Microstructural Evolution of (Feconi)85.84al7.07ti7.09 High-Entropy Alloy Fabricated by an Optimized Selective Laser Melting Process

Abstract

High-entropy alloy (HEA) FeCoNiAlTi (FCNAT) systems have been demonstrated to provide high strength while sustaining good ductility, which is of particular interest for the fabrication of structural components with complex geometries. Moreover, unlike conventional fabrication methods, the layer-by-layer strategy applied in selective laser melting (SLM) technology can meet the high demand for fabricating highly complex structural components from HEAs. However, SLM fabrication technology has not yet been applied in conjunction with FCNAT-HEA systems, and the optimal SLM processing parameters and the microstructural characteristics of the resulting components remain unknown. The present study addresses this issue by fabricating highly dense (>99.9%) cubic (FeCoNi) 85.84 Al 7.09 Ti 7.07 FCNAT-HEA samples with dimensions of 10 mm × 10 mm × 10 mm. First, the optimal SLM process parameters and volumetric energy density are determined. Then, the unique layer-by-layer microstructure of the optimally fabricated samples, including grain growth orientations and grain boundary characteristics, are characterized in detail using a variety of imaging and spectroscopy methods, and variations in the chemical composition of the sample are evaluated.

Keywords: selective laser melting, high-entropy alloy, dislocation network structure, cellular structure, process parameter optimization