High-entropy ceramic thin films; A case study on transition metal diborides

TL;DR

This study demonstrates that high-entropy transition metal diborides exhibit increased hardness and enhanced thermal stability compared to lower-entropy variants, highlighting their potential for advanced ceramic applications.

Contribution

It provides the first detailed investigation into high-entropy diborides, showing improved hardness and thermal stability over traditional compositions.

Findings

Hardness increased from 43.2 to 47.2 GPa in high-entropy diborides.

High-entropy diborides show superior thermal stability.

Formation of solid solutions enhances material properties.

Abstract

High-entropy materials often outperform their lower-entropy relatives in various aspects, such as thermal stability and fracture toughness. While there are extensive research activities in the field of high-entropy alloys, comparably little is performed for high-entropy ceramics, and especially for high-entropy diborides. Here we show, that not only the hardness of ZrB2 layers can be improved from 43.2 to 45.8 to 47.2 GPa through the formation of solid solution ternary diborides (Zr0.61Ti0.39B2) and high-entropy diborides (Zr0.23Ti0.20Hf0.19V0.14Ta0.24B2), respectively, but especially their thermal stability against structural rearrangements and decomposition towards the constituting binary diborides.