Additive manufacturing of high-entropy alloys by thermophysical calculations and in situ alloying

Cagirici, Mehmet; Wang, Pan; Ng, Fern Lan; Nai, Mui Ling Sharon; Ding, Jun; Wei, Jun

doi:10.1016/j.jmst.2021.03.038

Cited by 43 publications

(5 citation statements)

References 62 publications

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“…For example, Sui et al (2021) added just 0.9 Wt.% Ni to Ti-6Al-4V to refine the microstructure and improve the mechanical properties in a directed energy deposition. Cagirici et al (2021) increased the Vicker hardness of a high entropy alloy five-fold by adding 0.5% Ti to the powder before electron beam melting, and Zhang et al (2019) showed great improvements in Inconel 718 properties with just 0.5% Al additions.…”

Section: Introductionmentioning

confidence: 99%

Impact of zirconia slurry in steel powder on melt pool characteristics in laser powder bed fusion

Davis

Nelson

Crane

2022

RPJ

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Purpose dding dopants to a powder bed could be a cost-effective method for spatially varying the material properties in laser powder bed fusion (LPBF) or for evaluating new materials and processing relationships. However, these additions may impact the selection of processing parameters. Furthermore, these impacts may be different when depositing nanoparticles into the powder bed than when the same composition is incorporated into the powder particles as by ball milling of powders or mixing similarly sized powders. This study aims to measure the changes in the single bead characteristics with laser power, laser scan speed, laser spot size and quantity of zirconia nanoparticle dopant added to SS 316 L powder. Design/methodology/approach A zirconia slurry was inkjet-printed into a single layer of 316 SS powder and dried. Single bead experiments were conducted on the composite powder. The line type (continuous vs balling) and the melt pool geometry were compared at various levels of zirconia doping. Findings The balling regime expands dramatically with the zirconia dopant to both higher and lower energy density values indicating the presence of multiple physical mechanisms that influence the resulting melt track morphology. However, the energy density required for continuous tracks was not impacted as significantly by zirconia addition. These results suggest that the addition of dopants may alter the process parameter ranges suitable for the fabrication of high-quality parts. Originality/value This work provides new insight into the potential impact of material doping on the ranges of energy density values that form continuous lines in single bead tests. It also illustrates a potential method for spatially varying material composition for process development or even part optimization in powder bed fusion without producing a mixed powder that cannot be recycled.

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Section: Introductionmentioning

confidence: 99%

Impact of zirconia slurry in steel powder on melt pool characteristics in laser powder bed fusion

Davis

Nelson

Crane

2022

RPJ

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“…The CoCrFeMnNi alloy was manufactured via SLM by alloying the Mn in-situ, and this resulted in the vaporisation of some of the Mn, and a reduction of Mn in some areas [15]. Cagirici et al also recently added Ti to the pre-alloyed CoCrFeMnNi and used Scanning Electron Beam Melting (SEBM) for in-situ alloying, resulting in a homogeneous distribution of Ti, as well as the appearance of surface cracks and brittle phases as the Ti concentration was increased [16]. In-situ alloying of elemental powders alone has also been used to manufacture refractory HEAs with some vaporisation of the lower melting point elements [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

In-Situ Alloying of CoCrFeNiX High Entropy Alloys by Selective Laser Melting

Farquhar

Maddison

Hardwick

et al. 2022

Metals

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High Entropy Alloys are a class of alloys which have been shown to largely exhibit stable microstructures, as well as frequently good mechanical properties, particularly when manufactured by additive manufacturing. Due to the large number of potential compositions that their multi-component nature introduces, high throughput alloy development methods are desirable to speed up the investigation of novel alloys. Here, we explore once such method, in-situ alloying during Additive Manufacture, where a powder of a certain pre-alloyed composition is mixed with the required composition of powder of an additional element, such that alloying takes place when powders are melted during the process. To test the effectiveness and capability of the approach, selective laser melting has been used to manufacture pre-alloyed CoCrFeNi, and also CoCrFeNiCu and CoCrFeNiTi alloys by combining pre-alloyed CoCrFeNi powder with elemental powders of Cu and Ti. Processing parameter variations are used to find the highest relative density for each alloy, and samples were then characterised for microstructure and phase composition. The CoCrFeNi alloy shows a single phase face centred cubic (FCC) microstructure, as found with other processing methods. The CoCrFeNiCu alloy has a two phase FCC microstructure with clear partitioning of the Cu, while the CoCrFeNiTi alloy has an FCC matrix phase with NiTi intermetallics and a hexagonal close packed (HCP) phase, as well as unmelted Ti particles. The microstructures therefore differ from those observed in the same alloys manufactured by other methods, mainly due to the presence of areas with higher concentrations than usually encountered of Cu and Ti respectively. Successful in-situ alloying in this process seems to be improved by the added elemental powder having a lower melting point than the base alloy, as well as a low inherent tendency to segregate. While not producing directly comparable microstructures however, the approach does seem to offer advantages for the rapid screening of alloys for AM processability, identifying, for example, extensive solid-state cracking in the CoCrFeNiTi alloy.

