Additive manufacturing of Al0.3CoCrFeNi high-entropy alloy by powder feeding laser melting deposition

Abstract

Al0.3CoCrFeNi high-entropy alloy (HEA) was additively manufactured by laser melting deposition (LMD) with emphasis on its microstructure and tensile properties. The LMD as-built HEA features a< 110 > fiber texture aligned toward the build direction. The dislocation loops are observed with a high density of dislocations neighboring to them in the LMDed samples. The partials dislocation glides induced by thermal stress leading to disordered-ordered transformation during LMD. Besides, the precipitated B2 particles are induced by thermal stress during cooling or thermal exposure during remelting. The cracks easily initiate and propagate along with the phase boundaries between the matrix FCC and precipitated B2 phases. Such cracks damage the tensile properties resulting in poor ductility in the tensile tests. Subsequent annealing facilitate the further precipitation of the B2 and σ phase, which introduces hardening and leading to the increase of the Vickers hardness and wear resistance of the annealed samples. Nevertheless, the annealing induces dislocation recovery, which reduces the required critical shearing stress for plastic deformation. As a consequence, the yield stress decreases from 476.9 ± 6.4–373.5 ± 6.8 MPa after annealing.