Laser metal deposition of refractory high-entropy alloys for high-throughput synthesis and structure-property characterization

Dobbelstein, Henrik; George, E.P.; Gurevich, Evgeny L.; Kostka, Aleksander; Ostendorf, Andreas; Laplanche, Guillaume

doi:10.1088/2631-7990/abcca8

Cited by 41 publications

(19 citation statements)

References 62 publications

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“…The TiZrNbHfTa gradient HEAs were produced in Ref. [63] by the laser metal deposition (LMD) of elemental powder blends on a 3 mm-thick Ti substrate using a fiber laser (Manlight Gevel, Lannion, France) with a spot diameter of ~5 mm and a gaussian beam profile. The manufactured samples were annealed in the solid state which homogenized the dendritic microstructure of the deposited layers.…”

Section: Gb Wetting By Second Solid Phase In Primarily Inhomogeneous ...mentioning

confidence: 99%

Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review

et al. 2021

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In this review, the phenomenon of grain boundary (GB) wetting by the second solid phase is analyzed for the high entropy alloys (HEAs). Similar to the GB wetting by the liquid phase, the GB wetting by the second solid phase can be incomplete (partial) or complete. In the former case, the second solid phase forms in the GB of a matrix, the chain of (usually lenticular) precipitates with a certain non-zero contact angle. In the latter case, it forms in the GB continuous layers between matrix grains which completely separate the matrix crystallites. The GB wetting by the second solid phase can be observed in HEAs produced by all solidification-based technologies. The particle chains or continuous layers of a second solid phase form in GBs also without the mediation of a liquid phase, for example by solid-phase sintering or coatings deposition. To describe the GB wetting by the second solid phase, the new GB tie-lines should be considered in the two- or multiphase areas in the multicomponent phase diagrams for HEAs. The GB wetting by the second solid phase can be used to improve the properties of HEAs by applying the so-called grain boundary engineering methods.

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Section: Gb Wetting By Second Solid Phase In Primarily Inhomogeneous ...mentioning

confidence: 99%

Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review

et al. 2021

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“…Thus, the temperature interval where GB TJs are wetted is broader than that for GBs. Some indications of GB wetting by the second solid phase (such as the observed thick continuous GB layers) can also be found in numerous metallic HEAs such as Al 0.5 CoCuNiTi [9], TiZrNbHfTa [87,88], CrHfNbTaTi [10], TiNbTaZrMo [89], Mo 0.5 VNb TiCr x [27], Co 35 Cr 32 Ni 27 -Al 3 Ti 3 [17], AlCoCrFeNiTi 0.5 [90], CoCrFeMnNi [36], Co 35 Cr 25 Fe 40−x Ni x [91], TiNbTa 0.5 ZrAl 0.5 [92], and CoNiAlWTaTi [93].…”

Section: Grain Boundary Wetting Phenomenamentioning

confidence: 85%

Grain Boundary Wetting Phenomena in High Entropy Alloys Containing Nitrides, Carbides, Borides, Silicides, and Hydrogen: A Review

et al. 2021

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In this review, we analyze the structure of multicomponent alloys without principal components (they are also called high entropy alloys—HEAs), containing not only metals but also hydrogen, nitrogen, carbon, boron, or silicon. In particular, we discuss the phenomenon of grain boundary (GB) wetting by the melt or solid phase. The GB wetting can be complete or incomplete (partial). In the former case, the grains of the matrix are completely separated by the continuous layer of the second phase (solid or liquid). In the latter case of partial GB wetting, the second solid phase forms, between the matrix grains, a chain of (usually lenticular) precipitates or droplets with a non-zero value of the contact angle. To deal with the morphology of GBs, the new GB tie-lines are used, which can be constructed in the two- or multiphase areas of the multidimensional HEAs phase diagrams. The GBs in HEAs in the case of complete or partial wetting can also contain hydrides, nitrides, carbides, borides, or silicides. Thus, GB wetting by the hydrides, nitrides, carbides, borides, or silicides can be used in the so-called grain boundary chemical engineering in order to improve the properties of respective HEAs.

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“…To facilitate PBF-LB/M in the first place, it is mandatory that the powder mixture has sufficient flowability and can be recoated to thin layers [ 38 , 39 ], typically ranging between 20 µm and 100 µm for PBF-LB/M. Furthermore, a low oxygen content of the powders is considered beneficial for manufacturing refractory metal high entropy alloys [ 34 ]. Among other factors, the recoatability is determined by particle size and particle shape [ 38 ].…”

Section: Methodsmentioning

confidence: 99%

“…Laser processing of refractory metal high entropy alloys was first demonstrated by Dobbelstein et al, in 2016 [ 33 ] by means of directed energy deposition (DED) and in-situ alloy formation. Very comprehensive results of their work are also published in [ 34 ]. In contrast to conventional DED, Dobbelstein et al are not welding continuous weld seams but stack spot welds onto each other to form cylindrical samples, which limits the geometries that can be manufactured.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Alloy Formation of a WMoTaNbV Refractory Metal High Entropy Alloy by Laser Powder Bed Fusion (PBF-LB/M)

2021

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High entropy or multi principal element alloys are a promising and relatively young concept for designing alloys. The idea of creating alloys without a single main alloying element opens up a wide space for possible new alloy compositions. High entropy alloys based on refractory metals such as W, Mo, Ta or Nb are of interest for future high temperature applications e.g., in the aerospace or chemical industry. However, producing refractory metal high entropy alloys by conventional metallurgical methods remains challenging. For this reason, the feasibility of laser-based additive manufacturing of the refractory metal high entropy alloy W20Mo20Ta20Nb20V20 by laser powder bed fusion (PBF-LB/M) is investigated in the present work. In-situ alloy formation from mixtures of easily available elemental powders is employed to avoid an expensive atomization of pre-alloyed powder. It is shown that PBF-LB/M of W20Mo20Ta20Nb20V20 is in general possible and that a complete fusion of the powder mixture without a significant number of undissolved particles is achievable by in-situ alloy formation during PBF-LB/M when selecting favorable process parameter combinations. The relative density of the samples with a dimension of 6 × 6 × 6 mm3 reaches, in dependence of the PBF-LB/M parameter set, 99.8%. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) measurements confirm the presence of a single bcc-phase. Scanning electron microscopy (SEM) images show a dendritic and/or cellular microstructure that can, to some extent, be controlled by the PBF-LB/M parameters.

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Laser metal deposition of refractory high-entropy alloys for high-throughput synthesis and structure-property characterization

Cited by 41 publications

References 62 publications

Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review

Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review

Grain Boundary Wetting Phenomena in High Entropy Alloys Containing Nitrides, Carbides, Borides, Silicides, and Hydrogen: A Review

In-Situ Alloy Formation of a WMoTaNbV Refractory Metal High Entropy Alloy by Laser Powder Bed Fusion (PBF-LB/M)

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