scholarly journals Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7506
Author(s):  
Boris B. Straumal ◽  
Anna Korneva ◽  
Gabriel A. Lopez ◽  
Alexei Kuzmin ◽  
Eugen Rabkin ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Solid Phase ◽  
High Entropy Alloys ◽  
Grain Boundary Engineering ◽  
Phase Form ◽  
High Entropy ◽  
The Matrix ◽  
Tie Lines ◽  
Grain Boundary Wetting

In this review, the phenomenon of grain boundary (GB) wetting by the second solid phase is analyzed for the high entropy alloys (HEAs). Similar to the GB wetting by the liquid phase, the GB wetting by the second solid phase can be incomplete (partial) or complete. In the former case, the second solid phase forms in the GB of a matrix, the chain of (usually lenticular) precipitates with a certain non-zero contact angle. In the latter case, it forms in the GB continuous layers between matrix grains which completely separate the matrix crystallites. The GB wetting by the second solid phase can be observed in HEAs produced by all solidification-based technologies. The particle chains or continuous layers of a second solid phase form in GBs also without the mediation of a liquid phase, for example by solid-phase sintering or coatings deposition. To describe the GB wetting by the second solid phase, the new GB tie-lines should be considered in the two- or multiphase areas in the multicomponent phase diagrams for HEAs. The GB wetting by the second solid phase can be used to improve the properties of HEAs by applying the so-called grain boundary engineering methods.

scholarly journals The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1881
Author(s):  
Boris B. Straumal ◽  
Anna Korneva ◽  
Alexei Kuzmin ◽  
Gabriel A. Lopez ◽  
Eugen Rabkin ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Principal Components ◽  
Contact Angles ◽  
Second Phase ◽  
High Entropy Alloys ◽  
Grain Boundary Engineering ◽  
High Entropy ◽  
Tie Lines ◽  
Grain Boundary Wetting

In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines Twmin and Twmax in the multicomponent HEA phase diagrams. The so-called grain-boundary engineering of HEAs permits the use of GB wetting to improve the HEAs’ properties or, alternatively, its exclusion if the GB layers of a second phase are detrimental.

scholarly journals Grain Boundary Wetting Phenomena in High Entropy Alloys Containing Nitrides, Carbides, Borides, Silicides, and Hydrogen: A Review

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1540
Author(s):  
Boris Straumal ◽  
Eugen Rabkin ◽  
Gabriel A. Lopez ◽  
Anna Korneva ◽  
Alexei Kuzmin ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Chemical Engineering ◽  
Solid Phase ◽  
Second Phase ◽  
High Entropy Alloys ◽  
High Entropy ◽  
The Matrix ◽  
Tie Lines ◽  
Grain Boundary Wetting ◽  
A Chain

In this review, we analyze the structure of multicomponent alloys without principal components (they are also called high entropy alloys—HEAs), containing not only metals but also hydrogen, nitrogen, carbon, boron, or silicon. In particular, we discuss the phenomenon of grain boundary (GB) wetting by the melt or solid phase. The GB wetting can be complete or incomplete (partial). In the former case, the grains of the matrix are completely separated by the continuous layer of the second phase (solid or liquid). In the latter case of partial GB wetting, the second solid phase forms, between the matrix grains, a chain of (usually lenticular) precipitates or droplets with a non-zero value of the contact angle. To deal with the morphology of GBs, the new GB tie-lines are used, which can be constructed in the two- or multiphase areas of the multidimensional HEAs phase diagrams. The GBs in HEAs in the case of complete or partial wetting can also contain hydrides, nitrides, carbides, borides, or silicides. Thus, GB wetting by the hydrides, nitrides, carbides, borides, or silicides can be used in the so-called grain boundary chemical engineering in order to improve the properties of respective HEAs.

scholarly journals Liquid Phase Separation in Ag-Co-Cr-Fe-Mn-Ni, Co Cr-Cu-Fe-Mn-Ni and Co-Cr-Cu-Fe-Mn-Ni-B High Entropy Alloys for Biomedical Application

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 527 ◽  
Author(s):  
Takeshi Nagase ◽  
Mitsuharu Todai ◽  
Takayoshi Nakano
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Biomedical Application ◽  
Melting Process ◽  
Liquid Phase Separation ◽  
Heat Of Mixing ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Metallic Biomaterials ◽  
Fundamental Research

The liquid phase separation (LPS) behavior in Co-Cr-based high-entropy alloys (HEAs) is an important target for the development of Co-Cr-based HEAs for metallic biomaterials (BioHEAs). The solidification microstructure in Ag-Co-Cr-Fe-Mn-Ni-Ag, Co-Cr-Cu-Fe-Mn-Ni-Cu, and Co-Cr-Cu-Fe-Mn-Ni-B HEAs, which were designed as the combination of the equiatomic CoCrFeMnNi with Ag, Cu, and the interstitial element of B, was investigated as the fundamental research of LPS in Co-Cr-based HEAs. Ingots of equiatomic AgCoCrFeMnNi, equiatomic CoCrCuFeMnNi, non-equiatomic CoCrCuxFeMnNi (x = 2, 3), and CoCrCuxFeMnNiB0.2 (x = 1, 2, 3) with a small amount of B were fabricated using the arc-melting process. A macroscopic phase-separated structure was observed in the ingots of the equiatomic AgCoCrFeMnNi and CoCrCuxFeMnNiB0.2 (x = 2, 3) HEAs. The addition of a small amount of B enhanced the LPS tendency in the Co-Cr-Fe-Mn-Ni-Cu HEAs. The LPS behavior was discussed through the heat of mixing and computer coupling of phase diagrams and thermochemistry (CALPHAD).

