Processing of High-Entropy AlCoCr0.75Cu0.5FeNi Alloy by Spray Forming

Srivastava, V. C.; Mandal, G. K.; Ciftci, Nevaf; Uhlenwinkel, Volker; Mädler, Lutz

doi:10.1007/s11665-017-3071-2

Cited by 10 publications

(7 citation statements)

References 39 publications

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“…HEA powder particles were obtained as byproduct of a spray forming technique while investigating the influence of cooling rate on the microstructural evolution in the HEA with a nominal composition of AlCoCr 0.75 Cu 0.5 FeNi [21]. The spray forming setup was composed of an induction melting chamber, a tundish, and a free fall atomizer.…”

Section: Methodsmentioning

confidence: 99%

“…Fe --1 FIGURES Fig. 1: The schematic design of the spray atomization chamber as introduced in [22] (a) and measured X-ray diffractogram (B2 phase reflections highlighted) for the powder used, along with a reference of the same powder analyzed in [21] (b). Surface topography of the fabricated powder particles and location of TEM lamella extraction (c) along with an ion channeling contrast image of the metallographically prepared particle cross-sections, embedded in a conductive carbon-based matrix (d).…”

Section: Tablesmentioning

confidence: 99%

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Early stage phase separation of AlCoCr0.75Cu0.5FeNi high-entropy powder at the nanoscale

Peter

Duarte

Liebscher

et al. 2020

Journal of Alloys and Compounds

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High entropy alloys are generally considered to be single phase material. This state is, however, typically a non-equilibrium state after fabrication at high cooling rates. Phase constitution after fabrication or heat treatment is mostly known for isothermal annealing only and for casts as well as rapidly quenched alloys. Knowledge on early phase separation stages of high entropy alloys and their mechanisms are missing so far. Here, we present results on phase separation at intermediate cooling rates, by characterization of gas atomized powder of the AlCoCr 0.75 Cu 0.5 FeNi alloy. Although investigation by X-ray diffraction and Electron Backscatter Diffraction indicates a single-phase nature of the powder particles, aberrationcorrected scanning transmission electron microscopy and atom probe tomography reveal a nanoscale phase separation into Ni-Al-rich B2 and Fe-Cr-rich A2 regions as well as a high number density of 3.1x10 24 Cu-rich clusters per m 3 in the B2 matrix. The observed phase separation and cluster formation are linked to spinodal decomposition and nucleation processes, respectively. The study highlights that adequate characterization techniques need to be chosen when making statements about phase stability and structural evolution in compositionally complex alloys.

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Section: Methodsmentioning

confidence: 99%

Section: Tablesmentioning

confidence: 99%

Early stage phase separation of AlCoCr0.75Cu0.5FeNi high-entropy powder at the nanoscale

Peter

Duarte

Liebscher

et al. 2020

Journal of Alloys and Compounds

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“…These results are consistent with the observations characterized by the scanning transmission electron microscopy and atom probe tomography in [ 30 ]. It is worth mentioning that in both the previous XRD analyses on the same raw powder in [ 30 , 34 ], only one type of BCC phase was revealed. This is likely to result from the program settings of XRD measurement, e.g., the step size and count time per step, which are not efficient enough to depict the differences of structures.…”

Section: Resultsmentioning

confidence: 99%

“…The powder AlCoCr 0.75 Cu 0.5 FeNi was atomized with nitrogen using a free-fall atomizer in a spray forming process (ID number Sk2-800, more details as reported in [ 30 , 34 ]). Compared to equimolar AlCoCrCuFeNi alloy, the content of Cu is reduced in order to avoid segregation caused by its positive mixing enthalpy with each element of Cr, Co, Ni, and Fe [ 12 ].…”

Section: Methodsmentioning

confidence: 99%

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Microstructure and Properties of Additively Manufactured AlCoCr0.75Cu0.5FeNi Multicomponent Alloy: Controlling Magnetic Properties by Laser Powder Bed Fusion via Spinodal Decomposition

et al. 2022

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A non-equiatomic AlCoCr0.75Cu0.5FeNi alloy has been identified as a potential high strength alloy, whose microstructure and consequently properties can be widely varied. In this research, the phase structure, hardness, and magnetic properties of AlCoCr0.75Cu0.5FeNi alloy fabricated by laser powder bed fusion (LPBF) are investigated. The results demonstrate that laser power, scanning speed, and volumetric energy density (VED) contribute to different aspects in the formation of microstructure thus introducing alterations in the properties. Despite the different input parameters studied, all the as-built specimens exhibit the body-centered cubic (BCC) phase structure, with the homogeneous elemental distribution at the micron scale. A microhardness of up to 604.6 ± 6.8 HV0.05 is achieved owing to the rapidly solidified microstructure. Soft magnetic behavior is determined in all as-printed samples. The saturation magnetization (Ms) is dependent on the degree of spinodal decomposition, i.e., the higher degree of decomposition into A2 and B2 structure results in a larger Ms. The results introduce the possibility to control the degree of spinodal decomposition and thus the degree of magnetization by altering the input parameters of the LPBF process. The disclosed application potentiality of LPBF could benefit the development of new functional materials.

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