scholarly journals Effect of Al Content on Phase Compositions of FeNiCoCrMo0.5Alx High Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1734
Author(s):  
Anton Semikolenov ◽  
Svetlana Shalnova ◽  
Victor Klinkov ◽  
Valentina Andreeva ◽  
Maria Salynova ◽  
...  
Keyword(s):  
Solid Solution ◽  
Phase Formation ◽  
Test Methods ◽  
Point Of View ◽  
High Entropy Alloy ◽  
Induction Melting ◽  
Σ Phase ◽  
High Entropy ◽  
Al Content ◽  
B2 Phase

The FeCoNiCrMo0.5Alx system with x up to 2.13 was analyzed from the point of view of evolution of the phase composition and microstructure. Cast samples were synthesized by induction melting and analyzed by X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers microhardness test methods. Phase compositions of these alloys in dependance on Al concentration consist of FCC solid solution, σ-phase, NiAl-based B2 phase, and BCC solid solution enriched with Mo and Cr. Phase formation principles were studied. Al dissolves in a FeCoNiCrMo0.5 FCC solid solution up to 8 at.%.; at higher concentrations, Al attracts Ni, removing it from FCC solid solution and forming the B2 phase. Despite Al not participating in σ-phase formation, an increase in Al concentration to about 20 at.% leads to a growth in the σ-phase fraction. The increase in the σ-phase was caused by an increase in the amount of B2 because the solubility of σ-forming Mo and Cr in B2 was less than that in the FCC solution. A further increase in Al concentration led to an excess of Mo and Cr in the solution, which formed a disordered BCC solid solution. The hardness of the alloys attained the maximum of 630 HV at 22 and 32 at.% Al.

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 Age Heat Treatment of Al0.5CoCrFe1.5NiTi0.5 High-Entropy Alloy

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 91
Author(s):  
Che-Fu Lee ◽  
Tao-Tsung Shun
Keyword(s):  
Cast Alloy ◽  
Dendritic Structure ◽  
Age Hardening ◽  
High Entropy Alloy ◽  
Σ Phase ◽  
High Entropy ◽  
The Matrix ◽  
B2 Phase ◽  
Fcc Phase ◽  
Bcc Phase

In this study, Al0.5CoCrFe1.5NiTi0.5 high-entropy alloy was heat-treated from 500 °C to 1200 °C for 24 h to investigate age-hardening phenomena and microstructure evolution. The as-cast alloy, with a hardness of HV430, exhibited a dendritic structure comprising an (Fe,Cr)-rich FCC phase and a (Ni,Al,Ti)-rich B2 phase, and the interdendrite exhibited a spinodal decomposed structure comprising an (Fe,Cr)-rich BCC phase and a (Ni,Al,Ti)-rich B2 phase. Age hardening and softening occurred at 500 °C to 800 °C and 900 °C to 1100 °C, respectively. We observed optimal age hardening at 700 °C, and alloy hardness increased to HV556. The hardening was attributed to the precipitation of the σ phase, and the softening was attributed to the dissolution of the σ phase back into the matrix and coarsening of the microstructure. The appearance of fine Widmanstätten precipitates formed by the (Al,Ti)-rich BCC phase and (Ni,Al,Ti)-rich B2 phase at 1200 °C led to secondary hardening.

Effect of Aging Temperature on Microstructure and Hardness of CoCrFeNiTi0.5 High Entropy Alloy

2014 ◽  
Vol 789 ◽  
pp. 48-53 ◽  
Author(s):  
Yong Dong ◽  
Qiu Shi Chen ◽  
Yi Ping Lu ◽  
Peng Chao Zhang ◽  
Ting Ju Li
Keyword(s):  
Aging Temperature ◽  
Volume Fraction ◽  
High Entropy Alloy ◽  
Induction Melting ◽  
Face Centered Cubic ◽  
Micro Hardness ◽  
Rich Phase ◽  
Σ Phase ◽  
High Entropy ◽  
Temperature Range

A bulk casting ingot (Ø70 × 150mm) of CoCrFeNiTi0.5 high entropy alloy was prepared by vacuum medium frequency induction melting. The samples from the ingot were aged for 12h in the temperature range of 900-1100°C and then quenched in water to investigate the effect of aging temperature on the microstructure and hardness of CoCrFeNiTi0.5 alloy. The crystalline structure of as-cast CoCrFeNiTi0.5 alloy consisted of the principal face-centered cubic (FCC) dendrite phase plus (Ni, Ti)-rich R phase, (Fe, Cr)-rich σ phase, (Co, Ti)-rich Laves phase within the inter-dendrite area. The dendrite contained approximately equivalent amount of Co, Cr, Fe, Ni and a smaller amount of Ti element. After aging treatment in the temperature range of 900-1000°C, the (Co, Ti)-rich phase disappeared while the amount of (Ni, Ti)-rich phase and (Fe, Cr)-rich phase increased. But the volume fraction of FCC dendrite phase increased and the intermetallic phases decreased after aging at 1100°C. The micro-hardness and the macro-hardness of the as-cast CoCrFeNiTi0.5 alloy were HV616.8 and HRC52, respectively. After heat treatment at 1000°C, the micro-hardness and macro-hardness decreased from HV616.8 to HV386.8 and from HRC52 to HRC42.7, respectively.

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.

scholarly journals Influence of Titanium on Microstructure, Phase Formation and Wear Behaviour of AlCoCrFeNiTix High-Entropy Alloy

Entropy ◽  
2018 ◽  
Vol 20 (7) ◽  
pp. 505 ◽  
Author(s):  
Martin Löbel ◽  
Thomas Lindner ◽  
Thomas Mehner ◽  
Thomas Lampke
Keyword(s):  
Phase Formation ◽  
Wear Behaviour ◽  
High Entropy Alloy ◽  
High Entropy

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.

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 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.

Sign in / Sign up

Export Citation Format

Share Document