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“…Several materials have been used and failed until recent years, with the emergence of highentropy alloys and their characteristic features attracting research interest because of their high-entropy mixing and lattice distortion effect which gives the alloy strength preventing plastic deformation and dislocation movements [3][4][5]. Consequently, in the AlCo-CrCuFeNi high-entropy alloy composition, there must be at least five elements between 5 and 35 at.% in nearequal or equimolar concentrations enabling the alloy to form structural stability and solid solution FCC, BCC or FCC + BCC structures attributed to the valence electron concentration (VEC) [6][7][8], small atomic radius difference δ and large enthalpy of mixing H mix , [9,10].…”

Section: Introductionmentioning

confidence: 99%

Wear characteristics of laser-deposited AlCoCrCuFeNi high entropy alloy with finite element analysis

Dada

Popoola

Mathe

et al. 2022

Beni-Suef Univ J Basic Appl Sci

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Background Wear is a destructive phenomenon and one of the principal causes of material failure in moving components during surface interaction while in service. AlCoCrCuFeNi high-entropy alloy with its many properties is a potential material for aero-engine applications attributed to its outstanding relatively lightweight, high strength, good thermal, oxidation, and corrosion resistance properties. Hence, the investigation into the tribological behaviour of AlCoCrCuFeNi high-entropy alloys is essential to reduce maintenance costs and prolong the service life of this advanced material for aerospace applications. Most AlCoCrCuFeNi high-entropy alloy compositions were fabricated via arc melting, which has been reported to have defects attributed to slow solidification, consequently reducing the mechanical properties of the alloy with limited reports on other fabrication methods. Therefore, there is a need for the use of advanced manufacturing techniques for fabricating these alloys to improve the tribological properties. In this study, AlCoCrCuFeNi high-entropy alloy was fabricated via laser metal deposition. The influence of the laser processing parameters, rapid solidification, and the applied load on the tribological properties of the as-built alloys under dry conditions has been studied for aerospace applications. The counter ball rolling friction analysis was also investigated using COMSOL Multiphysics. Results The results showed that at a high laser power of 1600 W and a scan speed of 12 mm/s, the lowest wear rates and highest hardness values were observed. The average coefficient of friction at room temperature was 0.1 and 0.3 at a speed of 21 m/s. The dominant wear mechanism at room temperature was abrasive wear as the wear rate increased linearly with an increase in load from 10 to 20 N. The scan speed had the most significant influence on the wear behaviour of the as-built high-entropy alloy attributed to the rapid rate of solidification which occurs at higher scan speeds. Conclusions The study examines the wear characteristics of high-entropy alloys fabricated via laser deposition technique in comparison with those fabricated via conventional routes. Although there were similarities in the phase structures of both techniques, the results showed that the wear resistance of the laser-deposited high-entropy alloy was comparatively higher than the same alloy prepared via conventional methods. Laser additive manufacturing was concluded to be a more successful method in fabricating high-entropy alloys.

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Additive manufacturing of high-entropy alloys by thermophysical calculations and in situ alloying

Cited by 43 publications

References 62 publications

Impact of zirconia slurry in steel powder on melt pool characteristics in laser powder bed fusion

Impact of zirconia slurry in steel powder on melt pool characteristics in laser powder bed fusion

In-Situ Alloying of CoCrFeNiX High Entropy Alloys by Selective Laser Melting

Wear characteristics of laser-deposited AlCoCrCuFeNi high entropy alloy with finite element analysis

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