On Sluggish Diffusion in Fcc Al–Co–Cr–Fe–Ni High-Entropy Alloys: An Experimental and Numerical Study

Li, Qin; Chen, Weimin; Zhong, Jue; Zhang, Lijun; Chen, Qing; Liu, Zhe

doi:10.3390/met8010016

Cited by 61 publications

(30 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The comparison unambiguously substantiate that, at least, one has to use the results of the numerical inverse methods with a care. While the following ratio of the tracer diffusion coefficients is established by the direct method, D * Ni < D * Co < D * Fe < D * Cr [22,24], just opposite trends were found using the numerical inverse method in the work [31], see Fig. 6.…”

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 89%

“…the determination of the tracer diffusion coefficients from the known composition profiles and the corresponding thermodynamics -was not proven so far. Nevertheless, as it was mentioned, many efforts were put in the development of numerical procedures which ideally have to allow a direct solution of the inverse diffusion problem providing the concentration-dependent tracer diffusion coefficients from the known chemical profiles and the available thermodynamic assessment of the system [31]. According to the authors of the approach, the method was successfully applied to several binary, ternary and multi-component systems [31].…”

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 99%

“…Nevertheless, as it was mentioned, many efforts were put in the development of numerical procedures which ideally have to allow a direct solution of the inverse diffusion problem providing the concentration-dependent tracer diffusion coefficients from the known chemical profiles and the available thermodynamic assessment of the system [31]. According to the authors of the approach, the method was successfully applied to several binary, ternary and multi-component systems [31]. However, the authors have not provided a strict proof of the existence of a unique and stable solution of the inverse diffusion problem.…”

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 99%

“…The authors [31] consider the inverse method as a kind of numerical fitting of the interdiffusion profiles. Note that even a well established tracer method, see below, does not measure the underlying diffusion coefficient of a given chemical element in the compound.…”

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 99%

“…Tracer diffusion coefficients directly measured using the radiotracer technique by Vaidya et al[22,24] (solid lines) and determined by the numerical inverse method by Li et al[31] (dashed lines).…”

mentioning

confidence: 99%

See 4 more Smart Citations

A Mystery of "Sluggish Diffusion" in High-Entropy Alloys: The Truth or a Myth?

Divinski

Покоев

Esakkiraja

et al. 2018

View full text Add to dashboard Cite

High entropy alloys (HEAs) are considered as a novel class of materials with a large number of components (five and more) available in equiatomic or nearly equatomic proportions.One of the characteristic properties of HEAs was believed to be so-called 'sluggish' diffusion that should be crucial for intended high-temperature technological applications. The faith on this myth instead of rigorous experimental analysis played such a dominant role that the first set of data on interdiffusion, in fact based on an improper analysis, were cited in hundreds of articles to state the presence of sluggishness of diffusion rates in high entropy alloys.In this review, the recent data on atomic diffusion in HEAs are presented and critically discussed. The discussion is focused on tracer diffusion which is already measured dominantly for polycrystalline, but in some cases for single crystalline high-entropy alloys. The radiotracer technique provided a unique access to the diffusion rates of elements in the alloys and in fortunate cases these transport quantities could be measured in a single experiment, as in the case of Co, Cr, Fe and Mn diffusion in the CoCrFeMnNi HEA.Alternatively, a rigorous analysis of the interdiffuson experiments, which provide the diffusion rates of chemical species, too, becomes more and more sophisticated for three and more elements in an alloy and it is challenging to derive physically sound quantities from a general multicomponent diffusion experiment. Most promising in this case is the diffusion couple technique, especially the so-called pseudo-binary approach. This approach is analyzed with a focus on the applicability and the possible errors induced if up-hill diffusion appears.In the overview, it is shown that atomic diffusion in HEAs cannot a priori be considered as sluggish and both atomic interactions as well as correlation effects are responsible for the observed trends. Even if estimated on the same homologous scale, the diffusion retardation induced by a 'high entropy' in FCC crystals is not simply proportional to the number of alloying components and it is shown to be similar to that induced by, e.g., the L1 2 ordering in a binary system. Furthermore, the importance of cross-correlations in diffusion of different species in HEAs is highlighted. * Since there is no consensus about the way to list the principal elements in HEAs (alphabetic order, periodic table order, atomic percentage, etc), we will use the simple alphabetic order, as e.g. CoCrFeMnNi for the Cantor system.

show abstract

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 89%

Section: Inverse Solutions Of Interdiffusion Problemmentioning

confidence: 99%