Formation and structure of V–Zr amorphous alloy thin films

King, D.J.M.; Middleburgh, Simon C.; Liu, Amelia C. Y.; Tahini, Hassan A.; Lumpkin, Gregory R.; Cortie, Michael B.

doi:10.1016/j.actamat.2014.10.016

Cited by 25 publications

(23 citation statements)

References 36 publications

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“…The pseudopotentials supplied in the VASP package, which use the projector augmented wave formalism, were used to investigate the amorphous structure. Each supercell was fully geometry optimised under constant pressure with a convergence stopping energy of 10 À3 eV per supercell (similar to calculations carried out previously [23,24,30]). A Methfessel-Paxton smearing method was used for all calculations with a tailored value of 0.125 eV.…”

Section: Methodsmentioning

confidence: 99%

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Structural stability and fission product behaviour in U3Si

Middleburgh

Burr

King

et al. 2015

Journal of Nuclear Materials

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Section: Methodsmentioning

confidence: 99%

“…Amorphous U 3 Si was investigated using a similar method to a recent article that investigated the V-Zr amorphous system [30]. 15 unique and randomly populated supercells (containing 108 atoms) were created and relaxed under constant pressure.…”

Section: Methodsmentioning

confidence: 99%

Structural stability and fission product behaviour in U3Si

Middleburgh

Burr

King

et al. 2015

Journal of Nuclear Materials

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“…A plane wave density functional theory (DFT) package, VASP [33,34], was used to calculate the ground state energies of the ordered and disordered AlCoFeNi HEA, the CoFe and AlNi binary intermetallic compounds, alloys in the Mo-Nb-Ti-V system, and a range of compounds in the Pt-Al system. The plane wave code was chosen as it is known to reproduce the intermetallic/metallic nature of the bonding to a satisfactory accuracy.…”

Section: First Principlesmentioning

confidence: 99%

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

King

Middleburgh

McGregor³

et al. 2016

Acta Materialia

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322

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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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“…The average size of dendritic arms is of the order of 10 µm. The mechanisms of phase segregation in the HEA and amorphous alloys have been investigated, using the approach of density-functional-theory modeling by Middleburgh et al [41,42]. Their results indicate that, for the CrCoFeNi HEA alloy, the vacancy-formation energies of Co, Fe, and Ni are positive, which is expected as a stable solid.…”

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confidence: 99%