TCHEA1: A Thermodynamic Database Not Limited for “High Entropy” Alloys

Abstract

In this paper we report a thermodynamic database which was developed by using the CALPHAD approach. The TCHEA1 database includes 15 chemical elements (Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Ta, Ti, V, W and Zr). It is suitable for the study of Bcc and Fcc HEA systems. The database is constructed based on the thermodynamic assessment of all binary systems and many key ternary systems where almost all possible metastable and stable phases are considered. It is extensively demonstrated in the present work that TCHEA1 gives satisfactory prediction on the phase equilibria in various HEA systems (quaternary to ennead) and wide temperature ranges (liquidus to subsolidus). Thermodynamic stability calculations of simple solid solutions (Bcc and Fcc) and intermetallics (sigma, Laves, l-phase etc.) are validated against the available experimental information in as-cast or as-annealed state. Such CALPHAD database focusing on the modelling of Gibbs energy rather than entropy makes reliable predictions of thermodynamic equilibrium and phase transformation, no matter whether the alloy/system has high entropy or not. Cases with miscibility gap in liquid and solid solutions and second-order phase transition at low temperatures are demonstrated. With the volume data included, TCHEA1 is capable to predict the density and thermal expansion coefficient of HEAs as well. This thermodynamic database is also applicable in process simulations when used together with compatible kinetic databases.

Mechanical and Thermal Properties of Low-Density Al20+xCr20-xMo20-yTi20V20+y Alloys

“…The database used in this software was Thermo-Calc's high-entropy alloy (TCHEA1) database [18]. The phase prediction based on the TCHEA1 database was in good agreement with many experimental reports [19][20][21][22]. The first-principles method used in this study was based on DFT [23,24].…”

Modeling the structure and thermodynamics of high-entropy alloys

“…Finally, the convex hull is computed over a desired range of compositions and temperatures. Several companies offer databases and associated software tools, notably PANDAT and Thermo-Calc, 93 each of which have developed databases geared toward the study of HEAs. There is also an open source effort.…”

Integrated computational materials engineering of corrosion resistant alloys

“…1 CALPHAD-predicted phase diagram for an HEA Al x CoCrFeNi above~700°C. This diagram was calculated using the Thermo-Calc HEA database 107 and is used to guide design of the processing of an HEA, specifically the compositional boundaries of the single phase FCC HEA (highlighted in green) and the temperatures in which postcast heat treatment (such as homogenization) can be applied (any temperature above the FCC + B2 solvus and below the FCC + Liquid solidus)…”