First-principles calculation of the effect of Ti content on the structure and properties of TiVNbMo refractory high-entropy alloy

Abstract

The virtual crystal approximation (VCA) method based on the Cambridge Sequential Total Energy Package (CASTEP) was used to establish the TiVNbMo refractory high-entropy alloy structure model. The effects of different Ti contents on the elastic and thermodynamic properties of TixVNbMo (x = 1.00, 1.25, 1.50, 2.00) high entropy alloys were calculated. The lattice constants calculation results of TiVNbMo with equal atomic ratio match well with the experimental values of vacuum arc melting, indicating that the VCA method is suitable for the first-principles calculation of TixVNbMo random solid solution. The EOS equation of state is used to determine the energy and volume of the equilibrium structure of the alloy. The elastic constants of TixVNbMo (x = 1.00, 1.25, 1.50, 2.00) high entropy alloys are calculated based on the body-centered cubic structure, and their Young’s modulus anisotropic three-dimensional contour stereograms are drawn. Moreover, the quasi-harmonic Debyeg-Grüneisen model is used to calculate the thermodynamic properties, such as thermal capacity, isothermal body modulus, volumetric thermal expansion coefficient, and Grüneisen parameter with Ti content and temperature.

A review on high-throughput development of high-entropy alloys by combinatorial methods

“…VCA deals with this issue using a pseudopotential that averages the properties of each atom in different positions in the lattice cell. Ramer and Rappe previously investigated multiple methods to produce the averaged pseudo-potential such as averaging the pseudo-potentials for each atom within the lattice and averaging 'all-electron results' [103] . It was found that the averaging of 'all-electron results' provided the most accurate result when compared to experiments.…”

“…It was found that the averaging of 'all-electron results' provided the most accurate result when compared to experiments. This method involved averaging the Coulombic potentials and charge densities of the constituent atoms and then using these values to generate wavefunctions that are self-consistent solutions to the Kohn-Sham equation [103] .…”

Simulation and Calculation for Predicting Structures and Properties of High-Entropy Alloys

“…Liao et al [32] found that the lattice constant, elastic constant, and thermal expansion coefficient of NbTiVZr were in agreement with other calculations and experiments, confirming that the VCA scheme was suitable for random Nb-Ti-V-Zr systems. A similar study was conducted by Chen et al [14] which focused on the phase structure, elastic constants, and thermodynamic properties of Ti x VNbMo refractory high entropy alloy (RHEA) by the VCA in conjunction with the equation of state (EOS) equilibrium equation of state and the quasi-harmonic Deby-Grüneisen model. Researchers are involved in the exploration of new HEA systems suitable for use in the VCA.…”

“…In the material simulation, we can simulate the material from various scales, and qualitatively as well as quantitatively describe the characteristics of the material and promote our understanding of it from multiple perspectives. For materials with different scale-space, there are corresponding material calculation methods, including the firstprinciples density functional theory (DFT), molecular dynamics (MD), the calculation of phase diagram (CALPHAD), and high-throughput methods [13][14][15][16][17][18][19][20]. Hence, from the microscopic to the macroscopic scale, this chapter reviews the limitations and potentials of different simulation methods by summarizing in a targeted manner the characteristics and application areas of different simulation methods.…”

“…Researchers are involved in the exploration of new HEA systems suitable for use in the VCA. Gao et al [14] explored the elastic constants and elastic properties of VMoNbTaWM x (M = Cr, Ti) RHEA by using the first principle and VCA method. In addition, they found that, when Cr content was raised, the bulk modulus B, Young's modulus E, and the shear modulus G increased, while the Pugh ratio B/G and Poisson's ratio ν fluctuated to some extent.…”