions have been identified and discussed.

The thermodynamic assessment of the Au–In–Ga system

“…• C. Some level of ternary solubility in the binary phases was also observed [7]; thus showing the need for adding interaction parameters to include solubility terms for the corresponding binary phases.…”

“…Cub, Fm-3m a = 0.60758 Au-Ga: [13] 66.7 at.%Ga Au-In-Ga: [7] Solubility of about 5.5 at.%In Cub, Fm-3m a = 0.6515 Au-In: [10] 66.7 at.%In Au-In-Ga: [7] Solubility of about 9.5 at.%Ga…”

“…Very recently an experimental investigation was published [7] related to an isothermal section of the Au-In-Ga phase diagram at 280…”

“…The description of the chosen thermodynamic models as well as the corresponding Gibbs energy functions and the interaction parameters will be explained later. Orth, --Au-Ga: [14] 29.8 − 31 at.%Ga AuGa Orth, Pnma a = 0.63971 Au-Ga: [13] 4 c = 0.34630 Au-In-Ga: [7] Solubility of about 3.0 at.%In…”

“…The role of group V elements has been ignored in this first step, since the solubility of the group V elements of our interest (As and P) in Au is negligible. The AuIn-Ga system has been assessed using the CALPHAD technique [6] based on the recent experimental evidence [7], resulting in a complete thermodynamic description.…”