Effects of Transient Thermal Shock on the Microstructure and Mechanical Properties of CoCrFeNiMn High-Entropy Alloy Coatings

CoCrFeNiMn high-entropy alloy (HEA) has great potential for engineering application due to its good ductility and high fracture toughness at low temperature. It can be deposited on components as coatings to take advantage of its excellent properties and reduce the cost. In this study, CoCrFeNiMn HEA coatings were deposited on 316L stainless steel substrates by atmospheric plasma spraying (APS) technique, and a series of transient thermal shock tests were performed. It was found that the coatings contained two main phases: a face-centered cubic (FCC) solid solution phase and a flocculent oxides phase. The elemental contents of Co, Cr, Fe, and Ni were close to equal atomic percentage in the coating, while Mn was reduced significantly. The oxygen was mainly distributed in the dark flocculent oxides phase. After transient thermal shock tests, these two phases remained stable, but some tiny cracks appeared on the surface. Meanwhile, the microhardness of the coating after transient thermal shock tests also showed stable, ∼ 420 HV. Weibull statistics were used to analyze the reliability of the microhardness, and the Weibull modulus m was distributed from 9 to 15. The CoCrFeNiMn HEA coating exhibited high phase stability and excellent properties under transient thermal shock, making it have service advantages in extreme environments, especially in the fields of the development of future nuclear and aerospace structural materials.

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Microstructures and Tribological Properties of TiC Reinforced FeCoNiCuAl High-Entropy Alloy at Normal and Elevated Temperature

Metals ◽

10.3390/met10030387 ◽

2020 ◽

Vol 10 (3) ◽

pp. 387 ◽

Cited By ~ 2

Author(s):

Tie Zhu ◽

Hong Wu ◽

Rui Zhou ◽

Ningyi Zhang ◽

Yong Yin ◽

...

Keyword(s):

Friction Coefficient ◽

Room Temperature ◽

High Fracture Toughness ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Fracture ◽

Microscopy Imaging ◽

High Entropy ◽

High Temperature Mechanical Properties ◽

Abrasive Behavior

Recent studies have suggested that high-entropy alloys (HEAs) possess high fracture toughness, good wear resistance, and excellent high-temperature mechanical properties. In order to further improve their properties, a batch of TiC-reinforced FeCoNiCuAl HEA composites were fabricated by mechanical alloying and spark plasma sintering. X-ray diffractometry analysis of the TiC-reinforced HEA composites, combined with scanning electron microscopy imaging, indicated that TiC particles were uniformly distributed in the face-centered cubic and body-centered cubic phases. The room temperature hardness of the FeCoNiCuAl HEA was increased from 467 to 768 HV with the addition of TiC, owing to precipitation strengthening and fine grain strengthening effects. As the TiC content increased, the friction coefficient of the FeCoNiCuAl HEA first increased and then decreased at room temperature, due to the transition of the wear mechanism from adhesive to abrasive behavior. At higher temperature, the friction coefficient of the FeCoNiCuAl HEA monotonously reduced, corresponding well with the transition from adhesive wear to oxidative wear.

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Preparation of a Light-Weight MgCaAlLiCu High-Entropy Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.727.132 ◽

2017 ◽

Vol 727 ◽

pp. 132-135 ◽

Cited By ~ 6

Author(s):

Xing Hao Du ◽

Rui Wang ◽

Cai Chen ◽

Bao Lin Wu ◽

J.C. Huang

Keyword(s):

Solid Solution ◽

Tetragonal Symmetry ◽

High Entropy Alloy ◽

Solid Solution Phase ◽

Light Weight ◽

High Fracture ◽

Compression Process ◽

High Entropy ◽

Symmetry Structure ◽

Alloy Cast

In this paper, a light-weight equimolar MgCaAlLiCu high entropy alloy (HEA) is reported. The microstructure of the alloy cast in copper mould was composed mainly of a solid solution phase with tetragonal symmetry structure, presenting the high-entropy alloy nature. The alloy exhibited high fracture strength of 910 MPa during the room-temperature compression process. Based on thermodynamic calculation, the underlying reason for the formation of the solid solution in the MgCaAlLiCu alloy is given.

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Microstructure and Properties of CoCrFeNi(WC) High-Entropy Alloy Coatings Prepared Using Mechanical Alloying and Hot Pressing Sintering

Coatings ◽

10.3390/coatings9010016 ◽

2018 ◽

Vol 9 (1) ◽

pp. 16 ◽

Cited By ~ 2

Author(s):

Juan Xu ◽

Shouren Wang ◽

Caiyun Shang ◽

Shifeng Huang ◽

Yan Wang

Keyword(s):

