Microstructures, Oxidation, and Mechanical Properties of an FCC HEA

Abstract

Abstract Microstructures, oxidation, and mechanical properties of an FCC Al-Cu-Ni-Mn-Ag HEA have been investigated in this study. Three different microconstituents have been observed at room temperature. They consist of phases rich in (a) Ni, (b) Cu, and (c) Ag. Excellent oxidation resistance has been observed in a temperature range from 600 to 1000oC for 24 hours in air. Microconstituents rich in Cu and Ni provide favorable oxidation resistance while Al and Mn appear to be detrimental to the oxidation characteristics of this alloy. Microhardness has been determined for each microconstituent. Microconstituent rich in Ag has the highest hardness (429 HV) while Cu rich shows the lowest hardness of 392 HV. Comparatively, Ni and Ag rich microconstituents show the highest (447 HV) and lowest (112 HV) values, respectively, after oxidation at 1000oC for 24 hours in air. Grain sizes after oxidation have been observed to be controlled by the richness of the microconstituents. However, a reasonably good fit can be observed in a Hall-Petch plot using hardnesses and grain sizes observed of this study.