Thermodynamic assessment of the Cu-Ti-Zr system. I. Cu-Ti system

Abstract

The CALPHAD method is used for the thermodynamic assessment of the Cu-Ti system that bounds the ternary Cu-Ti-Zr system, which is capable of forming amorphous alloys. The self-consistent parameters of thermodynamic models of the phases are obtained from data on the phase equilibria and thermodynamic properties of liquid alloys and intermetallic compounds. The Gibbs energy of the liquid phase is described using the associated ideal solution model. To describe the thermodynamic properties of the Cu 4 Ti and CuTi intermetallic compounds with homogeneity range, sublattice models are used. The calculated phase diagram of the system and the thermodynamic properties of the phases are in good agreement with experimental data.

Characterization of the Si3N4/Si3N4 joints fabricated using particles modified braze

“…Estimation of Gibbs free energies for the formation of possible reaction phases between Ti and Cu were examined in the temperature range of 677-977 1C [32]. Considering only the thermodynamic information, the Gibbs free energies of formation for CuTi intermetallics were negative, indicating their existence in the brazing layer was reasonable.…”

Microstructure and mechanical properties of Si3N4/42CrMo joints brazed with TiNp modified active filler

“…The EDS results showed that these intermetallics were mainly composed of Cu and Ti elements. According to the Cu-Ti binary phase diagram [19], Cu can easily react with Ti thermodynamically to form Cu-Ti intermetallics owing to their strong mutual affinity, indicating that the displayed intermetallics were Cu-Ti compounds. However, Cu-Ti intermetallics were difficult to detect if less than 15 vol% TiNp was incorporated, as shown in Fig.…”

Thermodynamic assessment of the Cu-Ti-Zr system. III. Cu-Ti-Zr system

“…The parameters of models describing the thermodynamic properties of phases in the boundary binary systems are taken in accordance with our previous thermodynamic assessments: Cu−Ti [20], Cu−Zr, and Ti−Zr [21]. To describe the ternary Cu−Ti−Zr system, it was needed to model the properties of ternary nonstoichiometric phases: solid solutions based on pure components, liquid phase, binary intermetallic compounds for which homogeneity regions were found in the ternary system, and ternary intermetallide τ 1 .…”

“…In this formula, copper sublattice is the first and titanium sublattice is the second one; the main component in the corresponding sublattice is underlined. According to CEF, the temperatureconcentration dependence of the Gibbs energy of Cu k Me l , which has a homogeneity region in binary and ternary systems, per mole of atoms is described as follows: To describe CuTi in the Cu-Ti system, the sublattice formula (Cu, Ti) 1 : (Cu, Ti) 1 was used in [20]. To account for the solubility of zirconium in this compound in the Cu-Ti-Zr ternary system, the sublattice formula was modified on the assumption that zirconium may substitute titanium in its sublattice: (Cu, Ti) 1 : (Cu, Ti, Zr) 1 .…”

“…This conclusion is not surprising since it is shown in [27] that the contribution of ternary interaction to the mixing enthalpy of liquid Cu−Ti−Zr alloys is sign-changing and its absolute value is small. Therefore, we used only parameters of the formation of binary associates obtained in [20,21] in further calculations within the thermodynamic description of ternary melts.…”