Effect of the Pt concentration on microstructures of Ti-Pt alloys using the first-principles phase field method

The effect of the Pt concentration on microstructures of Ti-Pt alloys is studied by the first-principles phase field (FPPF) method, which enables us to investigate the evolution of microstructures from first principles without using thermodynamic empirical parameters. The method first constructs the local free energy, which is needed in the phase field simulation, by combining density functional theory, cluster expansion theory including atomic vacancies, and potential renormalization theory. Applying this FPPF method to Ti1-xPtx alloys at 800 degrees C, we have confirmed that increasing the Pt concentration as 5, 10, 15 and 20 wt% causes a drastic change in the microstructure of Ti-Pt alloys in accord with the experimental observation by Song et al. (Materials 7 (2014) 3990). In the case of the Pt concentration less than 10 wt%, the microstructure is lamellar- or wavy-shaped everywhere. When the Pt concentration is 15 and 20 wt%, spot-like Ti3Pt precipitates appear in the alpha-Ti phases with lamellar- or wavy-shaped patterns. These results are confirmed in both 2D and 3D simulations. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The effect of Pt concentration on microstructures of Ti-Pt alloys was studied using the first-principles phase field method. Increasing Pt concentration led to drastic changes in the microstructure of the alloys. Microstructures were lamellar- or wavy-shaped when Pt concentration was less than 10 wt%, and spot-like Ti3Pt precipitates appeared in alpha-Ti phases with lamellar- or wavy-shaped patterns at 15 and 20 wt% Pt concentration.