scholarly journals Influence of Specific Energy on Microstructure and Properties of Laser Cladded FeCoCrNi High Entropy Alloy

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1464
Author(s):  
Leilei Wang ◽  
Zhuanni Gao ◽  
Mengyao Wu ◽  
Fei Weng ◽  
Ting Liu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Specific Energy ◽  
Cubic Phase ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Columnar Crystal ◽  
Positive Role ◽  
High Entropy ◽  
Microstructure And Properties ◽  
Shrinkage Cavities

Specific energy is a key process parameter during laser cladding of high entropy alloy (HEA); however, the effect of specific energy on the microstructure, hardness, and wear resistance of HEA coating has not been completely understood in the literature. This paper aims at revealing the influence of specific energy on the microstructure and properties of laser cladded FeCoCrNi high entropy alloy on the Ti6Al4V substrate, and further obtains feasible process parameters for preparation of HEA coating. Results indicate that there are significant differences in the microstructure and properties of the coatings under different specific energy. The increase of specific energy plays a positive role in coarsening the microstructure, promoting the diffusion of Ti from the substrate to HEA coating, and subsequently affects the hardness of samples. The HEA coating is mainly composed of the face-centered cubic phase and body-centered cubic phase, precipitating a small amount of Fe-Cr phase and Laves phase. Metallurgical bonding is obtained between the base metal and the coatings of which the bonding region is mainly composed of columnar crystal and shrinkage cavities. The microhardness of the HEA coating reaches 1098 HV, which is about 200% higher than that of the TC4 substrate, and the wear resistance is significantly improved by the HEA coating.

scholarly journals Plasma-Nitriding Properties of CoCrFeMnNi High-Entropy Alloys Produced by Spark Plasma Sintering

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 761
Author(s):  
Takato Karimoto ◽  
Akio Nishimoto
Keyword(s):  
Wear Resistance ◽  
Spark Plasma Sintering ◽  
Plasma Nitriding ◽  
Cubic Phase ◽  
High Entropy Alloys ◽  
Face Centered Cubic ◽  
Surface Plasma ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma

High-entropy alloys (HEAs) were fabricated by powder metallurgy using gas-atomized powder and spark plasma sintering (SPS) followed by surface modification (plasma nitriding) of the sintered sample. Plasma nitriding forms nitride and induces solid-soluting of N; it enables the diffusion of N atoms by removing the passive film formed on the surface of alloys such as stainless steel, Al alloys, and Ti alloys, via the sputtering of cations during glow discharge. Therefore, plasma nitriding has the potential to process HEAs that contain strong oxidizing elements such as Cr, Al, and Ti. In this work, a sintered CoCrFeMnNi HEA was plasma-nitrided and its properties were subsequently evaluated. A uniform microstructure without segregation was obtained in the SPS sample, and its hardness and wear resistance were found to have improved. Analysis of the sample surface after nitriding revealed that an expanded face-centered cubic phase formed on the surface plasma-nitrided at 673 K and that a CrN phase formed on the surface plasma-nitrided at temperatures greater than 723 K. The surface hardness of the plasma-nitrided sample was 1200 HV or greater, and the wear resistance and pitting corrosion resistance were improved compared with those of the untreated sample.

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

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 16 ◽  
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.

scholarly journals Effects of Annealing on the Microstructure and Wear Resistance of Laser Cladding CrFeMoNbTiW High-Entropy Alloy Coating

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1096
Author(s):  
Qiang Shen ◽  
Yan Li ◽  
Jing Zhao ◽  
Dezheng Liu ◽  
Yongsheng Yang
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
Alloy Coating ◽  
Resistance Testing ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hardness Tester

In this study, a CrFeMoNbTiW high-entropy alloy (HEA) coating was prepared on a Q245R steel (American grade: SA515 Gr60) substrate by means of laser cladding. The effects of annealing temperature on the microstructure and wear resistance of the CrFeMoNbTiW coating were investigated using X-ray diffraction (XRD), a scanning electron microscope (SEM), a Vickers hardness tester and a roller friction wear tester. The results showed that the coating was mainly composed of body-centered cubic (BCC) solid solution and face-centered cubic (FCC) structural (Nb,Ti)C carbides prior to annealing, exhibiting an interdendritic structure and needlelike dendritic crystal structure with average microhardness of 682 HV0.2. The coarsening of the dendrite arms increased gradually after a 10-h long annealing treatment at 800 °C, 900 °C and 1000 °C, and a small amount of Laves phase was produced. After annealing, the highest microhardness value of the as-annealed coating reached 1176 HV0.2, which represents an increase of approximately 72.5% compared to that of the as-deposit coating. The wear resistance testing results imply that this type of coating retains good wear resistance following the annealing treatment and that its wear resistance increases in proportion to the annealing temperature in a range from 800 °C to 1000 °C.

Microstructure Refinement in the CoCrFeNiMn High Entropy Alloy under Plastic Straining

2016 ◽  
Vol 879 ◽  
pp. 1853-1858 ◽  
Author(s):  
Nikita Stepanov ◽  
Dmitry Shaysultanov ◽  
Nikita Yurchenko ◽  
Margarita Klimova ◽  
Sergey Zherebtsov ◽  
...  
Keyword(s):  
Yield Strength ◽  
Volume Fraction ◽  
Dominant Role ◽  
Mechanical Twinning ◽  
Cubic Phase ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Cryogenic Temperatures ◽  
High Entropy ◽  
Average Grain Size

