Effects of mechanical activation on chemical homogeneity and contamination level in dual-phase AlCoCrFeNi high entropy alloy

AlCoCrFeNi High Entropy Alloys were here synthesized by the combination of Planetary Ball Milling and Spark Plasma Sintering at 1100 °C. The relatively low rotating speed led to a peculiar agglomerate state referred as “Mechanical Activated”. reactive sintering activated agglomerates leads unique dualphase microstructure: sintered sample exhibited distinctive nanostructured lamellar microstructure consisting two main phases (FCC BCC). Atom Probe Tomography (APT) was used ensure that chemically homogeneous nanoscale in each phase. APT also revealed presence Cr-rich sigma phase oxide nanoprecipitates. X-ray Photoelectron Spectrometry (XPS) results demonstrated most oxygen originated from commercial powders. Calphad calculations oxides could alter modifying global chemical composition.