Pressure Influence on the AlCrFeNiMn/Graphite High Entropy Composite Microhardness

2017 ◽  
Vol 750 ◽  
pp. 9-14
Author(s):  
Gabriela Popescu ◽  
Mihai Branzei ◽  
Cristian Aurelian Popescu ◽  
Alecs Andrei Matei ◽  
Roxana Trusca ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
High Entropy Alloys ◽  
X Rays ◽  
High Entropy ◽  
Graphite Particles ◽  
The Matrix ◽  
Microhardness And Microstructure ◽  
Near Net Shape ◽  
Chemical Distribution ◽  
Scanning Electron

During the last years, mechanical alloying technique for high entropy alloys (HEAs) has been more often approached due to the good homogenous chemical distribution and near net shape technology provided by the respectively process. A new composite material having the matrix as HEA reinforced with graphite particles was designed. The graphite particles addition in the high entropy matrix (AlCrFeNiMn) improves the particles weldability during mechanical alloying and assures a good creep behavior for the final product. The aim of this paper is to investigate the pressure influence on the microhardness as dependence of sintering parameters which can be reflected also on the microstructure. The high entropy composite was completely alloyed after 40 hours of milling. The obtained composite was pressed using different pressures values in order to investigate the pressure influence on the microhardness and microstructure. The samples were investigated using optical microscopy, scanning electron microscopy, X-rays diffraction and microhardness tests. The microhardness values for all the samples were between 300 – 700 HV.

Low Angle Grain Boundary Dewetting in Sapphire

2001 ◽  
Vol 7 (S2) ◽  
pp. 384-385
Author(s):  
B.J. Hockey ◽  
M-K. Kang ◽  
S.M. Wiederhorn ◽  
J.E. Blendell
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Transmission Electron ◽  
Wide Range ◽  
Grain Boundary Wetting ◽  
Tape Cast ◽  
Single Boundary ◽  
Current Emphasis

The structure and composition of low angle grain boundaries produced in sapphire by a liquid phase sintering process were investigated by conventional and high resolution transmission electron microscopy (CTEM and HRTEM, respectively). Considering the current emphasis on producing ceramics with textured microstructures for various applications, the question of grain boundary wetting vs. dewetting has become a relevant issue to determining the microstructure development and the properties of these liquid phase sintered materials. Accordingly, the present study was designed to cover a wide range of tilt misorientations, twist misorientations, and boundary orientations.The boundaries were formed by the directed growth of two sapphire plates, both having nominal <0001>, , or surface orientations through an alumina tape-cast containing an anorthite composition glass phase. After an initial hot-pressing stage, followed by an anneal at 1600° C for 200 hours, the samples typically contained a single boundary delineated by isolated pockets of entrapped glass, Fig. 1.

Inversed solid-phase grain boundary wetting in the Al–Zn system

2011 ◽  
Vol 46 (12) ◽  
pp. 4349-4353 ◽  
Author(s):  
S. G. Protasova ◽  
O. A. Kogtenkova ◽  
B. B. Straumal ◽  
P. Zięba ◽  
B. Baretzky
Keyword(s):  
Grain Boundary ◽  
Solid Phase ◽  
Grain Boundary Wetting

Grain boundary engineering and its implications on corrosion behaviour of equiatomic CoCrFeMnNi high entropy alloy

2021 ◽  
pp. 161500
Author(s):  
Hemanth Thota ◽  
R. Jeyaraam ◽  
Lipika Rani Bairi ◽  
Aditya Srinivasan Tirunilai ◽  
Alexander Kauffmann ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Corrosion Behaviour ◽  
High Entropy Alloy ◽  
Grain Boundary Engineering ◽  
High Entropy

scholarly journals Evaluation of Radiation Response in CoCrFeCuNi High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 835 ◽  
Author(s):  
Yang Wang ◽  
Kun Zhang ◽  
Yihui Feng ◽  
Yansen Li ◽  
Weiqi Tang ◽  
...  
Keyword(s):  
Ion Irradiation ◽  
Ion Beam ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
Thermal Spike ◽  
High Entropy ◽  
Arc Melting ◽  
The Matrix ◽  
Volume Swelling

CoCrFeCuNi high-entropy alloys (HEAs) prepared by arc melting were irradiated with a 100 keV He+ ion beam. Volume swelling and hardening induced by irradiation were evaluated. When the dose reached 5.0 × 1017 ions/cm2, the Cu-rich phases exhibited more severe volume swelling compared with the matrix phases. This result indicated that the Cu-rich phases were favorable sites for the nucleation and gathering of He bubbles. X-ray diffraction indicated that all diffraction peak intensities decreased regularly. This reduction suggested loosening of the irradiated layer, thereby reducing crystallinity, under He+ ion irradiation. The Nix-Gao model was used to fit the measured hardness in order to obtain a hardness value H0 that excludes the indentation size effect. At ion doses of 2.5 × 1017 ions/cm2 and 5.0 × 1017 ions/cm2, the HEAs showed obvious hardening, which could be attributed to the formation of large amounts of irradiation defects. At the ion dose of 1.0 × 1018 ions/cm2, hardening was reduced, owing to the exfoliation of the original irradiation layer, combined with recovery induced by long-term thermal spike. This study is important to explore the potential uses of HEAs under extreme irradiation conditions.

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