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1
Content available Tribological Studies on AlCrFeCuCoNi High Entropy Alloy Surface Coated on Ti-6Al-4V Using Plasma Transferred Arc Technique
Prabu G., Duraiselvam Muthukannan
Archives of Metallurgy and Materials
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2022
|
Vol. 67, iss. 2
409--420
EN
AlCrFeCuCoNi high entropy particles were alloyed on Ti-6Al-4V surface using Plasma transferred arc (PTA) process. PTA alloyed surfaces were investigated for their phase formation, microhardness improvement and wear behaviour. The various wear mechanism and their corresponding surface roughness were studied. The results revealed that the dual phase of BCC and FCC microstructure along with some intermetallic compounds were grown in the alloyed region through the PTA technique and good metallurgical bonding of the alloyed region with the base material were achieved. The PTA alloyed region exhibited a hardness of 718 HV0.2 which is 2.2 times higher than the hardness of base material. The PTA alloyed samples showed higher wear resistance due to the solid solution strengthening as the HEA has high entropy of mixing that leads to the reduction of free energy of the alloyed region. It exhibited better interconnection of the coated material and superior metallurgical bonding to the base material. Frictional heat produced during the wear test has promoted the formation of FeO, Cr2O3, CuO, NiO and Al2O3 oxide film on the PTA alloyed sample. These oxide films act as a barrier between two mating surfaces and improve the tribo performance of the PTA alloyed sample.
2
Content available Influence of High-Temperature Oxidizing Conditions on AlCoCrCuNi High Entropy Alloys with and without Silicon Addition
Gawel R., Rogal Ł., Przybylski K., Matsuda Kenji
Archives of Metallurgy and Materials
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2022
|
Vol. 67, iss. 2
471--478
EN
Initial investigations on oxidation behaviour and phase transformations of equimolar AlCoCrCuNi high entropy alloy with and without 1 at.% silicon addition during 24-hr exposure to air atmosphere at 1273 K was carried out in this work. After determining the oxidation kinetics of the samples by means of thermogravimetric analysis, the morphology, chemical and phase compositions of the oxidized alloys were determined by means of scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analysis. Additional cross-section studies were performed using transmission electron microscopy combined with energy dispersive X-ray spectroscopy and selected area electron diffraction. From all these investigations, it can be concluded that minor silicon addition improves the oxidation kinetics and hinders the formation of an additional FCC structure near the surface of the material.
3
Content available Impact Behavior of the Ballistic Targets Package Composed of Dyneema Polymer and High Entropy Alloy Structures
Voiculescu Ionelia, Geanta Victor, Chereches Tudor, Vizureanu Petrica, Stefanoiu Radu, Rotariu Adrian-Nicolae, Mitrica Dumitru
Archives of Metallurgy and Materials
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2022
|
Vol. 67, iss. 2
569--576
EN
Ballistic targets are multi-material assemblies that can be made of various materials, such as metal alloys, ceramics, and polymers. Their role is to provide collective or individual ballistic protection against high-speed dynamic penetrators or kinetic fragments. The paper presents the impact behavior with incendiary perforating bullets having 7.62 mm of ballistic packages made of combinations between Dyneema ultra-high-molecular-weight polyethylene and high entropy alloy from alloying system AlCoCrFeNi, by analyzing the dynamic phenomena (deformation, perforation) that take place at high speeds. The geometry evolution of the physical model subjected to numerical simulation allows a very good control over the discretization network and also allows the export for modeling to nonlinear transient phenomena. The results obtained by numerical simulation showed that the analyzed ballistic package does not allow sufficient protection for values of impact velocities over 500 m/sec.
