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.

Grain growth kinetics in CoCrFeNi and CoCrFeMnNi high entropy alloys processed by spark plasma sintering

2019 ◽  
Vol 791 ◽  
pp. 1114-1121 ◽  
Author(s):  
M. Vaidya ◽  
Ameey Anupam ◽  
J. Vijay Bharadwaj ◽  
Chandan Srivastava ◽  
B.S. Murty
Keyword(s):  
Grain Growth ◽  
Spark Plasma Sintering ◽  
Growth Kinetics ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Grain Growth Kinetics

scholarly journals Designing (Ultra)Fine-Grained High-Entropy Alloys by Spark Plasma Sintering and Equal-Channel Angular Pressing

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1157
Author(s):  
Lisa-Marie Rymer ◽  
Thomas Lindner ◽  
Philipp Frint ◽  
Martin Löbel ◽  
Thomas Lampke
Keyword(s):  
Tensile Strength ◽  
Grain Refinement ◽  
Spark Plasma Sintering ◽  
Equal Channel Angular Pressing ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Fine Grained ◽  
Angular Pressing ◽  
Plasma Sintering ◽  
Spark Plasma

Single-phase, face-centered cubic (FCC) high-entropy alloys (HEA) are promising materials for future applications. In order to improve the mechanical properties, especially the tensile strength of these materials, this study focuses on the combination of spark plasma sintering (SPS) and equal-channel angular pressing (ECAP). The initial fine-grained microstructure produced by SPS is further refined by ECAP in a 90°-die. Optical microscopy and electron backscatter diffraction (EBSD) confirm this considerable grain refinement, leads to a grain size below 1 µm after 1 ECAP pass. An alternating arrangement of fine-grained areas and much coarser regions, aligned under an angle of approximately 27°, is found. Moreover, a first microstructural investigation of the twin structure is conducted. The mechanical behavior was investigated by hardness measurements and tensile testing. Both the hardness and tensile strength are remarkably increased after ECAP. In contrast, the uniform elongation and elongation at fracture are significantly reduced due to the strengthening mechanisms of strain hardening and grain refinement. It is concluded that the combination of SPS and ECAP is an attractive approach for designing (ultra)fine-grained HEAs with superior properties. The investigated techniques could be applied to understand the underlying microstructural mechanisms.

Synthesis of CuCrFeNiTiAlx high entropy alloys by means of mechanical alloying and spark plasma sintering

2021 ◽  
pp. 1-9
Author(s):  
Gabriela E. Ruiz-Jasso ◽  
Sebastián Díaz-de la Torre ◽  
Ricardo Escalona-González ◽  
J. Claudio Méndez-García ◽  
José A. Castillo Robles ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Plasma Sintering ◽  
Spark Plasma

Characterization of Powder Metallurgy High-Entropy Alloys Prepared by Spark Plasma Sintering

2018 ◽  
Vol 941 ◽  
pp. 1053-1058 ◽  
Author(s):  
Larissa Gouvea ◽  
Igor Moravcik ◽  
Jan Cizek ◽  
Petra Krajnakova ◽  
Vít Jan ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
High Entropy ◽  
Average Hardness ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Multi Phase ◽  
Sintering Processes

In the present work, the High-Entropy Alloys Al0.2Co1.5CrFeNi1.5Ti, Al1.3Co1.4Cr2.0FeNi4.0Ti4.0 and Al6.0Co1.2Cr2.5FeNi3.5Ti6.0 were produced by Mechanical Alloying and subsequent Spark Plasma Sintering processes to obtain properly densified bulks. The characterization of the materials was accomplished through X-Ray Diffraction, Scanning Electron Microscopy, microhardness and nanoindentation tests to identify and analyze the acquired microstructures’ features, phases formed, morphology and size of the grains and its average hardness. The results indicate that it was possible to obtain alloys presenting high values of hardness and multi-phase microstructures. The effect of the multiple phases on the microstructures was discussed in terms of its influence on the mechanical properties. A satisfying densification level of the materials was achieved with the selected parameters.

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