Wear Resistance ◽

Corrosion Resistance ◽

Mechanical Alloying ◽

Hot Pressing ◽

High Entropy Alloy ◽

Solid Solution Phase ◽

Second Phase ◽

Face Centered Cubic ◽

High Entropy ◽

Hot Pressing Sintering

The CoCrFeNi high-entropy alloy coatings (HEACs) with different weight ratios (10 and 30 wt.%) of WC additions have been prepared using mechanical alloying and a vacuum hot pressing sintering technique on a Q235 steel substrate. The microstructures, microhardness, wear resistance, and corrosion resistance of HEACs were studied. The CoCrFeNi(WC) powders were obtained by mixing the CoCrFeNi HEA powders and WC particles. The sintered products of both HEACs with high relative density contained one solid solution phase with face-centered cubic structure, WC, and unknown precipitate phases. The transition boundary had a good metallurgical bonding with the coating and substrate. The average microhardness values of CoCrFeNi HEACs with 10 and 30 wt.% WC additions reached 475 and 531 HV respectively, which were far higher than that of the substrate (160 HV). Moreover, both coatings exhibited better wear resistance than the substrate under the same wear conditions. The 30 wt.% WC HEAC displayed the lower friction coefficient, and the shallower wear groove depth. The grain refinement strengthening and second-phase particle strengthening could be beneficial to the enhanced hardness and wear resistance of coatings with WC additions. The corrosion behavior of the tested samples in the 3.5 wt.% NaCl solution were investigated using electrochemical polarization measurements. The CoCrFeNi(WC) coatings all revealed the improved corrosion resistance. Especially, a 10 wt.% WC addition remarkably enhanced the comprehensive corrosion resistance and easy passivation of CoCrFeNi HEAC.

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Microstructure and Mechanical Properties Investigation of the CoCrFeNiNbx High Entropy Alloy Coatings

Crystals ◽

10.3390/cryst8110409 ◽

2018 ◽

Vol 8 (11) ◽

pp. 409 ◽

Cited By ~ 7

Author(s):

Hui Jiang ◽

Kaiming Han ◽

Dayan Li ◽

Zhiqiang Cao

Keyword(s):

Wear Resistance ◽

Steel Substrate ◽

Alloy Coating ◽

304 Stainless Steel ◽

Molar Ratio ◽

High Entropy Alloy ◽

Solid Solution Phase ◽

Face Centered Cubic ◽

Laves Phases ◽

High Entropy

In this work, the CoCrFeNiNbx (x: molar ratio, x = 0.45, 0.5, 0.75, and 1.0) high entropy alloy coatings were synthesized on a 304 stainless steel substrate by laser cladding to investigate the effect of Nb element on their microstructure, hardness, and wear resistance. The results indicated that in all of the CoCrFeNiNbx alloy coatings, two phases were found: One was a face-centered cubic (FCC) solid solution phase, the other was a Co1.92Nb1.08-type Laves phase. The microstructures of samples varied from hypoeutectic structure (x = 0.45 and 0.5) to hypereutectic structure (x = 0.75 and 1.0). The Vickers hardness of CoCrFeNiNbx alloy coatings was obviously improved compared with the substrate. The hardness value of the CoCrFeNiNb1.0 alloy coating reached to 590 HV, which was 2.8 times higher than that of the substrate. There was also a corresponding variation in wear properties with hardness evolutions. Wherein the hypereutectic CoCrFeNiNb1.0 alloy coating with the highest hardness exhibited the best wear resistance under the same wear condition, the dry wear test showed the wear mass loss of CoCrFeNiNb1.0 alloy coating was less than a third of the substrate. The high hardness and wear resistance properties were considered with the fine lamellar eutectic structure and proper combination of FCC and Laves phases.

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TENSILE AND COMPRESSIVE MECHANICAL BEHAVIOR OF A CoCrCuFeNiAl0.5 HIGH ENTROPY ALLOY

International Journal of Modern Physics B ◽

10.1142/s0217979209060774 ◽

2009 ◽

Vol 23 (06n07) ◽

pp. 1254-1259 ◽

Cited By ~ 53

Author(s):

FANGJUN WANG ◽

YONG ZHANG ◽

GUOLIANG CHEN ◽

HYWEL A. DAVIES

Keyword(s):

Solid Solution ◽

Solution Phase ◽

High Entropy Alloy ◽

Solid Solution Phase ◽

Face Centered Cubic ◽

Compressive Properties ◽

Large Plastic Strain ◽

High Entropy ◽

Strain Limit ◽

Face Centered

A high entropy alloy of composition CoCrCuFeNiAl 0.5 is mainly composed of a face centered cubic (FCC) solid solution phase. The tensile and compressive properties of the alloy were investigated; the alloy exhibited a tensile strength of 707 MPa, together with a large plastic strain limit of 19%.

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Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽

10.3390/met9030345 ◽

2019 ◽

Vol 9 (3) ◽

pp. 345 ◽

Cited By ~ 3

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.