4
Content available Friction Stir Welding/Processing of High Entropy Alloys (HEAs)
Mishra Akshansh
Welding Technology Review
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2021
|
R. 93, nr 1
27--33
EN
The composition of High Entropy Alloys is quite different from the existing classical engineering alloys because in near equiatomic ratios they contain multiple principal alloying elements. Design and development of high entropy alloys is very important to overcome the shortcomings of conventionally used alloys in applications where operating conditions of temperature and loading are extreme. High entropy alloys generally find applications in compressor blades of an aerospace engine, energy, and transportation industries due to its low density and high strength. In order to enhance the application of high entropy alloys, the proper selection of a feasible welding process is very important. It has been observed that when high entropy alloys are subjected to the welding process other than the Friction Stir Welding process then it will result in reduced overall strength and lower hardness in the fusion zone and heat-affected zone. In this recent paper, the application of Friction Stir Welding for joining the high entropy alloys and also using Friction Stir Processing for improving the mechanical and microstructure properties of high entropy alloys are discussed.
PL
Projektowanie i opracowywanie stopów o wysokiej entropii jest bardzo ważne, aby przezwyciężyć niedociągnięcia konwencjonalnie stosowanych stopów w zastosowaniach, w których warunki pracy, takie jak temperatura i obciążenie, są ekstremalne. Stopy o wysokiej entropii zwykle znajdują zastosowanie w łopatkach sprężarek silników lotniczych, energetyce i transporcie ze względu na ich niską gęstość i wysoką wytrzymałość. Aby usprawnić stosowanie stopów o wysokiej entropii, bardzo ważny jest właściwy dobór możliwego do wykonania procesu spawania. Zaobserwowano, że gdy stopy o wysokiej entropii zostaną poddane procesowi spawania innemu niż proces zgrzewania tarciowego z mieszaniem, to spowoduje to zmniejszoną ogólną wytrzymałość i niższą twardość w strefie topienia i strefie wpływu ciepła. W artykule omówiono zastosowanie zgrzewania tarciowego z przemieszaniem do łączenia stopów o wysokiej entropii, a także zastosowanie tarciowej modyfikacji z przemieszaniem do poprawy właściwości mechanicznych i mikrostrukturalnych tych stopów.
5
Content available Microstructural Evolution of AlCuFeMnTi-0.75Si High Entropy Alloy Processed by Mechanical Alloying and Spark Plasma Sintering
Kim Minsu, Sharma Ashutosh, Chae Myoung Jin, Lee Hansung, Ahn Byungmin
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 3
703--707
EN
In this work, we have designed a new high entropy alloy containing lightweight elements, e.g., Al, Fe, Mn, Ti, Cu, Si by high energy ball milling and spark plasma sintering. The composition of Si was kept at 0.75 at% in this study. The results showed that the produced AlCuFeMnTiSi0.75 high entropy alloy was BCC structured. The evolution of BCC1 and BCC2 phases was observed with increasing the milling time up to 60 h. The spark plasma sintering treatment of milled compacts from 650-950°C showed the phase separation of BCC into BCC1 and BCC2. The density and strength of these developed high entropy alloys (95-98%, and 1000 HV) improved with milling time and were maximum at 850°C sintering temperature. The current work demonstrated desirable possibilities of Al-Si based high entropy alloys for substitution of traditional cast components at intermediate temperature applications.
6
Content available Effect of Milling Duration on Oxide-Formation Behavior of Oxide-Dispersion-Strengthened High-Entropy Alloys
Song Yongwook, Kim Daeyoung, Nam Seungjin, Lee Kee-Ahn, Choi Hyunjoo
Archives of Metallurgy and Materials
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2021
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Vol. 66, iss. 3
735--740
EN
Oxide-dispersion-strengthened high-entropy alloys were produced by hot-pressing a ball-milled mixture of Y2O3 and atomized CoCrFeMnNi powder. The effect of milling duration on grain size reduction, oxide formation behavior, and the resulting mechanical properties of the alloys was studied. Both the alloy powder size and Y2O3 particle size decreased with milling time. Moreover, the alloy powder experienced severe plastic deformation, dramatically generating crystalline defects. As a result, the grain size was reduced to ~16.746 nm and in-situ second phases (e.g., MnO2 and σ phase) were formed at the defects. This increased the hardness of the alloys up to a certain level, although excessive amounts of in-situ second phases had the reverse effect.
