Single-Bead Microstructures of an AlCrFeCoNi High Entropy Alloy Processed by the Laser Directed Energy Deposition

Abstract

This study investigated forming beads of an AlCrFeCoNi high entropy alloy (HEA) using the multi-beam laser directed energy deposition (L-DED). The X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) analyses confirmed the formation of a single phase composed of the AlCrFeCoNi HEA with the body-centered cubic (BCC) structure. Various laser powers (80W, 100W, and 120W) were examined to understand their effects on bead formation and bonding between the formed bead and substrate. At 80W, weak bonding was observed with a gap between the bead and substrate as the laser melted only the AlCrFeCoNi HEA powder. Increased laser power strengthened the bonding, but altered the HEA composition, deviating from the equiatomic compositions. Furthermore, the study revealed a correlation between laser power and grain size. With increasing laser power, microstructures with coarser grains were obtained.