Classical potential describes martensitic phase transformations between theα,β, andωtitanium phases

Abstract

A description of the martensitic transformations between the α, β and ω 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 α and β appears at ambient pressure and 1200 K, between α and ω at ambient conditions, between β and ω 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 α − ω transformation show a fast-moving interface with a low interfacial energy of 30 meV/ Å2 . The potential is applicable to the study of defects and phase transformations of Ti.

Ab initiobased empirical potential used to study the mechanical properties of molybdenum

“…21) and Ti (Ref. 22), and the EAM potential for Nb (Ref. 69), the simulated melting temperature for our Mo MEAM is in good agreement with the experimentally measured value.…”

“…The spline-based MEAM was successfully applied to study defects in Si 21,34-40 and martensitic phase transformations in Ti. 22 This success of the spline-based MEAM, its improved flexibility, and its higher computational efficiency motivate our use of this functional form here. The MEAM potential is implemented into two freely-available large-scale parallel molecular dynamics codes.…”

“…The modified embedded-atom method provides the form of the potential [20][21][22] with potential parameters optimized to a database of DFT calculations. The optimization of the model proceeds iteratively.…”

Central-force decomposition of spline-based modified embedded atom method potential

“…Currently s-MEAM parameterisations are available only for Mo [22], Ti [31] and Si [11,32]. The parameterisation for Ti has been particularly successful, with the ability to describe complex martensitic phase transformations between the α, β and ω phases of titanium.…”

“…At the same time its predictions for elastic constants, phonon frequencies, surface energies and defect formation energies are in very good agreement with results obtained at the density functional theory (DFT) level of theory. With the successes of [11,22,31,32] in mind, we anticipate an increase in the number of available parameterisations of s-MEAM in the near future.…”