scholarly journals High-Entropy Alloys: Formation and Properties

2018 ◽  
Author(s):  
Michael C. Gao ◽  
Paul D. Jablonski ◽  
Jeffrey A. Hawk ◽  
David E. Alman
Keyword(s):  
Density Functional ◽  
Thermomechanical Processing ◽  
Dynamics Simulation ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
Ongoing Research ◽  
High Entropy ◽  
Face Centered

This paper presents ongoing research at NETL aimed at gaining fundamental understanding of high-entropy alloys (HEAs) formation and their properties, and developing highperformance HEAs for high-temperature fossil energy applications. First-principles density functional theory (DFT), Monte Carlo simulation, and molecular dynamics simulation are carried out to predict enthalpy of formation, the entropy sources (i.e., configurational entropy, vibrational entropy, and electronic entropy), and elastic properties of model single-phase HEAs with the face-centered cubic, body-centered cubic and hexagonal closed-packed structures. Classical elastic theory, which considers the interactions between dislocations and elastic fields of solutes, has also been used to predict solid solution strengthening. Large-size (∼7.5 kg) HEAs ingots are produced using vacuum induction melting and electroslag remelting methods, followed by homogenization treatment resulting in greater than 99% homogeneity. Subsequent thermomechanical processing produces fully-wrought face-centered cubic microstructures. The tensile behavior for these alloys have been determined as a function of temperature, and based on these results screening creep tests have been performed at selected temperatures and stresses.

Effect of Interstitial Elements on the Cryogenic Mechanical Behavior of FCC High Entropy Alloys

2021 ◽  
Vol 1016 ◽  
pp. 1386-1391
Author(s):  
Anastasia Semenyuk ◽  
Margarita Klimova ◽  
Sergey Zherebtsov ◽  
Nikita Stepanov
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Thermomechanical Processing ◽  
Induction Melting ◽  
High Entropy Alloys ◽  
Strengthening Effect ◽  
Face Centered Cubic ◽  
High Entropy ◽  
C And N ◽  
Interstitial Elements

High entropy alloys (HEAs) with face-centered cubic (fcc) structure, namely equiatomic CoCrFeMnNi alloy, have attracted considerable attention because of impressive cryogenic mechanical properties – strength, ductility, and fracture toughness. Further increase of the properties can be achieved, for example, by proper alloying. A particularly attractive option is the addition of interstitial elements like carbon or nitrogen. In present work, a series of CoCrFeMnNi-based alloys with different amounts of C and N (0-2 at.%) was prepared by induction melting. The alloys doped with C had lower Cr content to increase the solubility of carbon in the fcc solid solution. It was revealed that the solid solution strengthening effect of both C and N is significantly increased when the testing temperature decreases from 293K to 77K. The effect of thermomechanical processing on the structure and mechanical properties of the alloys is analyzed.

scholarly journals Effects of Different Contents of Each Component on the Structural Stability and Mechanical Properties of Co-Cr-Fe-Ni High-Entropy Alloys

2021 ◽  
Vol 11 (6) ◽  
pp. 2832
Author(s):  
Haibo Liu ◽  
Cunlin Xin ◽  
Lei Liu ◽  
Chunqiang Zhuang
Keyword(s):  
Mechanical Properties ◽  
Structural Stability ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
Obvious Effect ◽  
High Entropy ◽  
Precise Control ◽  
Component Content ◽  
Face Centered ◽  
And Performance

The structural stability of high-entropy alloys (HEAs) is closely related to their mechanical properties. The precise control of the component content is a key step toward understanding their structural stability and further determining their mechanical properties. In this study, first-principle calculations were performed to investigate the effects of different contents of each component on the structural stability and mechanical properties of Co-Cr-Fe-Ni HEAs based on the supercell model. Co-Cr-Fe-Ni HEAs were constructed based on a single face-centered cubic (FCC) solid solution. Elemental components have a clear effect on their structure and performance; the Cr and Fe elements have an obvious effect on the structural stability and equilibrium lattice constant, respectively. The Ni elements have an obvious effect on stiffness. The Pugh ratios indicate that Cr and Ni addition may increase ductility, whereas Co and Fe addition may decrease it. With increasing Co and Fe contents or decreasing Cr and Ni contents, the structural stability and stiffness of Co-Cr-Fe-Ni HEAs are improved. The structural stability and mechanical properties may be related to the strength of the metallic bonding and covalent bonding inside Co-Cr-Fe-Ni HEAs, which, in turn, is determined by the change in element content. Our results provide the underlying insights needed to guide the optimization of Co-Cr-Fe-Ni HEAs with excellent mechanical properties.