The effect of plastic deformation under various conditions of the equiatomic CoCrFeNiMn alloy with single face-centered cubic phase structure was studied. The alloy was rolled at room and cryogenic temperatures, and uniaxially compressed at room temperature and temperatures of 600-1100°C with different height reductions. In addition, multiaxial forging at 900-1000°C was performed. Scanning and transmission electron microscopy, including EBSD analysis, was widely employed to characterize microstructure of the deformed alloy. At room and cryogenic temperatures, mechanical twinning and shear banding plays play dominant role in microstructure evolution. Extensive refinement of the microstructure occurs as the result of rolling with reduction of 80%. During deformation at 600-1100°C, discontinuous dynamic recrystallization takes place. The recrystallized grains size and their volume fraction increases with increase of deformation temperature. Multiaxial forging at 900-1000°C was used to produce fully recrystallized structure with average grain size of 6.7 μm. The alloy in the initial condition had low yield strength of 160 Mpa but remarkable tensile ductility of 68%. Rolling substantial increases yield strength to 1120-1290 MPa, but results in loss of ductility. After multiaxial forging the alloy has balanced combination of properties – yield strength of 280 MPa and elongation of 56%.

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.

scholarly journals Effects of Boron Content on Microstructure and Wear Properties of FeCoCrNiBx High-Entropy Alloy Coating by Laser Cladding

2019 ◽  
Vol 10 (1) ◽  
pp. 49 ◽  
Author(s):  
Dezheng Liu ◽  
Jing Zhao ◽  
Yan Li ◽  
Wenli Zhu ◽  
Liangxu Lin
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Alloy Coating ◽  
Rolling Friction ◽  
Substrate Material ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Micro Hardness ◽  
Wear Properties ◽  
High Entropy

The FeCoCrNiBx high-entropy alloy (HEA) coatings with three different boron (B) contents were synthesized on Q245R steel (American grade: SA515 Gr60) by laser cladding deposition technology. Effects of B content on the microstructure and wear properties of FeCoCrNiBx HEA coating were investigated. In this study, the phase composition, microstructure, micro-hardness, and wear resistance (rolling friction) were investigated by X-ray diffraction (XRD), a scanning electron microscope (SEM), a micro hardness tester, and a roller friction wear tester, respectively. The FeCoCrNiBx coatings exhibited a typical dendritic and interdendritic structure, and the microstructure was refined with the increase of B content. Additionally, the coatings were found to be a simple face-centered cubic (FCC) solid solution with borides. In terms of mechanical properties, the hardness and wear resistance ability of the coating can be enhanced with the increase of the B content, and the maximum hardness value of three HEA coatings reached around 1025 HV0.2, which is higher than the hardness of the substrate material. It is suggested that the present fabricated HEA coatings possess potentials in application of wear resistance structures for Q245R steel.

scholarly journals Anisotropic Response of CoCrFeMnNi High-Entropy Alloy Fabricated by Selective Laser Melting

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5687
Author(s):  
Bowen Wang ◽  
Miao Sun ◽  
Bobo Li ◽  
Lijuan Zhang ◽  
Bingheng Lu
Keyword(s):  
Crystal Structure ◽  
Selective Laser Melting ◽  
Fiber Texture ◽  
Solidification Structure ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
Laser Melting ◽  
Corrosion Properties ◽  
Columnar Crystal ◽  
High Entropy

This study investigated the anisotropic characteristics of the microstructural, mechanical and corrosion properties of CoCrFeMnNi high-entropy alloy produced by selective laser melting (SLM) additive manufacturing (AM). Under the extremely high thermal gradient during the SLM process, a columnar solidification structure with a single face-centered cubic (FCC) phase structure was formed. The crystal structure exhibited a regular checkerboard structure in the XOY plane (perpendicular to the building direction), which was composed of {110} direction and a small amount of {100} fiber texture. The cellular-dendritic sub-structures formed in the columnar crystal structure with sizes of about 500 nm in diameter. As for the mechanical properties, the XOY plane exhibited higher ultimate tensile strength and yield strength (σ0.2) but lower elongation to failure compared to the XOZ plane (parallel to building direction), which reflected the anisotropy of the microstructure. The electrochemical test results of the different planes showed that the XOZ plane exhibited better corrosion resistance in comparison with the XOY plane in the 3.5 wt % NaCl solution, which was on account of the selective attack at the Mn-rich inter-cellular regions and the different structures of the cellular-dendritic sub-structures on different planes.

Effect of Titanium Content on Microstructure and Properties of FeWCrMnCoCuTix High Entropy Alloy Coating Prepared by Laser Cladding

2014 ◽  
Vol 563 ◽  
pp. 25-29
Author(s):  
Xu Long An ◽  
Qi Bin Liu ◽  
Bo Zheng
Keyword(s):  
Laser Cladding ◽  
Alloy Coating ◽  
Titanium Content ◽  
Experimental Result ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Microstructure And Properties ◽  
Simple Body ◽  
Ti Content

To obtain the coating with excellent properties, FeWCrMnCoCuTix(x=0.2, 0.4, 0.6) high entropy alloys coating on 45 steel were prepared by laser cladding. By means of OM, XRD and microhardness tester, the effect of Ti content on microstructure and properties of coating is investigated. The experimental result shows that the phase composition of HEAs coating is simple body-centered cubic and face-centered cubic. The microstructure of these alloys is mainly dendrite crystal with grains were fine and uniform. When Ti content increases tox=0.4, the hardness of the coating reaches a maximum (639HV0.2). Key words: HEAs; FeWCrMnCoCuTix; coating; laser cladding; microstructure and properties

Microstructure and Properties of a Co-Free Fe50mn27ni10cr13 High Entropy Alloy

2020 ◽  
Author(s):  
Raymond Kwesi Nutor ◽  
Muhammad Azeemullah ◽  
Q. P. Cao ◽  
X. D. Wang ◽  
D.X. Zhang ◽  
...  
Keyword(s):  
High Entropy Alloy ◽  
High Entropy ◽  
Microstructure And Properties
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