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https://doi.org/10.1007/s11837-019-03715-1  2019 The Minerals, Metals & Materials Society

PROGRESS IN HIGH-ENTROPY ALLOYS

Selective Laser Melting of Al0.3CoCrFeNi High-Entropy Alloy: Printability, Microstructure, and Mechanical Properties FLORIAN PEYROUZET,1,2 DORIAN HACHET,3 ROMAIN SOULAS,1 ´ PHANE GODET,3 CHRISTELLE NAVONE,1 STE 2,4 ´ and STEPHANE GORSSE 1.—LITEN, CEA, 38054 Grenoble, France. 2.—Univ. Bordeaux, CNRS, Bordeaux INP, ICMCB, UMR 5026, 33600 Pessac, France. 3.—Service 4MAT, Universite´ libre de Bruxelles, 1050 Brussels, Belgium. 4.—e-mail: [email protected]

Al0.3CoCrFeNi high-entropy alloy (HEA) was additively manufactured by powder-bed selective laser melting (SLM) with emphasis on its microstructure and tensile properties. Al0.3CoCrFeNi showed excellent printability, enabling fabrication of fully dense products. The microstructure of the SLM as-built HEA consisted of a single-phase disordered face-centered cubic solid solution with fine columnar grains elongated along the build direction. The characteristic features of the as-built microstructure were a fiber texture aligned toward the build direction and a large dislocation density. As a consequence, printed Al0.3CoCrFeNi HEA exhibited superior tensile strength in comparison with as-cast or wrought counterparts.

INTRODUCTION The high-entropy alloy (HEA)1,2 and complex concentrated alloy (CCA)3 concepts offer the designer new options for advanced materials with better structural properties.4–6 While the HEA approach focuses on a single disordered solid-solution phase, CCAs can exhibit multiphase microstructures and encompass HEAs. We do not distinguish between HEA and CCA herein, preferring to use the term HEA. Rather than using one principal element as an alloy base, HEAs/CCAs consist of a concentrated blend of at least three principal elements acting as one alloy ‘‘hybrid base.’’ This paradigm change has several important consequences7: (i) the 67 stable metallic elements give a total of over 110 million new alloy bases with three, four, five, or six principal elements, and (ii) the exploration of the composition space is shifted from the boundaries of multicomponent phase diagrams to the vast and uncharted central regions. So far, among the new alloy families that have emerged, the 3d transition metal (TM) family, which derivates from the Cantor alloy, i.e., CoCrFeMnNi face-centered-cubic (FCC) solid-solution phase, have attracted great attention because of their attractive mechanical performance. Indeed, 3d TM HEAs/CCAs can be regarded as an extension of

austenitic stainless steels, austenitic nickel alloys, and nickel-based superalloys. Whereas a great deal of work is currently underway on additive manufacturing of these three conventional alloy classes, three-dimensional (3D) printing of 3d TM HEAs/ CCAs has received much less attention.8–18 In this paper, we explore the microstructure and tensile properties of Al0.3CoCrFeNi HEA processed by powder-bed selective laser melting (SLM). Our alloy selection is motivated by the exc