Additive Manufacturing Technologies of High Entropy Alloys (HEA): Review and Prospects

Abstract

Additive manufacturing (AM) technologies have gained considerable attention in recent years as an innovative method to produce high entropy alloy (HEA) components. The unique and excellent mechanical and environmental properties of HEAs can be used in various demanding applications, such as the aerospace and automotive industries. This review paper aims to inspect the status and prospects of research and development related to the production of HEAs by AM technologies. Several AM processes can be used to fabricate HEA components, mainly powder bed fusion (PBF), direct energy deposition (DED), material extrusion (ME), and binder jetting (BJ). PBF technologies, such as selective laser melting (SLM) and electron beam melting (EBM), have been widely used to produce HEA components with good dimensional accuracy and surface finish. DED techniques, such as blown powder deposition (BPD) and wire arc AM (WAAM), that have high deposition rates can be used to produce large, custom-made parts with relatively reduced surface finish quality. BJ and ME techniques can be used to produce green bodies that require subsequent sintering to obtain adequate density. The use of AM to produce HEA components provides the ability to make complex shapes and create composite materials with reinforced particles. However, the microstructure and mechanical properties of AM-produced HEAs can be significantly affected by the processing parameters and post-processing heat treatment, but overall, AM technology appears to be a promising approach for producing advanced HEA components with unique properties. This paper reviews the various technologies and associated aspects of AM for HEAs. The concluding remarks highlight the critical effect of the printing parameters in relation to the complex synthesis mechanism of HEA elements that is required to obtain adequate properties. In addition, the importance of using feedstock material in the form of mix elemental powder or wires rather than pre-alloyed substance is also emphasized in order that HEA components can be produced by AM processes at an affordable cost.

Fused Filament Fabrication for Metallic Materials: A Brief Review

“…HEAs also exhibit exceptional stability at elevated temperatures, making them ideal for thermal cycling applications or high operating temperatures. Furthermore, certain HEAs outperform traditional alloys in corrosive environments, ensuring durability and longevity in challenging conditions [10,[129][130][131]. HEAs are promising multi-component alloys with a unique combination of novel microstructures, and using FFF in AM will bring a new paradigm by offering unique properties and enabling new applications.…”

Composition Design Strategy for High Entropy Amorphous Alloys

“…Uporov et al found that ScGdTbDyHo HEA possesses good magnetocaloric properties and it can be influenced by the synthesis route [27]. Most HEAs were prepared by casting method; recently it was found that additive manufacturing characterized by net-shape processing is suitable for elevating the properties of HEAs [28][29][30]. Overall, great progress has been made in phase forming rules, composition design, processing, and application of HEA under various circumstances; they may be potential materials applied in many fields, such as heat-resistant and wear-resistant coatings, magnetic materials, and extreme high/low-temperature materials, etc.…”

Effects of Wire Electrical Discharge Finishing Cuts on the Surface Integrity of Additively Manufactured Ti6Al4V Alloy

“…The research conducted on the optimization of the SLM process [10][11][12][13] improved the properties of the manufactured parts; however, achieving a roughness below 1 micron, which is very often required in industrial applications, is still a challenge. Despite the many advantages of using SLM in the production of parts for the aerospace or power industry [14,15], the high surface roughness, dimensional and geometric inaccuracy [16,17], defects of surface layers such as balling effect [18,19], power adhesion [20], and microcracks [21,22] in many cases require the use of additional post-processing technologies [23]. The choice of finishing techniques such as machining [24][25][26], laser polishing [27,28], mechanical polishing [29], or abrasive flow machining [30,31] is quite challenging, and it depends on the geometry of the workpiece and the required surface integrity and dimensional accuracy.…”