Ideal strength of random alloys from first-principles theory

TL;DR

This study uses first-principles calculations to determine the ideal tensile strengths of elemental V, Mo, and their alloys, revealing how alloying elements influence strength through electronic structure analysis.

Contribution

It introduces a first-principles approach combining the muffin-tin orbitals method and coherent-potential approximation to evaluate ideal strengths of random alloys.

Findings

V and Mo have direction-dependent ideal strengths consistent with theory.

Adding Tc decreases Mo's strength in the [001] direction.

Cr increases and Ti decreases the strength of V-based alloys.

Abstract

The all-electron exact muffin-tin orbitals method in combination with the coherent-potential appproximation has been employed to investigate the ideal tensile strengths of elemental V, Mo solids and V- and Mo-based random solid solutions. The present ideal tensile strengths, calculated assuming isotropic Poisson contraction, are 16.1, 26.7 and 37.6 GPa for bcc V in the [001], [111] and [110] directions, respectively, and 26.7 GPa for bcc Mo in the [001] direction, which are all in good agreement with the available theoretical data. When a few percent Tc is introduced in Mo, it is found that the ideal strength decreases in the [001] direction. For the V-based alloys, Cr increases and Ti decreases the ideal tensile strength in all principal directions. Adding the same concentration of Cr and Ti to V leads to ternary alloys with similar ideal strength values as that of pure V. The alloying effects on the ideal strength is explained using the electronic band structure.