Effect of Y2O3 addition on the microstructure and mechanical properties of an Al1.8CoCrCu0.5FeNi BCC HEA

The present study investigated the influence of Y2O3 addition by mechanical alloying (MA) on the micro-structure evolution of a BCC High Entropy Alloy (HEA). The characterisation and mechanical properties of the alloy were explored using X-ray diffraction, SEM, EBSD, and nano-indentation. The sintered Al1.8CoCrCu0.5FeNi HEA shows a microstructure formed by an ordered BCC phase (Al-rich) and a second disordered BCC (Cr-rich), while a minor FCC (Cu-rich) appears. These BCC phases show a wide morphology evolution from cuboidal and wave-like structures to irregular shapes. The minor FCC phase also adopts several morphologies as the MA is performed. The introduction of oxide reinforcements and microstructure refinement through mechanical alloying yields a change in phase quantification and grain structure. In accordance with the hardness and elastic modulus values from ordered/disordered BCC phases, the dis-ordered BCC shows higher values than the ordered one. The grain size reduction as well as the solid solution strengthening from the microstructure evolution consequence of the MA are shown to be the main con-tributors to the increase in hardness and elastic modulus in the consolidated samples. & COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Automated summary

The influence of Y2O3 addition by mechanical alloying on the microstructure evolution of a BCC High Entropy Alloy was investigated. X-ray diffraction, SEM, EBSD, and nano-indentation were used for characterization and mechanical properties exploration. The microstructure of the sintered alloy showed ordered and disordered BCC phases, as well as a minor FCC phase. The introduction of oxide reinforcements and microstructure refinement through mechanical alloying resulted in a change in phase quantification and grain structure, leading to increased hardness and elastic modulus in the consolidated samples.