Laser-aided additive manufacturing of high entropy alloys: Processes, properties, and emerging applications

High entropy alloys (HEAs) are novel and futuristic materials, which possess extraordinary mechanical, physical, and chemical properties incomparable to traditional alloys. Nowadays, these alloys exhibit great potential for industrial applications due to the developments of ultra-superior HEAs. Due to the certain inherent limitations in the conventional processing routes of HEAs, the additive manufacturing (AM) of these alloys has been rapidly emerging in recent years. Laser-aided additive manufacturing (LAAM) of HEAs, through selective laser melting (SLM) and direct laser deposition (DLD), is expediting a renaissance in the material science field, with the prime focus on the fabrication of highly complex HEA parts with tailorable microstructures and mechanical properties. The review provides critical and in-depth details of laser-based technologies vastly applied for printing HEA products. Powder processing routes affect particle morphologies and the distribution of particle size. Additionally, the elemental composition of additively manufactured (AM-ed) HEAs plays an important role in the mechanical characteristics of 3D-printed parts. Furthermore, post-processing strategies help in mitigating residual stresses and other HEA defects. Compared to conventional manufacturing routes, HEAs printed through SLM and DLD technologies exhibited better mechanical characteristics due to rapid cooling rates. It is anticipated that AM-ed HEAs will be practically applied to manufacture large-scale and complex 3D industrial products, which will ultimately help in developing 3D-printed HEAs for industries.