Perspectives on Novel Refractory Amorphous High-Entropy Alloys in Extreme Environments

TL;DR

This paper explores the design and stability of novel refractory amorphous high-entropy alloys under extreme conditions, demonstrating that chemical complexity and microstructure tuning can enhance their performance in high-temperature and irradiation environments.

Contribution

It introduces new RAHEAs in W--Ta--Cr--V and W--Ta--Cr--V--Hf systems, showing how Hf addition stabilizes the alloys under extreme conditions and reveals microstructural effects like nanoprecipitate reassembly.

Findings

Hf addition stabilizes RAHEA under annealing and irradiation.

Nanoprecipitate reassembling enhances radiation response.

Tunable chemical complexity improves alloy stability.

Abstract

Two new refractory amorphous high-entropy alloys (RAHEAs) within the W--Ta--Cr--V and W--Ta--Cr--V--Hf systems were herein synthesized using magnetron-sputtering and tested under high-temperature annealing and displacing irradiation using \textit{in situ} Transmission Electron Microscopy. While the WTaCrV RAHEA was found to be unstable under such tests, additions of Hf in this system composing a new quinary WTaCrVHf RAHEA was found to be a route to achieve stability both under annealing and irradiation. A new effect of nanoprecipitate reassembling observed to take place within the WTaCrVHf RAHEA under irradiation indicates that a duplex microstructure composed of an amorphous matrix with crystalline nanometer-sized precipitates enhances the radiation response of the system. It is demonstrated that tunable chemical complexity arises as a new alloy design strategy to foster the use of novel RAHEAs within extreme environments. New perspectives for the alloy design and application of chemically-complex amorphous metallic alloys in extreme environments are presented with focus on their thermodynamic phase stability when subjected to high-temperature annealing and displacing irradiation.