scholarly journals Interfacial Microstructure of FeCoNiCrAl0.1 High Entropy Alloy and Pure Copper Prepared by Explosive Welding

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1197
Author(s):  
Qichao Tian ◽  
Hanliang Liang ◽  
Yang Zhao ◽  
Honghao Ma ◽  
Zhaowu Shen ◽  
...  
Keyword(s):  
Explosive Welding ◽  
Pure Copper ◽  
Composite Plates ◽  
Interfacial Microstructure ◽  
Grain Structure ◽  
High Entropy Alloy ◽  
Elemental Distribution ◽  
Electron Backscattered Diffraction ◽  
High Entropy ◽  
Vortex Zone

The FeCoNiCrAl0.1 high entropy alloys (HEAs) and pure copper (Cu) composite plates were successfully fabricated by the explosive welding technique using two different gap distances. The interfacial microstructure, elemental distribution, grain structure of vortex zone and hardness were characterized using optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), nanoindentation and micro-hardness tester. The explosive weldability window was calculated to verify the weldability of HEAs and Cu. The results indicated that the Cu/HEA composites presented typical wavy structures without visible defects and have an excellent bonding quality. The elements mixed and formed intermetallic compounds at the vortex zones. The grains near the vortex zones showed strong deformation, and phase transformation occurred. Compared with the matrix metals, the hardness of Cu and HEAs increased near the welding interface and sharply increased to 375 HV near the vortex zone.

On the low cycle fatigue response of CoCrNiFeMn high entropy alloy with ultra-fine grain structure

2021 ◽  
Vol 205 ◽  
pp. 116540
Author(s):  
S. Picak ◽  
T. Wegener ◽  
S.V. Sajadifar ◽  
C. Sobrero ◽  
J. Richter ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Grain Structure ◽  
High Entropy Alloy ◽  
Cycle Fatigue ◽  
High Entropy ◽  
Fine Grain

Development of a Refractory Hexagonal Closed Packed High Entropy Alloy Based on Thin Film Screening

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1435-1440
Author(s):  
Azin Akbari ◽  
T. John Balk
Keyword(s):  
Thin Film ◽  
Single Phase ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
High Entropy Alloy ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
High Entropy ◽  
Si Substrates ◽  
Hexagonal Closed Packed

In order to identify candidate high entropy alloys (HEAs) that have the hexagonal closed packed crystal structure, gradient thin films in the OsRuWMoRe system were deposited by sputtering from multiple elemental targets onto Si substrates. In addition to having compositional gradients, the films exhibited regions with different phases, some of which were single-phase and non-equiatomic. Such alloys have the potential to exhibit properties superior to the primarily equiatomic HEAs that have been the focus of most work in this area. To screen the phases that exist across the thin film gradient samples, a range of characterization techniques were employed, including focused ion beam and scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray diffraction and electron backscattered diffraction analysis. The combinatorial method described in this study enabled the identification of a candidate single-phase HEA that was subsequently fabricated as a bulk alloy.

scholarly journals Effect of Enhanced Gravity on the Microstructure and Mechanical Properties of Al0.9CoCrFeNi High-Entropy Alloy

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1318
Author(s):  
Anjun Shi ◽  
Ruixuan Li ◽  
Yong Zhang ◽  
Zhe Wang ◽  
Zhancheng Guo
Keyword(s):  
Mechanical Properties ◽  
The Body ◽  
Grain Structure ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Microstructure And Mechanical Properties ◽  
Gravity Fields ◽  
Bcc Structure ◽  
Strength And Plasticity ◽  
Gravity Acceleration

