scholarly journals Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 54
Author(s):  
Boris B. Straumal ◽  
Roman Kulagin ◽  
Brigitte Baretzky ◽  
Natalia Yu. Anisimova ◽  
Mikhail V. Kiselevskiy ◽  
...  
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Phase Transformations ◽  
Single Phase ◽  
Materials Science ◽  
Bulk Solution ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

Developing Superplasticity in High-Entropy Alloys Processed by Severe Plastic Deformation

2018 ◽  
Vol 941 ◽  
pp. 1059-1064
Author(s):  
Hamed Shahmir ◽  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Low Temperatures ◽  
Elevated Temperatures ◽  
Tensile Elongation ◽  
Metallic Alloys ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Principal Elements

High-entropy alloys (HEAs) are currently attracting much interest because they offer unique properties and good ductility at low temperatures. These materials are of interest primarily because they contain five or more principal elements, with each element having a concentration between 5 and 35 at. %, and yet they have very simple structures based on solid solution phases. Superplasticity is defined formally as a tensile elongation without failure of at least 400% and very recent experiments have shown that the HEAs also have a potential for exhibiting superplastic ductilities when testing at elevated temperatures. Since superplasticity requires a very small grain size, typically <10 μm, it is feasible to process HEAs using severe plastic deformation in order to introduce significant grain refinement. The objective of this review is to summarize the recent results showing superplasticity in HEAs and to compare directly the superplastic flow in HEAs and superplasticity in conventional metallic alloys.

A review on phase prediction in high entropy alloys

2021 ◽  
pp. 095440622110089
Author(s):  
Vinay Kumar Soni ◽  
S Sanyal ◽  
K Raja Rao ◽  
Sudip K Sinha
Keyword(s):  
Solid Solution ◽  
Phase Formation ◽  
Single Phase ◽  
High Entropy Alloy ◽  
High Entropy Alloys ◽  
Modeling Tools ◽  
High Entropy ◽  
Recent Developments ◽  
Phase Prediction ◽  
The Stability

The formation of single phase solid solution in High Entropy Alloys (HEAs) is essential for the properties of the alloys therefore, numerous approach were proposed by many researchers to predict the stability of single phase solid solution in High Entropy Alloy. The present review examines some of the recent developments while using computational intelligence techniques such as parametric approach, CALPHAD, Machine Learning etc. for prediction of various phase formation in multicomponent high entropy alloys. A detail study of this data-driven approaches pertaining to the understanding of structural and phase formation behaviour of a new class of compositionally complex alloys is done in the present investigation. The advantages and drawbacks of the various computational are also discussed. Finally, this review aims at understanding several computational modeling tools complying the thermodynamic criteria for phase formation of novel HEAs which could possibly deliver superior mechanical properties keeping an aim at advanced engineering applications.

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.

scholarly journals Phase Decomposition of a Single-Phase AlTiVNb High-Entropy Alloy after Severe Plastic Deformation and Annealing

2017 ◽  
Vol 19 (4) ◽  
pp. 1600674 ◽  
Author(s):  
Benjamin Schuh ◽  
Bernhard Völker ◽  
Verena Maier-Kiener ◽  
Juraj Todt ◽  
Jiehua Li ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Single Phase ◽  
High Entropy Alloy ◽  
Phase Decomposition ◽  
High Entropy

Formation rules of single phase solid solution in high entropy alloys

2016 ◽  
pp. 1-5 ◽  
Author(s):  
L. Jiang ◽  
Y.P. Lu ◽  
H. Jiang ◽  
T.M. Wang ◽  
B.N. Wei ◽  
...  
Keyword(s):  
Solid Solution ◽  
Single Phase ◽  
High Entropy Alloys ◽  
High Entropy

Microstructure and Properties of Alloys with Equal Atomic Principal Components

2013 ◽  
Vol 765-767 ◽  
pp. 3143-3146
Author(s):  
Yan Ping Wang ◽  
Yu Zhuang ◽  
Jian Chen Li
Keyword(s):  
Solid Solution ◽  
Principal Components ◽  
Argon Atmosphere ◽  
Second Phase ◽  
High Entropy Alloys ◽  
Arc Furnace ◽  
Phase Precipitation ◽  
High Entropy ◽  
Bcc Structure ◽  
Fcc Structure

Four high-entropy alloys are prepared by an arc furnace under argon atmosphere. The microstructure and the properties of the alloys are investigated. The results show that NiCrCuCoFe alloy consists of a single FCC solid solution. When Al presents in the alloys, the microstructures of the alloys change to a BCC+ FCC solid solution. It is indicated that Al element promotes the formation of BCC solid solution, and Si and Mn promote the formation of complicated compounds. The hardness of alloys with BCC structure is higher than that of the alloys with FCC structure. The complicated compounds are formed, the hardness increases further. The highest hardness of the alloys reaches 882 HV due to the strengthening of the second phase precipitation.

scholarly journals Plastic deformation of solid-solution strengthened Hf-Nb-Ta-Ti-Zr body-centered cubic medium/high-entropy alloys

2021 ◽  
Vol 200 ◽  
pp. 113927
Author(s):  
Rajeshwar R. Eleti ◽  
Nikita Stepanov ◽  
Nikita Yurchenko ◽  
Denis Klimenko ◽  
Sergey Zherebtsov
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
High Entropy Alloys ◽  
Body Centered Cubic ◽  
High Entropy

PROSPECTS FOR THE USE OF HIGH-ENTROPY ALLOYS FOR RESTORING MACHINE PARTS BY ATMOSPHERIC PLASMA DEPOSITION

2021 ◽  
Vol 72 (1) ◽  
pp. 20-27
Author(s):  
A.M. KADIRMETOV ◽  
◽  
D.A. POPOV ◽  
E.V. SNYATKOV ◽  
◽  
...  
Keyword(s):  
Solid Solution ◽  
Single Phase ◽  
Plasma Deposition ◽  
Atmospheric Plasma ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Plasma Sputtering ◽  
Machine Parts ◽  
Metal Materials ◽  
Ratio Of Components

A brief analysis of the most common methods for producing multicomponent alloys, including high-entropy alloys (HES), is presented in terms of their use as an alternative to coatings made of traditional structural metal materials. Preliminary studies of the microstructure and phase compo-sition of the coating obtained by plasma deposition of FeCoCrAlTiCuMo powder in the equiatom-ic ratio of components are presented. The results of the research showed the possibility of obtain-ing a multicomponent single-phase solid solution by plasma sputtering and indicated the feasibil-ity of its further study.

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