7
Content available Selected Properties of High Entropy Alloys Based on the AlFeMnNbNiTi System
Chrzan Konrad, Cichocki Kamil, Adamczyk Piotr, Muszka Krzysztof
Journal of Applied Materials Engineering
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2020
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Vol. 60, iss. 2-3
71--80
EN
The aim of this work was to study the impact of various fabrication methods used to prepare high entropy alloys based on the AlFeMnNbNiTi system. Chemical composition was customized to ensure a solid solution structure with precipitation of the Laves phase. The three manufactured alloys were prepared by melting, but with the use of various input materials and different furnaces in protective atmospheres. After the melting process, heat treatment was carried out. Structures of obtained materials were analyzed by means of a Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) mapping. Mechanical properties were represented by Vickers hardness. In this paper, impact of the use of low purity input materials is shown, as well as differences in structure resulting from the utilization of different melting furnaces.
8
Content available Wave Absorption Property of High Entropy Alloy Fabricated by Sol-Gel Process
Yang Suwon, Kim Jeong-Gon, Jeong Kwang-Pil, Choi Jin-Hyuk
Archives of Metallurgy and Materials
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2020
|
Vol. 65, iss. 4
1277--1280
EN
In this study, the magnetic properties and wave absorption characteristics of high entropy alloys are investigated. The high entropy alloys with FeNiMnCoCu, FeNiMnZnCo, and FeNiZnCoCu compositions were synthesized by the sol-gel method. After the sol-gel process, the annealing process and hydrogen reduction process was performed. FeNiMnCoCu and FeNiZnCoCu were revealed soft magnetic property. The saturation magnetization was 12 emu/g and 36 emu/g, respectively. And The coercive force was –45 Oe and –34 Oe, respectively. The high entropy alloy with these compositions was revealed wave absorption property at above 10 gigahertz frequency region. And it has shown the trend that wave absorption frequency has decreased with the sample thickness increasing.
9
Content available Microstructure and Mechanical Properties of Equiatomic and Non-Equiatomic TiMoTaNbV High Entropy Alloys Prepared Using Vacuum Arc Remelting
Lee Seongi, Lee Kwangmin
Archives of Metallurgy and Materials
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2020
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Vol. 65, iss. 4
1311--1315
EN
This study investigates the microstructures and the mechanical properties of equiatomic Ti20 Mo20 Ta20 Nb20 V20 and non-equiatomic Ti40 Mo15 Ta15 Nb15 V15 and Ti60 Mo10 Ta10 Nb10 V10 HEAs using X-ray diffraction (XRD) analysis, field emission scanning electron microscope (FE-SEM), and micro-Vickers hardness test. The specimens were fabricated using the vacuum arc remelting (VAR) process and homogenized at a temperature of 1300°C for 4 h in a vacuum atmosphere. The determined thermodynamic parameters, Ω ≥ 1.1, δ ≤ 6.6%, and VEC < 6.87, suggested that the HEAs consisted of BCC solid solutions. XRD patterns of all the HEAs displayed single BCC phases. The difference in the solidification rate led to the micro-segregation associated with the elements Ta and Mo enriched in the dendrite arms and the elements V and Ti in the inter-dendritic regions. The HEA specimens showed a decrease in hardness with higher concentration of Ti element because the intrinsic hardness of Ti is lower as compared to the intrinsic hardness of Nb and Mo.
