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.

scholarly journals Different-Shaped Ultrafine MoNbTaW HEA Powders Prepared via Mechanical Alloying

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1250 ◽  
Author(s):  
Yonggang Tong ◽  
Peibu Qi ◽  
Xiubing Liang ◽  
Yongxiong Chen ◽  
Yongle Hu ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
High Performance ◽  
Solution Phase ◽  
High Entropy Alloy ◽  
Solid Solution Phase ◽  
Body Centered Cubic ◽  
Homogeneous Microstructure ◽  
High Entropy ◽  
Single Body ◽  
Different Shapes

Different-shaped ultrafine MoNbTaW high-entropy alloy powders were firstly prepared by a convenient mechanical alloying method. The phase composition and microstructure of the powders were characterized. The powders are ultrafine with nano-sized grains and a good homogeneous microstructure. All the powders have a single body-centered cubic solid solution phase and form the high-entropy alloy during mechanical alloying. These powders with different shapes are quite attractive for developing high-performance MoNbTaW high-entropy alloy bulk and coatings combined with a following sintering, spraying, or additive manufacturing technique.

Non-equiatomic W10Mo27Cr21Ti22Al20 high-entropy alloy produced by mechanical alloying and spark plasma sintering: Phase evolution and mechanical properties

2022 ◽  
pp. 146442072110510
Author(s):  
Hamed Naser-Zoshki ◽  
Ali-Reza Kiani-Rashid ◽  
Jalil Vahdati-Khaki
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Elevated Temperatures ◽  
High Entropy Alloy ◽  
Solid Solution Phase ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma

In this work, non-equiatomic W10Mo27Cr21Ti22Al20 refractory high-entropy alloy (RHEA) was produced using mechanical alloying followed by spark plasma sintering. The phase formation, microstructure, and compressive mechanical properties of the alloy were studied. During mechanical alloying, a Body-centered cubic (BCC) solid solution phase with a particle size of less than 1 µm was obtained after 18 h ball milling. The microstructure of the sintered sample exhibits three distinct phases consisting of two solid solution phases BCC1 and BCC2 as well as fine TiCxOy precipitates distributed in them. The volume fractions of each phase were about 79%, 8%, and 13%, respectively. The sintered W10Mo27Cr21Ti22Al20 showed yield strengths of 2465, 1506, 405, and 290 MPa at room temperature 600, 1000, and 1200°C, respectively, which are about twice that of the same refractory high-entropy alloy produced by vacuum arc melting. At 1000 and 1200°C, the strength after yielding gradually increased to 970 and 718 MPa at a compressive strain of 60%. The studied refractory high-entropy alloy can have good potential in high-temperature applications due to its high specific strength at elevated temperatures compared to conventional Ni-based superalloys and most as-reported refractory high-entropy alloys.

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.

Equal-Channel Angular Extrusion of a Low-Density High-Entropy Alloy Produced by High-Energy Cryogenic Mechanical Alloying

JOM ◽  
2014 ◽  
Vol 66 (10) ◽  
pp. 2021-2029 ◽  
Author(s):  
Vincent H. Hammond ◽  
Mark A. Atwater ◽  
Kristopher A. Darling ◽  
Hoang Q. Nguyen ◽  
Laszlo J. Kecskes
Keyword(s):  
Mechanical Alloying ◽  
Equal Channel Angular Extrusion ◽  
High Energy ◽  
High Entropy Alloy ◽  
Low Density ◽  
High Entropy ◽  
Angular Extrusion

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 Fabrication of Nanocrystalline AlCoCrFeNi High Entropy Alloy through Shock Consolidation and Mechanical Alloying

Entropy ◽  
2019 ◽  
Vol 21 (9) ◽  
pp. 880 ◽  
Author(s):  
Ali Arab ◽  
Yansong Guo ◽  
Qiang Zhou ◽  
Pengwan Chen
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Mechanical Alloying ◽  
Electron Backscatter Diffraction ◽  
High Entropy Alloy ◽  
Nano Structure ◽  
High Entropy ◽  
Shock Consolidation ◽  
Before And After ◽  
Backscatter Diffraction

High entropy alloys (HEAs) are usually fabricated using arc melting which has the disadvantages of diseconomy, and the limitations in the shape and size of final products. However, recently, quite a large amount of research has been carried out to find the fabrication techniques for HEAs with better properties such as mechanical alloying and rapid solidification. In this paper, an AlCoCrFeNi high entropy alloy was successfully fabricated by the shock consolidation technique. In this method, the starting powders were mixed by mechanical alloying and then the shock wave was imposed to the compacted powders by explosion. High levels of residual stress existed in samples fabricated by the shock consolidation method. Due to this, after fabrication of the sample, heat treatment was used to eliminate the residual stress and improve the mechanical properties. The microstructure of the samples before and after heat treatment were examined by XRD, SEM and electron backscatter diffraction (EBSD). The shock consolidated sample and sample with heat treatment both showed the nano-structure. After heat treatment the hardness of the sample was decreased from 715 HV to the 624 HV, however the failure strength increased, and as expected the ductility of the sample was improved after heat treatment.

CoCrFeNiMo High Entropy Alloy Produced by Solid State Processing

2017 ◽  
Vol 750 ◽  
pp. 15-19 ◽  
Author(s):  
Ioana Csáki ◽  
Sigrún Nanna Karlsdottir ◽  
Steluța Serghiuță ◽  
Gabriela Popescu ◽  
Mihai Buzatu ◽  
...  
Keyword(s):  
Solid State ◽  
Mechanical Alloying ◽  
Turbine Blades ◽  
High Energy ◽  
Milling Process ◽  
High Entropy Alloy ◽  
Synthesis Methods ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma

Mechanical alloying (MA) is a high-energy ball milling process results in the obtaining of simple and stable microstructures having increased homogeneity compared to other non-equilibrium synthesis methods. The aim of this paper was to develop a high entropy alloy with an improved hardness value suitable for coating turbine blades working in geothermal steam. CoCrFeNiMo high entropy alloy was processed in solid state, using mechanical alloying. After 40h milling time in a planetary ball mill the alloyed sample was consolidated using spark plasma sintering process. The samples obtained were investigated with the aid of optical and electron microscope, X ray diffraction and the hardness value was determined. The results obtained revealed that the powder was completely alloyed after 40 hour milling and the mixture between BCC and FCC phases resulted in 34% improved hardness value in comparison with a stainless steel usually used for turbine blades working in geothermal environment.

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