Enhancing mechanical properties of NbZrMo alloy by maximizing configurational entropy from first-principles calculations

Mahdi Rizvandi,Ali Sadeghi

doi:10.1063/5.0057624

Abstract

High entropy alloys have been widely studied due to their unique physical properties compared to pure metals or conventional alloys with a single principal metallic component. We use ab initio calculations as the most prominent approach to investigate physical properties of materials to study mechanical properties of random ternary alloys NbZrMo. The equation of state and energy–stress relations are fitted to the ground-state energies from density functional theory calculations on structures with randomly arranged atoms on the crystallographic positions of the simple lattices. Among a couple of factors that determine the entropy of structure we consider the configuration that has the main effect on entropy at low temperatures. Several mechanical parameters and moduli are evaluated, and their dependence on the alloy composition is studied. We show that the alloy with the highest configuration entropy possesses the largest Young’s and bulk modulus values. The enhancement of other mechanical properties is also observed.

Highlights

In 2004, two different groups proposed a novel class of material with unique and extraordinary physical properties: High Entropy Alloys (HEAs).1,2 Soon, HEAs attracted the attention of scientists and engineers and found numerous applications: from use in spacecraft to the nuclear industry for irradiation damage resistance.3 HEAs have shown multiple practical and useful physical properties: enhanced thermoelectric performance,4 high strength while being light,5 special electronic and magnetic properties such as the anomalous Hall effect,6 and superconducting ability,7 to name but a few
Special Quasi-random Structure (SQS) is a Monte Carlo-based approach that ensures that maximum scitation.org/journal/adv entropy of the atomic arrangement is gained for the given composition while keeping the cell size as small as possible
Energies of the structures and their replicas that are slightly deformed from the equilibrium are obtained by ground-state Density Functional Theory (DFT) calculations

Summary

Introduction

In 2004, two different groups proposed a novel class of material with unique and extraordinary physical properties: High Entropy Alloys (HEAs). Soon, HEAs attracted the attention of scientists and engineers and found numerous applications: from use in spacecraft to the nuclear industry for irradiation damage resistance. HEAs have shown multiple practical and useful physical properties: enhanced thermoelectric performance, high strength while being light, special electronic and magnetic properties such as the anomalous Hall effect, and superconducting ability, to name but a few. HEAs have shown multiple practical and useful physical properties: enhanced thermoelectric performance, high strength while being light, special electronic and magnetic properties such as the anomalous Hall effect, and superconducting ability, to name but a few. Their phase stability and unique electrical and mechanical properties can be affected by the magnetic order, which makes them interesting in finding out the role of magnetism in phase stability and the contribution of each specific element. Some empirical factors have been suggested to make use of several design parameters to seek phase formation and crystal structure of HEAs, including atomic size mismatch δ, mixing entropy ΔSmix and enthalpy ΔHmix, valence electron concentration (VEC), and electronegativity mismatch..

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