Effect of zirconium doping on mechanical properties of $W_{1-x}Zr_xB_2$ on the base of ab initio calculations and magnetron sputtered films

TL;DR

This study combines first-principles calculations and experimental deposition to analyze how zirconium doping affects the mechanical properties of $W_{1-x}Zr_xB_2$, revealing stability, reduced hardness, and the influence of microstructure on strength.

Contribution

It provides a comprehensive analysis of zirconium doping effects on $W_{1-x}Zr_xB_2$ using both ab initio calculations and experimental film deposition, highlighting stability and property changes.

Findings

Zirconium doping reduces hardness and fracture toughness.

Deposited films show higher hardness but lower fracture toughness.

Microstructure changes and solid solution hardening contribute to strengthening.

Abstract

Potentially superhard $W_{1-x}Zr_xB_2$ polymorph hP6-P6$_3$/mmc-$WB_2$ with zirconium doping in the range of x=0.0-0.25 was thoroughly analyzed within the framework of first-principles density functional theory from the structural and mechanical point of view. The obtained results were subsequently compared with properties of material deposited by magnetron sputtering method. All predicted structures are mechanically and thermodynamically stable. Due to theoretical calculations zirconium doping reduces hardness and fracture toughness $K_{IC}$ of $WB_2$. Deposited films are characterized by greater hardness $H_v$ but lower fracture toughness $K_{IC}$. The results of experiments show that not only solid solution hardening is responsible for strengthening of predicted new material but also change of microstructure, Hall-Petch effect and boron vacancies.