Microstructure and hydrogen storage properties of a TiZrNbMoV high entropy alloy synthesized using Laser Engineered Net Shaping (LENS)

Kunce, Izabela; Polański, Marek; Bystrzycki, J.

doi:10.1016/j.ijhydene.2014.02.067

Cited by 211 publications

(101 citation statements)

References 19 publications

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“…Exploratory alloy discovery, design and development is a crucial aspect of materials research for the growth of industries such as aerospace [1], biomedical [2,3] and energy generation and storage [4]. Recently, this aspect of material research has expanded past that of the conventional alloy (consisting of 1 or 2 principle components) into a new class of highly alloyed materials, high-entropy alloys (HEAs).…”

Section: Introductionmentioning

confidence: 99%

Predicting the formation and stability of single phase high-entropy alloys

King

Middleburgh

McGregor³

et al. 2016

Acta Materialia

321

120

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Abstract:A method for rapidly predicting the formation and stability of undiscovered single phase high-entropy alloys (SPHEAs) is provided. Our software implementation of the algorithm uses data for 73 metallic elements and rapidly combines them -4, 5 or 6 elements at a time -using the Miedema semi-empirical methodology to yield estimates of formation enthalpy. Approximately 186,000,000 compositions of 4, 5 and 6 element alloys were screened, and ~1,900 new equimolar SPHEAs predicted. Of the 185 experimentally reported HEA systems currently known, the model correctly predicted the stability of the SPHEA structure in 177. The other sixteen were suggested to actually form a partially ordered solid solution -a finding supported by other recent experimental and theoretical work. The stability of each alloy at a specific temperature can also be predicted, allowing precipitation temperatures (and the likely precipitate) to be forecast. This combinatorial algorithm is described in detail, and its software implementation is freely accessible through a webservice allowing rapid advances in the design, development and discovery of new technologically important alloys. , and re-iterated by others since then [1,12], defines a HEA as any alloy consisting of 5 or more elements between 5 -35 at. %. As such, this type of HEA will usually possess a microstructure consisting of two or more distinct phases, some of which are likely to be brittle intermetallic compounds. Although, multiphase strengthening is sometimes desirable in alloys, a large amount of any brittle phase will generally make an alloy unusable as a structural material and such HEAs are therefore mundane. However, as will be discussed shortly, in a few special cases, the additional entropy of the multi-element composition will stabilise a microstructure consisting of either (i) a single solid solution having one of the simple close-packed crystal structures (FCC, HCP or BCC) or (ii) a duplex microstructure consisting of two such simple solid solutions. Generally, it is these non-trivial examples of HEA that interest investigators.This is because the resulting random solid solution(s) will exhibit a combination of ductility coupled with significant solid solution hardening. We recommend use of the term single 2 phase high-entropy alloy (SPHEA) as a more restrictive term to differentiate the rare and desirable single phase type of HEA from generic examples of multiphase HEAs.Combining Yeh's compositional limits [7] with the requirement for a single phase solid solution, we can define a SPHEA as an alloy with  4 alloying elements, at least 4 of which with a molar ratio between 0.33 -1 to that of the highest contributing element. These alloys must be able to display a single phase of simple, random, close-packed structure below the solidus.We return now to the factors that might stabilise a SPHEA. The prevailing hypotheses were (i) that the simple crystal structure or structures are thermodynamically stabilised, relative to possible intermetallic compounds, by the inc...

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Section: Introductionmentioning

confidence: 99%

Predicting the formation and stability of single phase high-entropy alloys

King

Middleburgh

McGregor³

et al. 2016

Acta Materialia

321

120

View full text Add to dashboard Cite

show abstract

“…11 Apart from bulk material consolidation methods such as casting and sintering, HEAs can also be deposited as a surface coating. Various techniques of welding, 9,12 thermal spraying, 13 selective laser melting, 14 direct laser deposition 8,[15][16][17][18] and additive manufacturing [19][20][21][22] are already reported in the literature as experimental methods to produce HEA coatings.…”

Section: Introductionmentioning

confidence: 99%

Additive Manufacturing of High-Entropy Alloys by Laser Processing

Ocelík

Janssen

Smith

et al. 2016

JOM

129

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This contribution concentrates on the possibilities of additive manufacturing of high-entropy clad layers by laser processing. In particular, the effects of the laser surface processing parameters on the microstructure and hardness of high-entropy alloys (HEAs) were examined. AlCoCrFeNi alloys with different amounts of aluminum prepared by arc melting were investigated and compared with the laser beam remelted HEAs with the same composition. Attempts to form HEAs coatings with a direct laser deposition from the mixture of elemental powders were made for AlCoCrFeNi and AlCrFeNiTa composition. A strong influence of solidification rate on the amounts of face-centered cubic and bodycentered cubic phase, their chemical composition, and spatial distribution was detected for two-phase AlCoCrFeNi HEAs. It is concluded that a high-power laser is a versatile tool to synthesize interesting HEAs with additive manufacturing processing. Critical issues are related to the rate of (re)solidification, the dilution with the substrate, powder efficiency during cladding, and differences in melting points of clad powders making additive manufacturing processing from a simple mixture of elemental powders a challenging approach.

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“…Therefore, it can be applied onto the surface of components in a variety of sizes and shapes, and it has a wide range of industrial applications. Furthermore, Kunce et al 29,30 recently used the direct laser-engineered net shaping (LENS) method to prepare a cylindrical ZrTiVCr FeNi high-entropy sample used as hydrogen storage materials, with a diameter of 15 mm and a height of 5-10 mm. The LENS method enables the direct production of high-performance metal components from metal powders plus 3D computer-aided design (CAD) models, and it has a significant advantage over conventional manufacturing methods in terms of tailoring the microstructure, shape, size, and internal architectures or porous structures, by controlling different process parameters.…”

Section: Laser-cladded High-entropy Alloy Coatingsmentioning

confidence: 99%

Application Prospects and Microstructural Features in Laser-Induced Rapidly Solidified High-Entropy Alloys

Zhang

et al. 2014

JOM

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Recently, high-entropy alloys (HEAs) have attracted much interest in the materials community, as they offer massive opportunities to observe new phenomena, explore new structure, and develop new materials. Particularly, it is attractive to prepare high-performance HEA coatings by laser-induced rapid solidification, which can be formed on the surface of components and parts in a variety of sizes and shapes with a lower cost in comparison with those bulk material fabrication methods. From the technical point of view, laser-induced rapid solidification could hamper the compositional segregation, improve the solubility in solid-solution phases, and lead to the strengthening effect by the grain refinement. This article reviews the recent work on the typical microstructural features and the mechanical and chemical properties in laser-induced rapidly solidified HEAs, and these data are compared with conventional Co-and Ni-based alloy coatings. The article concludes with suggestions for future research and development in HEAs, from considerations of their characteristic properties.

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Microstructure and hydrogen storage properties of a TiZrNbMoV high entropy alloy synthesized using Laser Engineered Net Shaping (LENS)

Cited by 211 publications

References 19 publications

Predicting the formation and stability of single phase high-entropy alloys

Predicting the formation and stability of single phase high-entropy alloys

Additive Manufacturing of High-Entropy Alloys by Laser Processing

Application Prospects and Microstructural Features in Laser-Induced Rapidly Solidified High-Entropy Alloys

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