Classical potential describes martensitic phase transformations between the $\alpha$, $\beta$ and $\omega$ titanium phases

TL;DR

This paper develops a classical potential for titanium that accurately models martensitic phase transformations among its $ ext{α}$, $ ext{β}$, and $ ext{ω}$ phases, enabling detailed molecular dynamics simulations of phase behavior.

Contribution

It introduces a modified embedded atom potential optimized with density-functional data, providing a transferable tool for simulating titanium's phase transformations and defect behaviors.

Findings

The potential accurately reproduces experimental and DFT data for phonons, surfaces, and stacking faults.

It maps the phase diagram of titanium, identifying phase boundaries and the triple point.

Simulation reveals a fast-moving interface with low interfacial energy during the $ ext{α}- ext{ω}$ transformation.

Abstract

A description of the martensitic transformations between the $\alpha$, $\beta$ and $\omega$ phases of titanium that includes nucleation and growth requires an accurate classical potential. Optimization of the parameters of a modified embedded atom potential to a database of density-functional calculations yields an accurate and transferable potential as verified by comparison to experimental and density functional data for phonons, surface and stacking fault energies and energy barriers for homogeneous martensitic transformations. Molecular dynamics simulations map out the pressure-temperature phase diagram of titanium. For this potential the martensitic phase transformation between $\alpha$ and $\beta$ appears at ambient pressure and 1200 K, between $\alpha$ and $\omega$ at ambient conditions, between $\beta$ and $\omega$ at 1200 K and pressures above 8 GPa, and the triple point occurs at 8GPa and 1200 K. Molecular dynamics explorations of the dynamics of the martensitic $\alpha-\omega$ transformation show a fast-moving interface with a low interfacial energy of 30 meV/\AA$^2$. The potential is applicable to the study of defects and phase transformations of Ti.