Monocrystalline elastic constants of fcc-CrMnFeCoNi high entropy alloy

MRS Advances ◽  
2017 ◽  
Vol 2 (27) ◽  
pp. 1429-1434 ◽  
Author(s):  
Katsushi Tanaka ◽  
Takeshi Teramoto ◽  
Ryo Ito
Keyword(s):  
Solid Solution ◽  
Elastic Constants ◽  
Room Temperature ◽  
Entropy Change ◽  
High Entropy Alloy ◽  
Melting Points ◽  
High Entropy ◽  
Fcc Metals ◽  
Cauchy Pressure ◽  
Fcc Structure

ABSTRACTMono-crystalline elastic constants of equiatomic quinary Cr-Mn-Fe-Co-Ni high entropy alloy with the fcc structure have experimentally been determined by a resonance ultrasound spectroscopy at room temperature. The values of the bulk modulus of the high entropy alloy experimentally determined are similar to other conventional fcc metals when the values are normalized by the melting points. This indicates that the entropy change at melting is similar to that of conventional metals. The values of Pough’s index and the Cauchy pressure are determined as 1.79 and -11.6 GPa, respectively. When the ductility of the alloy is judged from the indices, the ductility of the high entropy alloy is limited. In order to explain the negative Cauchy pressure of the high entropy alloy, it is required to assume that relatively strong directional interatomic bondings like intermetallic compounds exist in the alloy though the crystal is disordered solid solution.

scholarly journals Elastic, Mechanical and Thermophysical properties of Single-Phase Quaternary ScTiZrHf High-Entropy Alloy

2021 ◽  
Vol 22 (4) ◽  
pp. 687-696
Author(s):  
Sachin Rai ◽  
Navin Chaurasiya ◽  
Pramod K. Yadawa
Keyword(s):  
Mechanical Properties ◽  
Elastic Constants ◽  
Room Temperature ◽  
Single Phase ◽  
Mechanical Characterization ◽  
Ultrasonic Attenuation ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Different Temperatures ◽  
Ultrasonic Parameters

Consequent to the interaction potential model, the high-order elastic constants at high entropy alloys in single-phase quaternary ScTiZrHf have been calculated at different temperatures. Elastic constants of second order (SOECs) helps to determine other ultrasonic parameters. With the help of SOECs other elastic moduli, bulk modulus, shear modulus, Young’s modulus, Pugh’s ratio, elastic stiffness constants and Poisson’s ratio are estimated at room temperature for elastic and mechanical characterization. The other ultrasonic parameters are calculated at room temperature for elastic and mechanical characterization. The temperature variation of ultrasonic velocities along the crystal's z-axis is evaluated using SOECs. The temperature variation of the  average debye velocity and the thermal relaxation time (τ) are also estimated along this orientation axis. The ultrasonic properties correlated with elastic, thermal and mechanical properties which is temperature dependent is also discussed. The ultrasonic attenuation due to phonon – phonon (p-p) interactions is also calculated at different temperatures. In the study of ultrasonic attenuation such as a function of temperature, thermal conductivity appears to be main contributor and p- p interactions are the responsible reason of attenuation and found that the mechanical properties of the high entropy alloy ScTiZrHf are superior at room temperature.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

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.

On the room temperature deformation mechanisms of a TiZrHfNbTa refractory high-entropy alloy

2015 ◽  
Vol 645 ◽  
pp. 255-263 ◽  
Author(s):  
J.-Ph. Couzinié ◽  
L. Lilensten ◽  
Y. Champion ◽  
G. Dirras ◽  
L. Perrière ◽  
...  
Keyword(s):  
Room Temperature ◽  
Deformation Mechanisms ◽  
Temperature Deformation ◽  
High Entropy Alloy ◽  
High Entropy

scholarly journals Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1290 ◽  
Author(s):  
Ning Liu ◽  
Chen Chen ◽  
Isaac Chang ◽  
Pengjie Zhou ◽  
Xiaojing Wang
Keyword(s):  
Molar Ratio ◽  
Mixing Enthalpy ◽  
High Entropy Alloy ◽  
Valence Electron Concentration ◽  
Face Centered Cubic ◽  
Distortion Parameter ◽  
Local Lattice Distortion ◽  
Phase Selection ◽  
High Entropy ◽  
Fcc Structure

To study the effect of alloy composition on phase selection in the CoCrCu0.1FeMoNi high-entropy alloy (HEA), Mo was partially replaced by Co, Cr, Fe, and Ni. The microstructures and phase selection behaviors of the CoCrCu0.1FeMoNi HEA system were investigated. Dendritic, inter-dendritic, and eutectic microstructures were observed in the as-solidified HEAs. A simple face centered cubic (FCC) single-phase solid solution was obtained when the molar ratio of Fe, Co, and Ni was increased to 1.7 at the expense of Mo, indicating that Fe, Co, and Ni stabilized the FCC structure. The FCC structure was favored at the atomic radius ratio δ ≤ 2.8, valence electron concentration (VEC) ≥ 8.27, mixing entropy ΔS ≤ 13.037, local lattice distortion parameter α2 ≤ 0.0051, and ΔS/δ2 > 1.7. Mixed FCC + body centered cubic (BCC) structures occurred for 4.1 ≤ δ ≤ 4.3 and 7.71 ≤ VEC ≤ 7.86; FCC or/and BCC + intermetallic (IM) mixtures were favored at 2.8 ≤ δ ≤ 4.1 or δ > 4.3 and 7.39 < VEC ≤ 8.27. The IM phase is favored at electronegativity differences greater than 0.133. However, ΔS, α2, and ΔS/δ2 were inefficient in identifying the (FCC or/and BCC + IM)/(FCC + BCC) transition. Moreover, the mixing enthalpy cannot predict phase structures in this system.