10
Content available Microstructure and Electrochemical Behaviors of Equiatomic TiMoVCrZr and Ti-rich TiMoVCrZr High-Entropy Alloys for Metallic Biomaterials
Song Hocheol, Lee Seongi, Lee Kwangmin
Archives of Metallurgy and Materials
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2020
|
Vol. 65, iss. 4
1317--1322
EN
The present study investigated various thermodynamic parameters, microstructures and electrochemical behaviors of TiMoVCrZr and Ti-rich TiMoVCrZr high-entropy alloys (HEAs) prepared by vacuum arc remelting. The microstructures of the alloys were analyzed using X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), and potentiodynamic polarization tests. The determined thermodynamic values of the Ω-parameter and the atomic size difference (δ) for the HEAs were determined to be in the range of Ω ≥ 1.1, and δ ≤ 6.6% with valance electron configuration (VEC) ≤ 5.0, suggesting the HEAs were effective at forming solid solutions. XRD patterns of the equiatomic Ti20 Mo20 V20 Cr20 Zr20 HEA revealed four phases consisting of the body centered cubic1 (BCC1 ), BCC2 , hexagonal close-packed (HCP), and intermetallic compound Cr2 Zr phases. Three phases were observed in the XRD patterns of Ti-rich Ti40 Mo15 V15 Cr15 Zr15 (BCC, HCP, and Cr2 Zr) and a single BCC phase was observed in Ti-rich Ti60 Mo10 V10 Cr10 Zr10 HEAs. The backscattered-electron (BSE) images on the equiatomic Ti20 Mo20 V20 Cr20 Zr20 HEA revealed BCC and HCP phases with Cr2 Zr precipitates, suggesting precipitation from the HCP solid solution during the cooling. The micro-segregation of Ti-rich Ti60 Mo10 V10 Cr10 Zr10 HEAs appeared to decrease remarkably. The alloying elements in the HEAs were locally present and no phase changes occurred even after additional HIP treatment. The lowest current density obtained in the polarization potential test of Ti-rich Ti40 Mo15 V15 Cr15 Zr15 HEA was 7.12×10-4 mA/cm2 was obtained. The studied TiMoVCrZr HEAs showed improved corrosion characteristics as compared to currently available joint replacement material such as ASTM F75 alloy.
11
Content available Microstructure of Multi-Component Ni35Ti35Ta10Co10Cu10 Alloy
Glowka K., Zubko M., Świec P., Prusik K., Dercz G., Matyja E., Stróż D.
Archives of Metallurgy and Materials
|
2019
|
Vol. 64, iss. 2
715--719
EN
A new NiTi-based multi-component Ni35 Ti35 Ta10 Co10 Cu10 (at.%) alloy was obtained by vacuum arc melting. The microstructure of the alloy has been studied using scanning and transmission electron microscopy, backscatter electron diffraction and X-ray diffraction techniques. The performed measurements showed presence of two cubic and one tetragonal phases. Energy dispersive X-ray spectroscopy analysis confirmed that all the observed phases contained all five principal elements.
12
Content available Microstructure Analysis of Equiatomic Multi-Component Ni20Ti20Ta20Co20Cu20 Alloy
Glowka K., Zubko M., Świec P., Prusik K., Dercz G., Stróż D.
Archives of Metallurgy and Materials
|
2019
|
Vol. 64, iss. 2
785--789
EN
An equiatomic multi-component alloy Ni20Ti20Ta20Co20Cu20 (at.%) was obtained using vacuum arc melting. In order to characterize such an alloy, microstructure analysis has been performed using Scanning and Transmission Electron Microscopy, Electron Backscattered Diffraction, X-ray Diffraction and Energy Dispersive X-ray Spectroscopy techniques. Microstructure analysis revealed the presence of one rhombohedral and two cubic phases. Energy Dispersive X-ray Spectroscopy measurements revealed that both observed phases include five chemical elements in the structure. Using Rietveld refinement approach the lattice parameters were refined for the observed phases.
13
Projektowanie stopów o wysokiej entropii
Lachowska M., Gradoń P., Piątkowski J.
