Additive Manufacturing of High-Entropy Alloys: A Review

Chen, Shuying; Yang, Tong; Liaw, Peter K.

doi:10.3390/e20120937

Cited by 179 publications

(59 citation statements)

References 76 publications

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“…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][9][10][11][12][13][14][15][16][17][18] In this paper, we explore the microstructure and tensile properties of Al 0.3 CoCrFeNi HEA processed by powder-bed selective laser melting (SLM). Our alloy selection is motivated by the exceptional tunability principle of this FCC-based HEA, which has been demonstrated for wrought products; i.e., multiphase FCC-L1 2 , FCC-B2 or FCC-B2-r microstructures can be generated by tuning the cold rolling percentage and annealing temperature.…”

Section: Introductionmentioning

confidence: 99%

Selective Laser Melting of Al0.3CoCrFeNi High-Entropy Alloy: Printability, Microstructure, and Mechanical Properties

Peyrouzet

Hachet

Soulas

et al. 2019

JOM

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Al 0.3 CoCrFeNi high-entropy alloy (HEA) was additively manufactured by powder-bed selective laser melting (SLM) with emphasis on its microstructure and tensile properties. Al 0.3 CoCrFeNi 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 <110> fiber texture aligned toward the build direction and a large dislocation density. As a consequence, printed Al 0.3 CoCrFeNi HEA exhibited superior tensile strength in comparison with as-cast or wrought counterparts.

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Section: Introductionmentioning

confidence: 99%

Selective Laser Melting of Al0.3CoCrFeNi High-Entropy Alloy: Printability, Microstructure, and Mechanical Properties

Peyrouzet

Hachet

Soulas

et al. 2019

JOM

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“…It connects capillarity phenomena and entropy changes in the considered phase transition. Having in mind the outstanding rule of the entropy concepts in different related problems [35][36][37][38][39][40][41], such an approach can be considered already in advance as highly prospective. An extension of our method to ice-crystal nucleation in water will be presented in an accompanying paper [42].…”

Section: Introductionmentioning

confidence: 99%

Entropy and the Tolman Parameter in Nucleation Theory

Schmelzer

Abyzov

Байдаков

2019

Entropy

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Thermodynamic aspects of the theory of nucleation are commonly considered employing Gibbs’ theory of interfacial phenomena and its generalizations. Utilizing Gibbs’ theory, the bulk parameters of the critical clusters governing nucleation can be uniquely determined for any metastable state of the ambient phase. As a rule, they turn out in such treatment to be widely similar to the properties of the newly-evolving macroscopic phases. Consequently, the major tool to resolve problems concerning the accuracy of theoretical predictions of nucleation rates and related characteristics of the nucleation process consists of an approach with the introduction of the size or curvature dependence of the surface tension. In the description of crystallization, this quantity has been expressed frequently via changes of entropy (or enthalpy) in crystallization, i.e., via the latent heat of melting or crystallization. Such a correlation between the capillarity phenomena and entropy changes was originally advanced by Stefan considering condensation and evaporation. It is known in the application to crystal nucleation as the Skapski–Turnbull relation. This relation, by mentioned reasons more correctly denoted as the Stefan–Skapski–Turnbull rule, was expanded by some of us quite recently to the description of the surface tension not only for phase equilibrium at planar interfaces, but to the description of the surface tension of critical clusters and its size or curvature dependence. This dependence is frequently expressed by a relation derived by Tolman. As shown by us, the Tolman equation can be employed for the description of the surface tension not only for condensation and boiling in one-component systems caused by variations of pressure (analyzed by Gibbs and Tolman), but generally also for phase formation caused by variations of temperature. Beyond this particular application, it can be utilized for multi-component systems provided the composition of the ambient phase is kept constant and variations of either pressure or temperature do not result in variations of the composition of the critical clusters. The latter requirement is one of the basic assumptions of classical nucleation theory. For this reason, it is only natural to use it also for the specification of the size dependence of the surface tension. Our method, relying on the Stefan–Skapski–Turnbull rule, allows one to determine the dependence of the surface tension on pressure and temperature or, alternatively, the Tolman parameter in his equation. In the present paper, we expand this approach and compare it with alternative methods of the description of the size-dependence of the surface tension and, as far as it is possible to use the Tolman equation, of the specification of the Tolman parameter. Applying these ideas to condensation and boiling, we derive a relation for the curvature dependence of the surface tension covering the whole range of metastable initial states from the binodal curve to the spinodal curve.

