Effect of Y$_2$O$_3$ addition on the microstructure and mechanical properties of an Al$_{1.8}$CoCrCu$_{0.5}$FeNi BCC HEA

• Published in: Journal of alloys and compounds 2023-10, Vol.960
• Main Authors: Reverte, Eduardo, Keller, Clément, Calvo-Dahlborg, Monique, Alcalá, Germán, Campos, Mónica, Cornide, Juan
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Engineering Sciences
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2023.170647

The present study investigated the influence of Y$_2$O$_3$ addition by mechanical alloying (MA) on the microstructure 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 Al$_{1.8}$CoCrCu$_{0.5}$FeNi 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 disordered 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 contributors to the increase in hardness and elastic modulus in the consolidated samples.