Predicting Ti-Al Binary Phase Diagram with an Artificial Neural Network Potential

TL;DR

This paper develops a neural network interatomic potential for the Ti-Al binary system that accurately predicts phase boundaries, elastic properties, and stacking fault energies, improving modeling of phase transformations and plasticity.

Contribution

It introduces a rapid artificial neural network potential that reproduces the Ti-Al phase diagram and phase transitions with near-DFT accuracy, addressing limitations of classical and existing ML potentials.

Findings

Accurately predicts Ti-Al phase diagram up to 50% Al

Reproduces phase transition points between $ ext{α}$, $ ext{β}$, and D0$_{19}$ phases

Provides elastic constants and stacking fault energies close to DFT results

Abstract

The microstructure of the Ti-Al binary system is an area of great interest as it affects material properties and plasticity. Phase transformations induce microstructural changes; therefore, accurately modeling the phase transformations of the Ti-Al system is necessary to describe plasticity. Interatomic potentials can be a powerful tool to model how materials behave; however, existing potentials lack accuracy in certain aspects. While classical potentials like the Embedded Atom Method (EAM) and Modified Embedded Atom Method (MEAM) perform adequately for modeling dilute Al solute within Ti's $\alpha$ phase, they struggle with accurately predicting plasiticity. In particular, they struggle with stacking fault energies in intermetallics and to some extent elastic properties. This hinders their effectiveness in investigating the plastic behavior of formed intermetallics in Ti-Al alloys. Classical potentials also fail to predict the $\alpha$ to $\beta$ phase boundary. Existing machine learning (ML) potentials reproduce the properties of formed intermetallics with density functional theory (DFT) but do not examine the $\alpha$ to $\beta$ or $\alpha$ to D0$_{19}$ phase boundaries. This work uses a rapid artificial neural network (RANN) framework to produce a neural network potential for the Ti-Al binary system. This potential is capable of reproducing the Ti-Al binary phase diagram up to 50$\%$ Al concentration. The present interatomic potential ensures stability and allows results near the accuracy of DFT. Using Monte Carlo simulations, RANN potential accurately predicts the $\alpha$ to $\beta$ and $\alpha$ to D0$_{19}$ phase transitions. The current potential also exhibits accurate elastic constants and stacking fault energies for the L1$_0$ and D0$_{19}$ phases.