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Vacuum brazing of Al2O3 and 3D printed Ti6Al4V lap-joints using high entropy driven AlZnCuFeSi filler

Scientific Reports ◽

10.1038/s41598-021-87705-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ashutosh Sharma ◽

Byungmin Ahn

Keyword(s):

Strength Properties ◽

Lap Joints ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Plasma Sintering ◽

Spark Plasma ◽

3D Printed ◽

Face Centered ◽

Alloy Filler

AbstractIn this work, we studied the brazing characteristics of Al2O3 and 3D printed Ti–6Al–4V alloys using a novel equiatomic AlZnCuFeSi high entropy alloy filler (HEAF). The HEAF was prepared by mechanical alloying of the constituent powder and spark plasma sintering (SPS) approach. The filler microstructure, wettability and melting point were investigated. The mechanical and joint strength properties were also evaluated. The results showed that the developed AlZnCuFeSi HEAF consists of a dual phase (Cu–Zn, face-centered cubic (FCC)) and Al–Fe–Si rich (base centered cubic, BCC) phases. The phase structure of the (Cu–Al + Ti–Fe–Si)/solid solution promises a robust joint between Al2O3 and Ti–6Al–4V. In addition, the joint interfacial reaction was found to be modulated by the brazing temperature and time because of the altered activity of Ti and Zn. The optimum shear strength reached 84 MPa when the joint was brazed at 1050 °C for 60 s. The results can be promising for the integration of completely different materials using the entropy driven fillers developed in this study.

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Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

Metals ◽

10.3390/met11050742 ◽

2021 ◽

Vol 11 (5) ◽

pp. 742

Author(s):

Motomichi Koyama ◽

Takeaki Gondo ◽

Kaneaki Tsuzaki

Keyword(s):

Low Temperature ◽

Plastic Anisotropy ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Microstructure Refinement ◽

Hexagonal Close Packed ◽

Solution Treated Condition ◽

Solution Treated ◽

Face Centered

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

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Influence of V and Heat Treatment on Characteristics of WMoNbTaV Refractory High-Entropy Alloy Coatings by Mechanical Alloying

Coatings ◽

10.3390/coatings11030265 ◽

2021 ◽

Vol 11 (3) ◽

pp. 265

Author(s):

Chun-Liang Chen ◽

Sutrisna

Keyword(s):

Heat Treatment ◽

Mechanical Alloying ◽

Annealing Treatment ◽

High Energy ◽

304 Stainless Steel ◽

Homogeneous Distribution ◽

High Entropy Alloy ◽

Solid Solution Phase ◽

High Entropy ◽

Steel Substrates

Refractory high-entropy alloy (RHEA) is one of the most promising materials for use in high-temperature structural materials. In this study, the WMoNbTaV coatings on 304 stainless steel substrates has been prepared by mechanical alloying (MA). Effects of V addition and subsequent heat treatment on properties of the WMoNbTaV coatings were investigated. The results show that the RHEA coatings with nanocrystalline body-centered cubic (BCC) solid-solution phase were generated by the mechanical alloying process. The presence of the V element promotes a uniform microstructure and homogeneous distribution of composition in the RHEA coatings due to improving alloying efficiency, resulting in an increase of hardness. After the annealing treatment of the RHEA coatings, microstructure homogeneity was further enhanced; however, the high affinity of Ta for oxygen causes the formation of Ta-rich oxides. Annealing also removes strain hardening generated by high-energy ball milling and thus decreases the hardness of the RHEA coating and alters microstructure evolution and mechanical properties.

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Influence of Aluminum and Molybdenum on the Microstructure and Corrosion Behavior of Thermally Sprayed High-Entropy Alloy Coatings

Journal of Thermal Spray Technology ◽

10.1007/s11666-021-01297-6 ◽

2021 ◽

Author(s):

Martin Löbel ◽

Thomas Lindner ◽

Maximilian Grimm ◽

Lisa-Marie Rymer ◽

Thomas Lampke

Keyword(s):

Corrosion Resistance ◽

Protective Coatings ◽

Base Alloy ◽

Alloy System ◽

High Entropy Alloy ◽

Oxide Content ◽

Face Centered Cubic ◽

High Entropy ◽

Structural And Functional Properties ◽

Wide Range

AbstractHigh-entropy alloys (HEAs) have shown a wide range of promising structural and functional properties. By the application of coating technology, an economical exploitation can be achieved. The high wear and corrosion resistance of HEAs make them particularly interesting for the application as protective coatings. Especially for alloys with a high chromium content, a high corrosion resistance has been revealed. For the current investigations, the equimolar HEA CrFeCoNi with a single-phase face centered cubic structure is considered as a base alloy system. To increase the corrosion resistance as well as the hardness and strength, the influence of the alloying elements aluminum and molybdenum is analyzed. For the current investigations, the high kinetic process high-velocity oxygen fuel thermal spraying (HVOF) has been considered to produce coatings with a low porosity and oxide content. Feedstock is produced by inert gas atomization. The influence of the alloy composition on the microstructure, phase formation and resulting property profile is studied in detail. A detailed analysis of the corrosion resistance and underlying mechanisms is conducted. The pitting and passivation behavior are investigated by potentiodynamic polarization measurements in NaCl and H2SO4 electrolyte. A distinct improvement of the corrosion resistance can be achieved for the alloy Al0.3CrFeCoNiMo0.2.

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