The influence of enhanced gravity on the microstructure and mechanical properties of the Al0.9CoCrFeNi high-entropy alloy, which was solidified under normal gravity (acceleration 1 g) and enhanced gravity (acceleration 140 g, acceleration 210 g, and acceleration 360 g) conditions is reported in this paper. Its solidification under enhanced gravity fields resulted in refinement of the columnar nondendritic grain structure and an increase in the area fraction of the body-centered cubic (BCC) structure phases. The mass transfer strengthened by enhanced gravity promoted element diffusion and enrichment, which caused changes in the composition and microstructure that, in turn, affected the mechanical properties of the alloy. The compressive strength and plasticity of the sample solidified at acceleration 360 g were equal to 2845 MPa and 36.4%, respectively, which are the highest values reported to date for Al0.9CoCrFeNi alloy.

scholarly journals QUANTITATIVE CHARACTERIZATION OF MICROSTRUCTURE OF PURE COPPER PROCESSED BY ECAP

2013 ◽  
Vol 32 (2) ◽  
pp. 65 ◽  
Author(s):  
Ondřej Šedivý ◽  
Viktor Beneš ◽  
Petr Ponížil ◽  
Petr Král ◽  
Václav Sklenička
Keyword(s):  
Structural Parameters ◽  
Pure Copper ◽  
Orientation Imaging Microscopy ◽  
Grain Morphology ◽  
Grain Structure ◽  
Boundary Structure ◽  
Electron Backscattered Diffraction ◽  
Quantitative Characterization ◽  
Grain Boundary Structure

Orientation imaging microscopy (OIM) allows to measure crystallic orientations at the surface of the material. Digitalized data representing the orientations are processed to recognize the grain structure and they are visualized in crystal orientation maps. Analysis of the data firstly consists in recognition of grain boundaries followed by identification of grains themselves. Knowing the grain morphology it is possible to characterize the homogeneity of the structure and estimate structural parameters related to the physical properties of the material. The paper describes methods of imaging and quantitative characterization of the grain boundary structure in metals based on data from electron backscattered diffraction (EBSD).

In-situ formed heterogeneous grain structure in spark-plasma-sintered CoCrFeMnNi high-entropy alloy overcomes the strength-ductility trade-off

2020 ◽  
Vol 771 ◽  
pp. 138625 ◽  
Author(s):  
Feilong Jiang ◽  
Cancan Zhao ◽  
Dingshan Liang ◽  
Weiwei Zhu ◽  
Yiwen Zhang ◽  
...  
Keyword(s):  
Grain Structure ◽  
High Entropy Alloy ◽  
Trade Off ◽  
High Entropy ◽  
Spark Plasma

scholarly journals Laser-generated high entropy metallic glass nanoparticles as bifunctional electrocatalysts

Nano Research ◽  
2021 ◽  
Author(s):  
Jacob Johny ◽  
Yao Li ◽  
Marius Kamp ◽  
Oleg Prymak ◽  
Shun-Xing Liang ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Energy Conversion ◽  
Photoelectron Spectroscopy ◽  
Surface Segregation ◽  
Amorphous Structure ◽  
High Entropy Alloy ◽  
Elemental Distribution ◽  
X Ray ◽  
High Entropy ◽  
Depth Analysis

AbstractHigh entropy metallic glass nanoparticles (HEMG NPs) are very promising materials for energy conversion due to the wide tuning possibilities of electrochemical potentials offered by their multimetallic character combined with an amorphous structure. Up until now, the generation of these HEMG NPs involved tedious synthesis procedures where the generated particles were only available on highly specialized supports, which limited their widespread use. Hence, more flexible synthetic approaches to obtain colloidal HEMG NPs for applications in energy conversion and storage are highly desirable. We utilized pulsed laser ablation of bulk high entropy alloy targets in acetonitrile to generate colloidal carbon-coated CrCoFeNiMn and CrCoFeNiMnMo HEMG NPs. An in-depth analysis of the structure and elemental distribution of the obtained nanoparticles down to single-particle levels using advanced transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) methods revealed amorphous quinary and senary alloy phases with slight manganese oxide/hydroxide surface segregation, which were stabilized within graphitic shells. Studies on the catalytic activity of the corresponding carbon-HEMG NPs during oxygen evolution and oxygen reduction reactions revealed an elevated activity upon the incorporation of moderate amounts of Mo into the amorphous alloy, probably due to the defect generation by atomic size mismatch. Furthermore, we demonstrate the superiority of these carbon-HEMG NPs over their crystalline analogies and highlight the suitability of these amorphous multi-elemental NPs in electrocatalytic energy conversion.