Vanishing of room-temperature slip avalanches in a face-centered-cubic high-entropy alloy by ultrafine grain formation

2018 ◽  
Vol 155 ◽  
pp. 99-103 ◽  
Author(s):  
Jian Qiang ◽  
Koichi Tsuchiya ◽  
Haoyan Diao ◽  
Peter K. Liaw
Keyword(s):  
Room Temperature ◽  
Ultrafine Grain ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Grain Formation ◽  
Face Centered

Solid State Amorphization and Alloy Parameters for High Entropy Alloys

2021 ◽  
Vol 1016 ◽  
pp. 990-996
Author(s):  
Takeshi Nagase
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Intermetallic Compounds ◽  
Electron Irradiation ◽  
Fast Electron ◽  
High Entropy Alloy ◽  
Solid Solution Formation ◽  
High Entropy ◽  
Solution Formation ◽  
State Amorphization

Fast electron irradiation can induce the solid-state amorphization (SSA) of many intermetallic compounds. The occurrence of SSA stimulated by fast electron irradiation was found in the Al0.5TiZrPdCuNi high-entropy alloy (HEA). The relationship between the occurrence of SSA in intermetallic compounds under fast electron irradiation and the empirical alloy parameters for predicting the solid-solution-formation tendency in HEAs was discussed. The occurrence of SSA in intermetallic compounds was hardly predicted, only by the alloy parameters of δ or ΔHmix, which have been widely used for predicting solid-solution formation in HEAs. All intermetallic compounds with ΔHmix ≤ -35 kJ/mol and those with δ ≥ 12.5 exhibit the occurrence of SSA. This implies that the intermetallic compounds with a largely negative ΔHmix value and a largely positive δ parameter are favorable for the occurrence of SSA.

scholarly journals Refractory High-Entropy HfTaTiNbZr-Based Alloys by Combined Use of Ball Milling and Spark Plasma Sintering: Effect of Milling Intensity

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1268 ◽  
Author(s):  
Natalia Shkodich ◽  
Alexey Sedegov ◽  
Kirill Kuskov ◽  
Sergey Busurin ◽  
Yury Scheck ◽  
...  
Keyword(s):  
Solid Solution ◽  
Ball Milling ◽  
Spark Plasma Sintering ◽  
Vickers Hardness ◽  
High Energy ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball

For the first time, a powder of refractory body-centered cubic (bcc) HfTaTiNbZr-based high-entropy alloy (RHEA) was prepared by short-term (90 min) high-energy ball milling (HEBM) followed by spark plasma sintering (SPS) at 1300 °C for 10 min and the resultant bulk material was characterized by XRD and SEM/EDX. The material showed ultra-high Vickers hardness (10.7 GPa) and a density of 9.87 ± 0.18 g/cm³ (98.7%). Our alloy was found to consist of HfZrTiTaNb-based solid solution with bcc structure as a main phase, a hexagonal closest packed (hcp) Hf/Zr-based solid solution, and Me2Fe phases (Me = Hf, Zr) as minor admixtures. Principal elements of the HEA phase were uniformly distributed over the bulk of HfTaTiNbZr-based alloy. Similar alloys synthesized without milling or in the case of low-energy ball milling (LEBM, 10 h) consisted of a bcc HEA and a Hf/Zr-rich hcp solid solution; in this case, the Vickers hardness of such alloys was found to have a value of 6.4 GPa and 5.8 GPa, respectively.

scholarly journals Laser Beam Welding of a Low Density Refractory High Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1351 ◽  
Author(s):  
Evgeniya Panina ◽  
Nikita Yurchenko ◽  
Sergey Zherebtsov ◽  
Nikita Stepanov ◽  
Gennady Salishchev ◽  
...  
Keyword(s):  
Laser Beam ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Laser Beam Welding ◽  
Base Material ◽  
Laves Phase ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Grains Refinement ◽  
Cast Condition

The effect of laser beam welding on the structure and properties of a Ti1.89NbCrV0.56 refractory high entropy alloy was studied. In particular, the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T ≥ 600 °C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particles. A columnar microstructure was formed in the welds; the thickness of the grains increased with the temperature of pre-heating before welding. The Laves phase particles were formed in the seams after welding at 600 °C or 800 °C, however, these particles were not observed after welding at room temperature or at 400 °C. Soaking at elevated temperatures did not change the microstructure of the base material considerably, however, “additional” small Laves particles formed at 600 °C or 800 °C. Tensile test of welded specimens performed at 750 °C resulted in the fracture of the base material because of the higher hardness of the welds. The latter can be associated with the bcc grains refinement in the seams.

A comparative study of a solid solution hardening in carbon-alloyed FeMnCrNiCo0.95C0.05 high-entropy alloy subjected to different thermal–mechanical treatments

2020 ◽  
pp. 129073
Author(s):  
Elena Astafurova ◽  
Evgenii Melnikov ◽  
Sergey Astafurov ◽  
Kseniya Reunova ◽  
Marina Panchenko ◽  
...  
Keyword(s):  
Solid Solution ◽  
Comparative Study ◽  
Solid Solution Hardening ◽  
High Entropy Alloy ◽  
Solution Hardening ◽  
High Entropy
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