Expanding particle size distribution and morphology of aluminium-silicon powders for Laser Beam Melting by dry coating with silica nanoparticles

Karg, Michael; Munk, Alexander; Ahuja, Bhrigu; Backer, Manuel Veit; Schmitt, Jana; Stengel, Christopher; Kuryntsev, S. V.; Schmidt, Michael

doi:10.1016/j.jmatprotec.2018.08.045

Cited by 24 publications

(19 citation statements)

References 17 publications

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“…They have mostly spherical to slightly ovoidal particle shapes. That indicates atomization with inert gas and little O absorption, which would cause spattered particles [ 46 , 79 ]. Increased O content impedes high ρ rel in LBM of Al alloys [ 8 , 36 ].…”

Section: Resultsmentioning

confidence: 99%

“…For all experiments, except establishment of the initial situation and some angle of repose measurements, Al powders are dry coated with 0.3 wt% SiO x fumed silica nanoparticles Aerosil ® R 106 by Evonik Industries AG (Essen, Germany). This is conducted by mixing in a Turbula ® T2A shaker (Willy A. Bachofen AG, Muttenz, Switzerland) on maximum speed for 1 h [ 46 , 63 ]. No ball milling and no mechanical alloying are performed.…”

Section: Methodsmentioning

confidence: 99%

“…With metal particles in the single-digit and double-digit micrometer scale, effects of particle mass can be pushed into the background by surface effects [ 43 ]. One consequence of this is reduced powder flowability, which can be compensated sufficiently to facilitate spreading in thin layers for LBM by dry coating with nanoparticles [ 36 , 44 , 45 , 46 ]. Dry coated nanoparticles act as spacers increasing the distance between microparticles and lowering van der Waals forces [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

“…The system of Al-Cu is chosen because of its challenging mass density ratio of 3.3, and because it attracts increasing scientific interest with regards to LBM [ 25 , 27 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ], since processability has been shown [ 61 , 62 ]. The range of free-flowing particle sizes is extended to particles < 20 µm by dry coating with SiO x nanoparticles [ 46 ]. Maximum particle size is limited to 63 µm, which is common for LBM.…”

Section: Introductionmentioning

confidence: 99%

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Laser Alloying Advantages by Dry Coating Metallic Powder Mixtures with SiOx Nanoparticles

et al. 2018

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Up to now, minimizing segregation of free-flowing, microscale metal powder mixtures driven by different mass density is an open challenge. In this work, effects of particle size variation on homogeneity of Al-Cu mixtures, with a density ratio of 3.3, are examined. Dry coating Al particles with 0.3 wt% fumed silica SiOx nanoparticles significantly decreases interparticle attraction. This enlarges the range of free-flowing Al particle sizes to < 20 µm. Powder mixture homogeneity is examined optically in vibrated bulk powder and thinly spread layers. From various powder mixtures, solid samples are built layer by layer with the Additive Manufacturing (3D printing) technology Laser Beam Melting in metal powder bed (LBM). Chemical homogeneity of solids is evaluated via energy-dispersive X-ray spectroscopy, backscattered electron microscopy, metallographic analysis and tensile tests. Persistent homogeneity of Al-Cu powder mixtures and LBM solids is found only with particles < 20 µm dry coated with SiOx nanoparticles. Observed segregation phenomena are explained with a decrease in particle mobility at increasing local concentration and the decreasing effectiveness of mass in smaller particles. The main effects are based on geometry, so they are expected to be transferrable to other nanoparticles, alloying components and powder bed technologies, e.g., binder jetting.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laser Alloying Advantages by Dry Coating Metallic Powder Mixtures with SiOx Nanoparticles

et al. 2018

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“…The proportion of the elements with a low boiling point is slightly reduced in the PBF-LB/M sample. To improve the flowability, which is especially necessary for the fine fraction due to its poor flow behavior, 0.3 wt.% Aerosil R106 particles were added similar to a protocol described in [35]. Subsequent dry-coating was carried out using a Turbula T2A shaker (Willy A. Bachofen AG, Muttenz, Switzerland) at a speed of 96 rpm and a mixing time of 1 h. Electron imaging has shown a homogeneous distribution of the SiO 2 particles on the powder surface (see Figure 5c).…”

Section: Used Parameter Setsmentioning

confidence: 99%

Grain Structure Evolution of Al–Cu Alloys in Powder Bed Fusion with Laser Beam for Excellent Mechanical Properties

Rasch¹,

Heberle

Dechet³

et al. 2019

Materials

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Powder Bed Fusion with Laser Beam of Metals (PBF-LB/M) is one of the fastest growing technology branches. More and more metallic alloys are being qualified, but processing of aluminum wrought alloys without cracks and defects is still challenging. It has already been shown that small parts with low residual porosity can be produced. However, suffering from microscopic hot cracks, the fracture behavior has been rather brittle. In this paper different combinations of temperature gradients and solidification rates are used to achieve specific solidification conditions in order to influence the resulting microstructure, as well as internal stresses. By this approach it could be shown that EN AW-2024, an aluminum-copper wrought alloy, is processable via PBF-LB/M fully dense and crack-free with outstanding material properties, exceeding those reported for commonly manufactured EN AW-2024 after T4 heat treatment.

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Recent Advances on High‐Entropy Alloys for 3D Printing

et al. 2020

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Boosted by the success of high-entropy alloys (HEAs) manufactured by conventional processes in various applications, the development of HEAs for three-dimensional (3D) printing has been advancing rapidly in recent years. 3D printing of HEAs gives rise to great potential for manufacturing geometrically complex HEA products with desirable performances, thereby inspiring their increased manifestation in industrial applications. In this paper, a comprehensive review of the recent achievements of 3D printing of HEAs is provided, in the aspects of their powder development, printing processes, microstructures, properties and potential applications. It begins with the introduction of the fundamentals of 3D printing and HEAs as well as the unique properties of 3D-printed HEA products. The processes for the development of HEA powders, including atomization and mechanical alloying, and the powder properties are then presented. Thereafter, typical processes for printing HEA products from powders, namely, directed energy deposition, selective laser 2 melting and electron beam melting, are discussed with regard to the phases, crystal features, mechanical properties, functionalities and potential applications of these products (particularly in the aerospace, energy, molding and tooling industries). Finally, perspectives are outlined to provide guidance for future research.

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Expanding particle size distribution and morphology of aluminium-silicon powders for Laser Beam Melting by dry coating with silica nanoparticles

Cited by 24 publications

References 17 publications

Laser Alloying Advantages by Dry Coating Metallic Powder Mixtures with SiOx Nanoparticles

Laser Alloying Advantages by Dry Coating Metallic Powder Mixtures with SiOx Nanoparticles

Grain Structure Evolution of Al–Cu Alloys in Powder Bed Fusion with Laser Beam for Excellent Mechanical Properties

Recent Advances on High‐Entropy Alloys for 3D Printing

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