Positron annihilation studies on FeCrCoNi high entropy alloy

Abhaya, S.; Rajaraman, R.; Kalavathi, S.; Amarendra, G.

doi:10.1016/j.jallcom.2014.09.137

Cited by 33 publications

(19 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results were found to be in agreement with past experimental results, especially for systems with higher transition temperatures. For example, this method predicts that NbTaTiHfZr, NbHfTiZr and MoNbTaVW are stable above 1162 K, 1359 K and 1580 K, respectively, which aligns well with the results by Senkov et al [47], Wu et al [48] and Zou et al [49] who studied the homogenisation and structural stability during annealing of these alloys. However, difficulties in accurately identifying the temperature in which precipitates occur at low temperatures arise due to kinetic effects.…”

Section: Predicting Precipitation Temperaturessupporting

confidence: 86%

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

King

Middleburgh

McGregor³

et al. 2016

Acta Materialia

322

120

View full text Add to dashboard Cite

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...

show abstract

Section: Predicting Precipitation Temperaturessupporting

confidence: 86%

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

King

Middleburgh

McGregor³

et al. 2016

Acta Materialia

322

120

View full text Add to dashboard Cite

show abstract

“…It was furthermore found to decrease with annealing temperature due to a suggested defect recovery during heating. From the XRD measurements the authors concluded that the alloy was single phase and that it remained stable even after annealing 1h at 1100°C [33]. These results agree within experimental errors with the XRD results presented above.…”

Section: Effect Of Heat Treatments On the Structure Of Ccf Y Nsupporting

confidence: 83%

“…XRD and positron annihilation measurements on CCFN buttons produced by arc melting were reported [33]. The lattice constant was derived to 3.578 Å which is to be compared to 3.5720 Å obtained from the HEXRD measurements in the present study.…”

Section: Effect Of Heat Treatments On the Structure Of Ccf Y Nmentioning

confidence: 75%

See 1 more Smart Citation

Structure of some CoCrFeNi and CoCrFeNiPd multicomponent HEA alloys by diffraction techniques

Dahlborg

Cornide

Calvo-Dahlborg

et al. 2016

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…High entropy of random mixing of the principle elements can prevent the formation of ordered solid solutions and intermetallic phases. Thus, HEAs are mainly consisted of simple solid solution [22][23][24][25][26][27][28]. Because of a multi-component solid solution, HEAs possess high strength, good structural stability and exceptional high-temperature strength.…”

Section: A N U S C R I P Tmentioning

confidence: 99%