Calculation of the P-T phase diagram and tendency toward decomposition in equiatomic TiZr alloy

TL;DR

This study uses density functional theory and thermodynamic models to analyze the phase stability and decomposition tendencies of equiatomic TiZr alloy, revealing temperature-dependent phase stability and a tendency toward ordering over decomposition.

Contribution

It provides a comprehensive theoretical calculation of the TiZr phase diagram and stability, aligning well with experimental data and highlighting the alloy's ordering tendency.

Findings

Omega phase stable at low temperatures and atmospheric pressure

Alpha phase stable between 600K and 900K

Beta phase stable above 900K

Abstract

Electronic, structural and thermodynamic properties of the equiatomic alloy TiZr are calculated within the electron density functional theory and the Debye-Gruneisen model. The calculated values of the lattice parameters a and c/a agree well with the experimental data for the alpha, omega and beta phases. The omega phase is shown to be stable at atmospheric pressure and low temperatures; it remains energetically preferable up to T=600K. The alpha phase of the TiZr alloy becomes stable in the range 600K<T<900K, and the beta phase at temperatures above 900K. The constructed phase diagram qualitatively agrees with the experimental data available. The tendency toward decomposition in the equiatomic alloy omega-TiZr is studied. It is shown that in the ground state the omega phase of the ordered equiatomic alloy TiZr has a tendency toward ordering, rather than decomposition.