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

摘要

A description of the martensitic transformations between the $\alpha$,$\beta$ and $\omega$ phases of titanium that includes nucleation and growthrequires an accurate classical potential. Optimization of the parameters of amodified embedded atom potential to a database of density-functionalcalculations yields an accurate and transferable potential as verified bycomparison to experimental and density functional data for phonons, surface andstacking fault energies and energy barriers for homogeneous martensitictransformations. Molecular dynamics simulations map out thepressure-temperature phase diagram of titanium. For this potential themartensitic phase transformation between $\alpha$ and $\beta$ appears atambient pressure and 1200 K, between $\alpha$ and $\omega$ at ambientconditions, between $\beta$ and $\omega$ at 1200 K and pressures above 8 GPa,and the triple point occurs at 8GPa and 1200 K. Molecular dynamics explorationsof the dynamics of the martensitic $\alpha-\omega$ transformation show afast-moving interface with a low interfacial energy of 30 meV/\AA$^2$. Thepotential is applicable to the study of defects and phase transformations ofTi.