Reply to comments on "Sluggish diffusion in Co-Cr-Fe-Mn-Ni high-entropy alloys" by K.Y. Tsai, M.H. Tsai and J.W. Yeh, Acta Materialia 61 (2013) 4887-4897

2017 ◽  
Vol 135 ◽  
pp. 158-159 ◽  
Author(s):  
Kun-Yo Tsai ◽  
Ming-Hung Tsai ◽  
Jien-Wei Yeh
Keyword(s):  
High Entropy Alloys ◽  
High Entropy ◽  
Sluggish Diffusion

scholarly journals High-Entropy Alloys for Advanced Nuclear Applications

Entropy ◽  
2021 ◽  
Vol 23 (1) ◽  
pp. 98
Author(s):  
Ed J. Pickering ◽  
Alexander W. Carruthers ◽  
Paul J. Barron ◽  
Simon C. Middleburgh ◽  
David E.J. Armstrong ◽  
...  
Keyword(s):  
Austenitic Steels ◽  
Irradiation Damage ◽  
High Entropy Alloys ◽  
Damage Resistance ◽  
High Entropy ◽  
Engineering Alloys ◽  
Sluggish Diffusion ◽  
Work Done ◽  
Current Engineering ◽  
Nuclear Applications

The expanded compositional freedom afforded by high-entropy alloys (HEAs) represents a unique opportunity for the design of alloys for advanced nuclear applications, in particular for applications where current engineering alloys fall short. This review assesses the work done to date in the field of HEAs for nuclear applications, provides critical insight into the conclusions drawn, and highlights possibilities and challenges for future study. It is found that our understanding of the irradiation responses of HEAs remains in its infancy, and much work is needed in order for our knowledge of any single HEA system to match our understanding of conventional alloys such as austenitic steels. A number of studies have suggested that HEAs possess `special’ irradiation damage resistance, although some of the proposed mechanisms, such as those based on sluggish diffusion and lattice distortion, remain somewhat unconvincing (certainly in terms of being universally applicable to all HEAs). Nevertheless, there may be some mechanisms and effects that are uniquely different in HEAs when compared to more conventional alloys, such as the effect that their poor thermal conductivities have on the displacement cascade. Furthermore, the opportunity to tune the compositions of HEAs over a large range to optimise particular irradiation responses could be very powerful, even if the design process remains challenging.

scholarly journals Al, Cu and Zr Addition to High Entropy Alloys: The Effect on Recrystallization Temperature

2018 ◽  
Vol 941 ◽  
pp. 1137-1142
Author(s):  
Elena Colombini ◽  
Andrea Garzoni ◽  
Roberto Giovanardi ◽  
Paolo Veronesi ◽  
Angelo Casagrande
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Single Phase ◽  
Boundary Energy ◽  
Cold Deformation ◽  
Recrystallization Temperature ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Ni Alloy ◽  
Sluggish Diffusion

The equimolar Cr, Mn, Fe, Co and Ni alloy, first produced in 2004, was unexpectedly found to be single-phase. Consequently, a new concept of materials was developed: high entropy alloys (HEA) forming a single solid-solution with a near equiatomic composition of the constituting elements. In this study, an equimolar CoCrFeMnNi HEA was modified by the addition of 5 at% of either Al, Cu or Zr. The cold-rolled alloys were annealed for 30 minutes at high temperature to investigate the recrystallization kinetics. The evolution of the grain boundary and the grain size were investigated, from the as-cast to the recrystallized state. Results show that the recrystallized single phase FCC structures exhibits different twin grains density, grain size and recrystallization temperatures as a function of the at.% of modifier alloying elements added. In comparison to the equimolar CoCrFeMnNi, the addition of modifier elements increases significantly the recrystallization temperature after cold deformation. The sluggish diffusion (typical of HEA alloys), the presence of a solute in solid solution as well as the low twin boundary energy are responsible for the lower driving force for recrystallization.

Sluggish diffusion in Co–Cr–Fe–Mn–Ni high-entropy alloys

2013 ◽  
Vol 61 (13) ◽  
pp. 4887-4897 ◽  
Author(s):  
K.-Y. Tsai ◽  
M.-H. Tsai ◽  
J.-W. Yeh
Keyword(s):  
High Entropy Alloys ◽  
High Entropy ◽  
Sluggish Diffusion

scholarly journals Kinetic ways of tailoring phases in high entropy alloys

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Feng He ◽  
Zhijun Wang ◽  
Yiyan Li ◽  
Qingfeng Wu ◽  
Junjie Li ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Equilibrium Phase ◽  
High Entropy Alloys ◽  
Kinetic Effect ◽  
Phase Selection ◽  
High Entropy ◽  
Comprehensive Performance ◽  
Sluggish Diffusion ◽  
Kinetics Of ◽  
Theoretical Analyses

Abstract The comprehensive performance of high entropy alloys (HEAs) depends on the phase selection significantly. However, up to now, investigations of the phase selection in HEAs mainly focused on the thermodynamic equilibrium phase, while kinetic ways of tailoring the phases in HEAs are seldom considered. In HEAs, the kinetics of sluggish diffusion and the numerous possible phases make the kinetics of phase transformation more complex and intriguing. Here, the kinetic effect in CoCrFeNiTi0.4 HEAs was investigated to reveal the possibility of controlling phase selection via kinetic ways for HEAs. The σ, γ′ and R phases in the CoCrFeNiTi0.4 HEA can be controlled under different cooling rate both in solidification and solid transformation. The theoretical analyses revealed the kinetic effect on phase selection. The method proposed here, tailoring the phases with different kinetic ways, could be used to prepare promising HEAs with very rich composition design.