scholarly journals Corrosion Behavior of Selectively Laser Melted CoCrFeMnNi High Entropy Alloy

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1029 ◽  
Author(s):  
Jie Ren ◽  
Chaitanya Mahajan ◽  
Liang Liu ◽  
David Follette ◽  
Wen Chen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Laser Processing ◽  
Electrochemical Impedance ◽  
Processing Parameters ◽  
High Entropy Alloy ◽  
Elemental Distribution ◽  
Powder Bed ◽  
High Entropy ◽  
Wide Range ◽  
Superior Corrosion Resistance

CoCrFeMnNi high entropy alloys (HEAs) were additively manufactured (AM) by laser powder bed fusion and their corrosion resistance in 3.5 wt% NaCl solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests. A systematic study of AM CoCrFeMnNi HEAs’ porosity under a wide range of laser processing parameters was conducted and a processing map was constructed to identify the optimal laser processing window for CoCrFeMnNi HEAs. The near fully dense AM CoCrFeMnNi HEAs exhibit a unique non-equilibrium microstructure consisting of tortuous grain boundaries, sub-grain cellular structures, columnar dendrites, associated with some processing defects such as micro-pores. Compared with conventional as-cast counterpart, the AM CoCrFeMnNi HEAs showed higher pitting resistance (ΔE) and greater polarization resistance (Rp). The superior corrosion resistance of AM CoCrFeMnNi HEAs may be attributed to the homogeneous elemental distribution and lower density of micro-pores. Our study widens the toolbox to manufacture HEAs with exceptional corrosion resistance by additive manufacturing.

scholarly journals Microstructure and Shear Strength of Brazing High Entropy TiZrHfNbMo Alloy and Si3N4 Ceramics Joints

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 472
Author(s):  
Xiaohong Wang ◽  
Duo Dong ◽  
Xiaohong Yang ◽  
Peng Huang ◽  
Kangqiao Shi ◽  
...  
Keyword(s):  
Solid Solution ◽  
Shear Strength ◽  
Intermetallic Compounds ◽  
Reaction Layer ◽  
Interfacial Microstructure ◽  
High Entropy Alloy ◽  
Si3n4 Ceramic ◽  
High Entropy ◽  
Brazed Joints ◽  
Brazed Joint

The effects of different brazing processes on the interfacial microstructure and shear strength of TiZrHfNbMo high-entropy alloy (HEAS) and Si3N4 ceramic brazed joints were studied. There is no obvious defect in a brazed TiZrHfNbMo HEAS/AgCuTi/Si3N4 ceramic joint, and the two materials have good metallurgical bonding. The typical interface microstructure is Si3N4/Ti5Si3/Ag solid solution +Cu (s,s)+ CuTi/Cu2Ti/Cu4Ti + TiCu(Hf,Zr)NbMo/TiZrHfNbMo HEAs. With the increase of brazing temperature, the dispersed CuTi phase agglomerates in the brazed joint, and acts as the nucleate of the Cu-based solid solution. The thickness of the reaction layer increases with the increase of phases in the reaction layer on both sides of the joint. When the brazing temperature is 800 °C, 820 °C, 840 °C and 860 °C, the shear strength of the brazed joint is 30 MPa, 72 MPa, 86 MPa and 21 MPa, respectively. The formation of CuTi and Ti5Si3 intermetallic compounds increases the thickness of the reaction layer, and improves the strength of the joint. However, excessive CuTi and Ti5Si3 intermetallic compounds lead to a significant decrease in joint strength. The grain coarsening of the joint can also affect the strength of the joint.

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