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“…Pham et al reported extraordinary high yield strength of 520 MPa and elongation of ~60% in PBF AM SS 316 L (double of annealed commercial SS 316 L alloys) and highlighted fine subgrains having high dislocation density and strong twinning-induced plasticity 28 . Recently AM reaches HEAs, for example, AM CrCoNiFe (Al, Ti, Mn) [31][32][33] and AM refractory HEAs (MoNbTaW, TiZrNbTa) 34,35 . Noticeably, Li et al showed tensile strength over 600 MPa in a high energy laser AM CrCoNiFeMn HEA (not less than cast-wrought CrCoNiFeMn HEA) having a large number of dislocation pile-ups and nanotwins in refined grains 33 .…”

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confidence: 99%

Stacking Fault Energy Analyses of Additively Manufactured Stainless Steel 316L and CrCoNi Medium Entropy Alloy Using In Situ Neutron Diffraction

Woo

Jeong

Kim

et al. 2020

Sci Rep

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Stacking fault energies (SFE) were determined in additively manufactured (AM) stainless steel (SS 316 L) and equiatomic CrCoNi medium-entropy alloys. AM specimens were fabricated via directed energy deposition and tensile loaded at room temperature. In situ neutron diffraction was performed to obtain a number of faulting-embedded diffraction peaks simultaneously from a set of (hkl) grains during deformation. The peak profiles diffracted from imperfect crystal structures were analyzed to correlate stacking fault probabilities and mean-square lattice strains to the SFE. The result shows that averaged SFEs are 32.8 mJ/m 2 for the AM SS 316 L and 15.1 mJ/m 2 for the AM crconi alloys. Meanwhile, during deformation, the SFE varies from 46 to 21 mJ/m 2 (AM SS 316 L) and 24 to 11 mJ/m 2 (AM crconi) from initial to stabilized stages, respectively. The transient SFEs are attributed to the deformation activity changes from dislocation slip to twinning as straining. The twinning deformation substructure and atomic stacking faults were confirmed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The significant variance of the SFE suggests the critical twinning stress as 830 ± 25 MPa for the AM SS 316 L and 790 ± 40 MPa for AM CrCoNi, respectively.Excellent combination of strength, ductility, and toughness has been found in an equiatomic, face-centered-cubic CrCoNiFeMn high-entropy alloys (HEA) 1 . The reason of the exceptional properties at cryogenic temperature has been mainly attributed to the evolution of the nanoscale twinning under plastic deformation, so-called twinning-induced plasticity 2,3 . Compared to the HEA, superior mechanical properties of CrCoNi medium-entropy alloys (MEA) have been recently reported at both room and cryogenic temperature 4-13 . High attention has been focused on the evolution of the twinning substructure and/or a new phase with hexagonal close packed structure instead of the initial deformation mode of the dislocation slip in MEAs 6-9 . Systematic examinations of the substructure elucidate that the critical twinning stress of 790 ± 100 MPa reaches at the earlier strain of 9.7-12.9% for CrCoNi MEA than 720 ± 30 MPa at ~25% for CrCoNiFeMn HEA because of higher yield strength and work hardening rate with larger shear modulus of the MEA 8-10 . Earlier formation of the nano-twinning and its activation over a more extended strain range is of importance accepted as the reason of the exceptional strength-ductility-toughness combination in MEA.Stacking fault energy (SFE) has been accepted as a responsible parameter to determine the deformation schemes, which is typically by slip (>45 mJ/m 2 ) to twinning (20-45 mJ/m 2 ) and/or phase transformation (<20 mJ/m 2 ) as often reported in austenitic stainless steels [14][15][16][17][18][19][20][21] . The SFE is defined as the energy per fault area by www.nature.com/scientificreports www.nature.com/scientificreports/ SFE ranges 11-24 mJ/m 2 , b p is the magnitude of the Burgers vector of partials (0.146 nm), G is the shear...

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Additive Manufacturing of High-Entropy Alloys: A Review

Cited by 179 publications

References 76 publications

Selective Laser Melting of Al0.3CoCrFeNi High-Entropy Alloy: Printability, Microstructure, and Mechanical Properties

Selective Laser Melting of Al0.3CoCrFeNi High-Entropy Alloy: Printability, Microstructure, and Mechanical Properties

Entropy and the Tolman Parameter in Nucleation Theory

Stacking Fault Energy Analyses of Additively Manufactured Stainless Steel 316L and CrCoNi Medium Entropy Alloy Using In Situ Neutron Diffraction

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