scholarly journals Fabrication of AlCoCrFeNi High-Entropy Alloy Coating on an AISI 304 Substrate via a CoFe2Ni Intermediate Layer

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 2 ◽  
Author(s):  
Wenyuan Cui ◽  
Sreekar Karnati ◽  
Xinchang Zhang ◽  
Elizabeth Burns ◽  
Frank Liou
Keyword(s):  
Intermediate Layer ◽  
Steel Substrate ◽  
Alloy Coating ◽  
304 Stainless Steel ◽  
High Entropy Alloy ◽  
Intermediate Step ◽  
Dendritic Microstructure ◽  
Aisi 304 ◽  
High Entropy ◽  
Average Hardness

Through laser metal deposition, attempts were made to coat AlCoCrFeNi, a high-entropy alloy (HEA), on an AISI 304 stainless steel substrate to integrate their properties. However, the direct coating of the AlCoCrFeNi HEA on the AISI 304 substrate was found to be unviable due to cracks at the interface between these two materials. The difference in compositional change was suspected to be the source of the cracks. Therefore, a new transition route was performed by coating an intermediate layer of CoFe2Ni on the AISI 304 substrate. Investigations into the microstructure, phase composition, elemental composition and Vickers hardness were carried out in this study. Consistent metallurgical bonding was observed along both of the interfaces. It was found that the AlCoCrFeNi alloy solidified into a dendritic microstructure. The X-ray diffraction pattern revealed a transition of the crystal structure of the AISI 304 substrate to the AlCoCrFeNi HEA. An intermediate step in hardness was observed between the AISI 304 substrate and the AlCoCrFeNi HEA. The AlCoCrFeNi alloy fabricated was found to have an average hardness of 418 HV, while the CoFe2Ni intermediate layer had an average hardness of 275 HV.

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

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 409 ◽  
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.

Fabrication of in-situ TiN ceramic particle reinforced high entropy alloy composite coatings by laser cladding processing

2021 ◽  
pp. 1-22
Author(s):  
Xinhong Wang ◽  
S. S. Liu ◽  
G. L. Zhao ◽  
M. Zhang
Keyword(s):  
Laser Cladding ◽  
Phase Structure ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Ceramic Particle ◽  
304 Stainless Steel ◽  
High Entropy Alloy ◽  
Laves Phases ◽  
High Entropy

Abstract In-situ TiN ceramic particle reinforced FeCoNiCrMnTi high entropy alloy coating was fabricated by laser cladding processing at high purity nitrogen gas atmosphere on the AISI 304 stainless steel substrate. The effect of Ti addition on the microstructure, phase structure and wear properties of the coatings were investigated. The results showed that phase structure of the coatings were mainly FCC-type γ phase. A few of cubic or flower-like TiN ceramic were formed after adding titanium into the FeCoNiCrMn powder. When atomic ratio of Ti exceeds 0.5, Laves phases appeared in the coatings. With increasing of Ti, the micro-hardness and wear resistance of the coatings increased, but friction coefficient and crack resistance of the coatings reduced. Suitable Ti content in the FeCoNiCrMnTix, laser composite coating had higher resistance to adhesive wear, oxidation wear and cracking resistance.

scholarly journals Microstructure and Corrosion Behavior of (CoCrFeNi)95Nb5 High-Entropy Alloy Coating Fabricated by Plasma Spraying

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 694 ◽  
Author(s):  
Wenrui Wang ◽  
Wu Qi ◽  
Lu Xie ◽  
Xiao Yang ◽  
Jiangtao Li ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Steel Substrate ◽  
Alloy Coating ◽  
High Entropy Alloy ◽  
Pitting Potential ◽  
Q235 Steel ◽  
High Entropy ◽  
Passivation Film ◽  
Elemental Segregation

