AUTHOR=Molina Veronica Rocio , Weisheit Andreas , Gein Sergej , Hecht Ulrike , Vogiatzief Dimitrios 

TITLE=Laser Metal Deposition of Ultra-Fine Duplex AlCrFe2Ni2-Based High-Entropy Alloy

JOURNAL=Frontiers in Materials

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2020.00275

DOI=10.3389/fmats.2020.00275

ISSN=2296-8016

ABSTRACT=<p>A duplex, nano-scale Co-free high-entropy alloy (HEA) based on AlCrFe<sub>2</sub>Ni<sub>2</sub> was processed using laser material deposition (LMD). Process parameters in various beam diameter configurations, as well as deposition strategies, were used while the alloy microstructure was investigated in the as-built and heat-treated condition. Interlayer regions present a duplex microstructure composed of ultra-fine face-centered cubic (FCC)-platelets nucleated in a nano-scale structured body-centered cubic (BCC) phase. Rapid cooling during LMD induces the decomposition of the BCC phase into ordered and disordered nano-scaled structures. The hard and brittle BCC phase yields a high crack susceptibility during rapid cooling in the LMD process. A suitable processing strategy paired with a post-processing heat treatment was developed to solve this challenge. After heat treatment at 900°C and 6 h annealing time with subsequent furnace cooling, the material presented a homogeneous duplex ultra-fine FCC/BCC microstructure and high bending strength (2310 MPa) compared to a heat-treated cast duplex-steel (1720 MPa) while maintaining excellent ductility (no failure at 20% bending strain).</p>