Effects of process parameters on bead shape, microstructure, and mechanical properties in wire + arc additive manufacturing of Al0.1CoCrFeNi high-entropy alloy

Abstract

The goal of this study is to investigate the wire + arc additive manufacturing (WAAM) of a high-entropy alloy (HEA) and to identify the near-optimal process parameters. To achieve the goal, a two-stage investigation is attempted using pre-alloyed and extruded Al 0.1 CoCrFeNi wire. In the first stage, single-layer beads are deposited with a range of process parameters (current, wire feed speed, and travel speed). Through process-signal monitoring, bead cross-section measurements, and statistical analysis, the threshold of energy density (≥80 J/mm 3 ) for the uniform and continuous bead has been identified. In the second stage, thin-walled, multi-layer structures are deposited using two heat input conditions (low and high) with the same energy density. Large columnar grains with cellular dendritic substructures and a homogeneous composition are observed in both. Almost identical yield strength (260 MPa) and ultimate tensile strength (420 MPa) are measured with exceptional ductility (45–55%) for both deposits, which can be superior to casting and other AM processes. The high heat input is identified as the near-optimal processing condition, due to the improved surface quality, the higher ductility, and the higher deposition rate.