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

2018 ◽  
Vol 17 ◽  
pp. 69-104 ◽  
Author(s):  
Sergiy V. Divinski ◽  
Alexander V. Pokoev ◽  
Neelamegan Esakkiraja ◽  
Aloke Paul
Keyword(s):  
High Temperature ◽  
Experimental Analysis ◽  
Dominant Role ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Number Of Components ◽  
Sluggish Diffusion

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 interdi usion, in fact based on an improper analysis, were cited in hundreds of articles to state the presence of sluggishness of di usion rates in high entropy alloys.

Fundamental Core Effects in Transition Metal High-Entropy Alloys: “High-Entropy” and “Sluggish Diffusion” Effects

2021 ◽  
Vol 29 ◽  
pp. 75-93
Author(s):  
Abhishek Mehta ◽  
Yong Ho Sohn
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
High Temperature Strength ◽  
High Entropy Alloys ◽  
High Temperature Stability ◽  
High Entropy ◽  
Diffusion Effects ◽  
Initial Work ◽  
Entropy Effect ◽  
Sluggish Diffusion

High entropy alloys (HEAs) are equimolar multi-principal-element alloys (MPEAs) that are different from traditional solvent-based multicomponent alloys based on the concept of alloy design. Based on initial work by Yeh and co-workers, HEAs were postulated to exhibit four “core” effects: high entropy, sluggish diffusion, lattice distortion, and cocktail effect. Out of these four proposed core effects, “high entropy” and “sluggish diffusion” effects were most debated in the literature as these core effects directly affect the thermodynamic and kinetic understanding of HEAs. The initial work on HEAs by several researchers utilized these effects to indirectly support the experimentally observed “unique” properties, without independent investigation of these core effects. The presumed implications of these core effects resulted in justification or generalization of properties to all HEAs, e.g., all HEAs should exhibit high temperature stability based on high entropy effect, high temperature strength owing to limited grain growth, good diffusion barrier application due to sluggish diffusion kinetics, etc. However, many recent studies have challenged these core effects, and suggested that not all HEAs were observed to exhibit these core effects.

Demystifying the sluggish diffusion effect in high entropy alloys

2019 ◽  
Vol 783 ◽  
pp. 193-207 ◽  
Author(s):  
Juliusz Dąbrowa ◽  
Marek Zajusz ◽  
Witold Kucza ◽  
Grzegorz Cieślak ◽  
Katarzyna Berent ◽  
...  
Keyword(s):  
High Entropy Alloys ◽  
Diffusion Effect ◽  
High Entropy ◽  
Sluggish Diffusion

scholarly journals State-of-the-Art Diffusion Studies in the High Entropy Alloys

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 347 ◽  
Author(s):  
Juliusz Dąbrowa ◽  
Marek Danielewski
Keyword(s):  
High Temperature ◽  
Materials Science ◽  
Driving Forces ◽  
State Of The Art ◽  
Point Of View ◽  
High Entropy Alloys ◽  
Diffusion Effect ◽  
High Entropy ◽  
Diffusion Studies ◽  
Sluggish Diffusion

The development of the high entropy alloys (HEAs) is amongst the most important topics in the field of materials science during the last two decades. The concept of multicomponent, near-equimolar systems has been already applied to the number of other systems, including oxides, carbides, diborides, silicides, and it can be expected that other groups of materials will follow. One of the main driving forces for the development of HEAs is the so-called “four core effects”: high entropy effects, severe lattice distortion, cocktail effect, and sluggish diffusion effect. Their existence and extent has been a subject of heated discussion. Probably the least studied of them is the sluggish diffusion effect, which is of the, especially, high importance from the point of view of the most possible applications of HEAs—as high-temperature materials. Its alleged existence carries a promise of obtaining materials with superior mechanical properties, higher creep resistance, and less susceptibility to high-temperature corrosion. In the current review, the state-of-the-art of diffusion studies in HEAs was presented, as well as the resulting conclusions concerning the existence of the sluggish diffusion effect. Based on the literature analysis, it can be stated that there is no experimental evidence, which would support the existence of the sluggish diffusion in HEAs on the level of tracer and self-diffusivities. Nevertheless, it can be pointed out that our current state of knowledge on the diffusion in HEAs is still far from complete; therefore, further directions of studies are proposed.

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