In this paper, the (CoCrFeNi)95Nb5 high-entropy alloy (HEA) coating with a thickness of 500 μm on Q235 steel substrate was fabricated by plasma spraying. The microscopic results showed that a new Laves phase is formed in the (CoCrFeNi)95Nb5 HEA coating compared to the HEA powder, and elemental segregation occurs between the dendrites and the interdendrites of the coating, while the interdendritic phase enriches with the Cr and Nb. The phase composition change and elemental segregation behavior were mainly due to the faster cooling rate of the plasma spraying technique. At the junction of the coating and the substrate, the HEA coating bonded well to the substrate; in addition, the width of transition zone was merely 2 μm. The microhardness of the (CoCrFeNi)95Nb5 HEA coating was 321 HV0.5, which is significantly higher than that of the substrate. In terms of corrosion resistance, the (CoCrFeNi)95Nb5 HEA coating has good corrosion resistance in NaCl solution. Although the corrosion form was pitting corrosion, the pitting potential of the (CoCrFeNi)95Nb5 HEA coating was significantly higher than that of other coatings, which was mainly because of the dense passivation film formed by Cr and Nb on the surface of the coating. Once the passivation film was destroyed by Cl−, the selective corrosion occurred on the surface of the (CoCrFeNi)95Nb5 HEA coating. In summary, the (CoCrFeNi)95Nb5 HEA coating prepared by plasma spraying technology can significantly improve the corrosion resistance and mechanical properties of the Q235 steel substrate.

AlCoCuFeNi High-Entropy Alloy Coating Fabricated by Laser Cladding with Gas-Atomized Pre-Alloy Powders

2020 ◽  
Vol 993 ◽  
pp. 1148-1154 ◽  
Author(s):  
Mi Na Zhang ◽  
Wen Tai Ouyang ◽  
Jun Ke Jiao ◽  
Wen Wu Zhang ◽  
Xiang Lin Zhou
Keyword(s):  
Temperature Gradient ◽  
Laser Cladding ◽  
Steel Substrate ◽  
Alloy Coating ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Metallurgical Bonding ◽  
High Microhardness ◽  
Fcc Phase ◽  
Equiaxed Grain

AlCoCuFeNi high-entropy alloy coating was prepared by laser cladding with gas-atomized pre-alloy powders. The phase, microstructure and microhardness of HEA coating have been investigated. The results show that the AlCoCuFeNi coating was about ~ 800 μm in thickness, and the hard coating with strong metallurgical bonding to the substrate was obtained. The HEA coating is mainly composed of BCC dendrites phase and Cu-rich FCC phase within the interdendrite. The transition in structure from columnar to equiaxed grain can be observed in the coating due to the effect of different temperature gradient. The laser clad AlCoCuFeNi coating exhibited high microhardness of about 427.7 HV0.2, which was 2.5 times that of the 45# steel substrate.

scholarly journals Synthesis and Characterization of AlCoCrFeNiNbx High-Entropy Alloy Coatings by Laser Cladding

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 56 ◽  
Author(s):  
Hui Jiang ◽  
Kaiming Han ◽  
Dayan Li ◽  
Zhiqiang Cao
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Vickers Hardness ◽  
Testing Machine ◽  
Alloy Coating ◽  
Wear Testing ◽  
304 Stainless Steel ◽  
Molar Ratio ◽  
High Entropy Alloy ◽  
High Entropy

AlCoCrFeNiNbx (x in molar ratio x = 0, 0.25, 0.5, 0.75, and 1.0) high-entropy alloy (HEA) coatings were manufactured on 304 stainless steel by laser cladding. The constituent phases, microstructures, chemical composition, micro-hardness and wear resistance of the HEA coatings were investigated respectively by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), a Vickers hardness tester and a friction/wear testing machine. It was found that an AlCoCrFeNi alloy coating without Nb consisted of body-centered-cubic (BCC) and order BCC (B2) phases, while the AlCoCrFeNiNbx (x > 0) alloy coatings consisted of BCC, B2 and Laves phases. Microstructures of the AlCoCrFeNiNbx alloy coatings evolved from equiaxed grain (x = 0) to hypoeutectic (0.25 ≤ x < 0.75), then to full eutectic (x = 0.75), and finally to hypereutectic (x > 0.75). With increasing Nb content, the Vickers hardness values increased. AlCoCrFeNiNb0.75 alloy coating with a fully eutectic microstructure demonstrated the best wear resistance among the AlCoCrFeNiNbx (x ≥ 0) alloy coatings.

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

Coatings ◽  
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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