Strengthening Mechanisms in Bulk FeCoCrNiAlx (x=0, 0.5, 1.0) High‐Entropy Alloys Fabricated by Laser Melting Deposition

Abstract

Herein, FeCoCrNiAl x (x = 0, 0.5, 1.0) high‐entropy alloys (HEAs) are fabricated by the laser melting deposition (LMD) technique. With the increase of Al content, the LMD‐ed microstructure transitions from a single face‐centered cubic (FCC) phase to a dual‐phase structure containing a small amount of body‐centered cubic (BCC) phase (5.3%), and the proportion of the final BCC phase increases significantly to 98.2%. In addition to the compression tests, four strengthening models are used to evaluate the theoretical strength of the three alloys. The addition of Al element as grain refiner can improve the ultimate compressive strength of HEAs; however, the yield strength and plasticity do not improve, as theoretically expected. The FCC phase with more slip systems leads to higher plasticity in the LMD‐ed FeCoCrNi HEA but results in lower yield strength. The LMD‐ed FeCoCrNiAl0.5 HEA exhibits the best combination of strength and plasticity. Therefore, to meet the required service requirements, the content of Al in the FeCoCrNiAl x HEA should be carefully controlled under the premise of considering the actual working conditions.