Insights into Defect-Mediated Nucleation of Equilibrium B2 Phase in Face-Centered Cubic High-Entropy Alloys

JOM ◽  
2021 ◽  
Author(s):  
Abhishek Sharma ◽  
Bharat Gwalani ◽  
Sriswaroop Dasari ◽  
Deep Choudhuri ◽  
Yao-Jen Chang ◽  
...  
Keyword(s):  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
B2 Phase ◽  
Face Centered

Bimodality of incipient plastic strength in face-centered cubic high-entropy alloys

2021 ◽  
Vol 202 ◽  
pp. 124-134
Author(s):  
Yakai Zhao ◽  
Jeong-Min Park ◽  
Jae-il Jang ◽  
Upadrasta Ramamurty
Keyword(s):  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Plastic Strength ◽  
Face Centered

Effects of Mn Content and Grain Size on Hydrogen Embrittlement Susceptibility of Face-Centered Cubic High-Entropy Alloys

2020 ◽  
Vol 51 (11) ◽  
pp. 5612-5616
Author(s):  
Motomichi Koyama ◽  
Haoyu Wang ◽  
Virendra Kumar Verma ◽  
Kaneaki Tsuzaki ◽  
Eiji Akiyama
Keyword(s):  
Grain Size ◽  
Hydrogen Embrittlement ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Mn Content ◽  
Face Centered

scholarly journals Metalloid substitution elevates simultaneously the strength and ductility of face-centered-cubic high-entropy alloys

2021 ◽  
pp. 117571
Author(s):  
Daixiu Wei ◽  
Liqiang Wang ◽  
Yongjie Zhang ◽  
Wu Gong ◽  
Tomohito Tsuru ◽  
...  
Keyword(s):  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Face Centered ◽  
Strength And Ductility

scholarly journals Effect of Molybdenum Additives on Corrosion Behavior of (CoCrFeNi)100−xMox High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (12) ◽  
pp. 908 ◽  
Author(s):  
Wenrui Wang ◽  
Jieqian Wang ◽  
Honggang Yi ◽  
Wu Qi ◽  
Qing Peng
Keyword(s):  
Corrosion Behavior ◽  
Compressive Strain ◽  
Compressive Yield Strength ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
Σ Phase ◽  
High Entropy ◽  
Passivation Film ◽  
Face Centered ◽  
Mo Content

The present work investigates the influence of micro-alloyed Mo on the corrosion behavior of (CoCrFeNi)100−xMox high-entropy alloys. All of the (CoCrFeNi)100−xMox alloys exhibit a single face-centered cubic (FCC) solid solution. However, the (CoCrFeNi)97Mo3 alloy exhibits an ordered sigma (σ) phase enriched in Cr and Mo. With the increase of x (the Mo content) from 1 to 3, the hardness of the (CoCrFeNi)100−xMox alloys increases from 124.8 to 133.6 Vickers hardness (HV), and the compressive yield strength increases from 113.6 MPa to 141.1 MPa, without fracture under about a 60% compressive strain. The potentiodynamic polarization curve in a 3.5% NaCl solution indicates that the addition of Mo has a beneficial effect on the corrosion resistance to some certain extent, opposed to the σ phase. Furthermore, the alloys tend to form a passivation film in the 0.5 M H2SO4 solution in order to inhibit the progress of the corrosion reaction as the Mo content increases.

scholarly journals Magnetic Properties and Microstructure of FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) High-Entropy Alloys

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 872 ◽  
Author(s):  
Zhong Li ◽  
Chenxu Wang ◽  
Linye Yu ◽  
Yong Gu ◽  
Minxiang Pan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Tc ◽  
Soft Magnets ◽  
High Entropy ◽  
Face Centered ◽  
Fcc Phase ◽  
Bcc Phase ◽  
Curie Temperatures

The present work exhibits the effects of Sn addition on the magnetic properties and microstructure of FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) high-entropy alloys (HEAs). The results show all the samples consist of a mixed structure of face-centered-cubic (FCC) phase and body-centered-cubic (BCC) phase. The addition of Sn promotes the formation of BCC phase, and it also affects the shape of Cu-rich nano-precipitates in BCC matrix. It also shows that the Curie temperatures (Tc) of the FCC phase and the saturation magnetization (Ms) of the FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs increase greatly while the remanence (Br) decreases after the addition of Sn into FeCoNi(CuAl)0.8 HEA. The thermomagnetic curves indicate that the phases of the FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs will transform from FCC with low Tc to BCC phase with high Tc at temperature of 600–700 K. This work provides a new idea for FeCoNi(CuAl)0.8Snx (0 ≤ x ≤ 0.10) HEAs for their potential application as soft magnets to be used at high temperatures.

scholarly journals Influence of Ti on the Tensile Properties of the High-Strength Powder Metallurgy High Entropy Alloys

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 578 ◽  
Author(s):  
Igor Moravcik ◽  
Stepan Gamanov ◽  
Larissa Moravcikova-Gouvea ◽  
Zuzana Kovacova ◽  
Michael Kitzmantel ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Tensile Properties ◽  
High Strength ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Solid Solution Strengthening ◽  
Plasma Sintering ◽  
Annealing Heat Treatment ◽  
Face Centered

The focus of this study is the evaluation of the influence of Ti concentration on the tensile properties of powder metallurgy high entropy alloys. Three Ni1.5Co1.5CrFeTiX alloys with X = 0.3; 0.5 and 0.7 were produced by mechanical alloying and spark plasma sintering. Additional annealing heat treatment at 1100 °C was utilized to obtain homogenous single-phase face centered cubic (FCC) microstructures, with minor oxide inclusions. The results show that Ti increases the strength of the alloys by increasing the average atomic size misfit i.e., solid solution strengthening. An excellent combination of mechanical properties can be obtained by the proposed method. For instance, annealed Ni1,5Co1,5CrFeTi0.7 alloy possessed the ultimate tensile strength as high as ~1600 MPa at a tensile ductility of ~9%, despite the oxide contamination. The presented results may serve as a guideline for future alloy design of novel, inclusion-tolerant materials for sustainable metallurgy.

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