Force-matched empirical potential for martensitic transitions and plastic deformation in Ti-Nb alloys

Abstract

A force-matched spline-based empirical potential based on the modified embedded-atom method is fit to an extensive database of highly-converged density functional theory calculations for titaniumniobium alloys with an evolutionary algorithm. Consistency with experiment and existing models is verified through calculations of structural, elastic and thermal properties. The potential is used to study the effects of alloying on elastic properties, the martensite phase of Ti-rich alloys and the α-β and β-ω transformations. Stress-and temperature-induced martensitic transitions are demonstrated in Ti-25 at.%Nb by NPT simulation. Last, the effect of alloying on screw dislocations in hcp-Ti and bcc-Nb is analyzed at 5 at.% solute content with the fitted potential.

Capturing anharmonic and anisotropic natures in the thermotics and mechanics of Bi2Te3 thermoelectric material through an accurate and efficient potential

“…Therefore we highlight that all the calculated properties must be derived from reasonable simulated configurations in the current conditions, which in turn are powerful indicators that will 'spontaneously' select suitable potential forms and parameters, obeying the basic logic that FF modeling is actually the inverse problem of the corresponding simulation. This is essential for all FF study involving potential development [136,137] and modification [138][139][140][141][142].…”

Studying Plastic Deformation Mechanism in β-Ti-Nb Alloys by Molecular Dynamic Simulations

“…To further substantiate the presence of the interfacial ω-phase, additional analysis was conducted on the grain boundary orientations, as depicted in Figure 6. Substructures c and d in Figure 6a correspond to those in Figures 6c and 6d Lai et al [48] and Ehemann et al [51] also calculated the energy change from the phase to the ω-phase of Ti-Nb alloys. They determined that the ω-phase structure p sesses lower energy compared to the β-phase.…”

Phase transitions in titanium with an analytic bond-order potential

“…The details of the hexagonal transformation path can be found in Refs. 50, 90, and 91; the bcc → ω transition consists of a shuffling of pairs of atoms along the [111] direction of bcc, corresponding to the 2 3 [111] phonon 23 . For simplicity, the volume of the unit cell was taken as constant along the transformations.…”

“…For instance, it has been reported that an accurate description of the ω phase [14][15][16][17][18][19] or of the temperature-dependent behavior of the bcc phase [20,21] needs to be sacrificed to achieve an overall good accuracy of the potential. A few potentials have succeeded to reproduce at least the α, β, and ω phases quantitatively [22][23][24] by increasing the model complexity and by employing non-smooth interpolators, which however might lead to overfitting. The transferability of these more complex potentials to properties or environments not included in the training has been questioned [18,25].…”

“…To further test the BOP, we calculated the energy along the hexagonal and bcc w  transformation paths with DFT and with the present BOP, since these paths are crucial for the phase transitions in Ti. The details of the hexagonal transformation path can be found in [50,91,92]; the bcc w  transition consists of a shuffling of pairs of atoms along the [111] direction of bcc, corresponding to the 111 2 3 [ ] phonon [23]. For simplicity, the volume of the unit cell was taken as constant along the transformations.…”