Rudy i Metale Nieżelazne Recykling
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2018
|
R. 63, nr 10
3--7
PL
Artykuł przedstawia przegląd rozwoju strategii i metod używanych w badaniach na temat stopów o wysokiej entropii. Jest to nowa grupa materiałów, która może być scharakteryzowana poprzez nowoczesne podejście do kompozycji stopowych. Podczas, gdy w tradycyjnych stopach można wyróżnić jeden lub dwa podstawowe elementy, których stężenie jest bardzo wysokie w stosunku do innych pierwiastków stopowych, w stopach o wysokiej entropii pięć lub więcej pierwiastków stopowych dodaje się w równych lub prawie równych proporcjach. Od dawna uważano, że ten rodzaj kompozycji doprowadzi do kruchej konglomeracji związków międzymetalicznych, ale stwierdzono, że wysoka entropia losowych stałych roztworów może je uprzywilejowywać względem innych uporządkowanych, fazowych lub międzymetalicznych związków, prowadząc do prostej jednofazowej struktury. To odkrycie stworzyło nowe, ogromne możliwości projektowania nowych materiałów, ale także konieczność przyjrzenia się istniejącym metodologiom rozwoju stopów.
EN
Paper presents a review of development strategies and methods used in research on high entropy alloys. This is a new group of materials which can be characterised by novel approach to alloy composition. Whereas in traditional alloys we can distinguish one or two base elements whose concentration is very high in relation to other alloying elements, in high entropy alloys five or more alloying elements are added in equal or near equal proportions. It has been long thought that this type of composition will lead to brittle conglomeration of intermetallics, but it was found that high entropy of random solid solutions can preferentiate them over other, ordered, phases or intermetallic compounds leading to simple single phase structure. This discovery created new and vast possibilities for designing new materials, but also necessitated revision of existing methodologies for alloy development.
14
Content available Fabrication and Characterization of CoCrFeNiMn High Entropy Alloy Powder Processed by Gas Atomization
Park T. G., Lee S. H., Lee B., Cho H. M., Choi W. J., Kim B. S., Shin K. S., Kim T.-S.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 2
1055--1059
EN
In this study, precisely controlled large scale gas atomization process was applied to produce spherical and uniform shaped high entropy alloy powder. The gas atomization process was carried out to fabricate CoCrFeNiMn alloy, which was studied for high ductility and mechanical properties at low temperatures. It was confirmed that the mass scale, single phase, equiatomic, and high purity spherical high entropy alloy powder was produced by gas atomization process. The powder was sintered by spark plasma sintering process with various sintering conditions, and mechanical properties were characterized. Through this research, we have developed a mass production process of high quality and spherical high entropy alloy powder, and it is expected to expand applications of this high entropy alloy into fields such as powder injection molding and 3D printing for complex shaped components.
15
Content available remote Synthesis and characterization of high entropy alloy (CrMnFeNiCu) reinforced AA6061 aluminium matrix composite
Prabakaran R. K., Naveen Sait A., Senthilkumar V.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 4
823--832
EN
Quinary High Entropy Alloy (HEA) system consists of Cr-Mn-Fe-Ni-Cu elements were prepared though powder metallurgy route. With varying wt. % of above prepared HEA powder as reinforcements, two different (10% and 20%) A6061 aluminium matrix composites were produced. Sinterablity of the composite powders was evaluated with different sintering time and temperature. The XRD results of HEA confirmed that the solid solution possess both FCC and BCC phases. Density, hardness and compressive strength of the fabricated composite were measured to evaluate the effect of HEA reinforcement. SEM micrographs of the composites were evaluated for the structure and to find the distribution of reinforcement particles.
16
Content available remote Synthesis and characteristization of high entropy alloy (CrMnFeNiCu) reinforced AA6061 aluminium matrix composite
Prabakaran R. K., Naveen Sait A., Senthilkumar V.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 2
415--424
EN
Quinary High Entropy Alloy (HEA) system consists of Cr-Mn-Fe-Ni-Cu elements were prepared though powder metallurgy route. With varying wt. % of above prepared HEA powder as reinforcements, two different (10% and 20%) A6061 aluminium matrix composites were produced. Sinterablity of the composite powders was evaluated with different sintering time and temperature. The XRD results of HEA confirmed that the solid solution possess both FCC and BCC phases. Density, hardness and compressive strength of the fabricated composite were measured to evaluate the effect of HEA reinforcement. SEM micrographs of the composites were evaluated for the structure and to find the distribution of reinforcement particles.
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