Effect of sintering temperature on microstructural and mechanical properties of SPS processed CoCrCuFeNi based ODS high entropy alloy

A nanostructured oxide‐dispersion‐strengthened (ODS) CoCrFeMnNi high‐entropy alloy (HEA) is synthesized by a powder metallurgy process. The thermal stability, including the grain size and crystal structure of the HEA matrix and oxide dispersions, is carefully investigated by X‐ray diffraction (XRD) and electron microscopy characterizations after annealing at 900 °C. The limited grain growth may be attributed to Zener pinning of yttria dispersions that impede the grain boundary mobility and diffusivity. The high hardness is caused by both the fine grain size and yttria dispersions, which are also retained after annealing at 900 °C. Herein, it is implied that the combination of ODS and HEA concepts may provide a new design strategy for the development of thermally stable nanostructured alloys for extreme environments.

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“…λ and d particle represent the interparticle spacing and diameter of oxide particles, respectively.

α (d_{particle})

is the obstacle strength coefficient, which is given by [ 58 ]

α (d_{particle}) = - 0.017 + 0.374 log (\frac{d_{particle}}{4 b})

…”

Section: Resultsmentioning

confidence: 99%

Nanostructured Oxide‐Dispersion‐Strengthened CoCrFeMnNi High‐Entropy Alloys with High Thermal Stability

et al. 2021

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“…The presence of carbides and oxides, however, has been proven to contribute to the strength, high-temperature stability, and wear resistance of metallic materials [ 26 , 27 , 49 ], including HEAs [ 20 , 21 , 29 , 50 , 51 , 52 ], similar to the strengthening effect used in advanced oxide dispersion strengthened (ODS) superalloys [ 25 ]. Often, the strengthening effect due to the formation of oxides and carbides is followed by a decrease in ductility [ 53 ].…”

Section: Discussionmentioning

confidence: 99%

Tailoring a Refractory High Entropy Alloy by Powder Metallurgy Process Optimization

et al. 2021

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This paper reports the microstructural evolution and mechanical properties of a low-density Al0.3NbTa0.8Ti1.5V0.2Zr refractory high-entropy alloy (RHEA) prepared by means of a combination of mechanical alloying and spark plasma sintering (SPS). Prior to sintering, the morphology, chemical homogeneity and crystal structures of the powders were thoroughly investigated by varying the milling times to find optimal conditions for densification. The sintered bulk RHEAs were produced with diverse feedstock powder conditions. The microstructural development of the materials was analyzed in terms of phase composition and constitution, chemical homogeneity, and crystallographic properties. Hardness and elastic constants also were measured. The calculation of phase diagrams (CALPHAD) was performed to predict the phase changes in the alloy, and the results were compared with the experiments. Milling time seems to play a significant role in the contamination level of the sintered materials. Even though a protective atmosphere was used in the entire manufacturing process, carbide formation was detected in the sintered bulks as early as after 3 h of powder milling. Oxides were observed after 30 h due to wear of the high-carbon steel milling media and SPS consolidation. Ten hours of milling seems sufficient for achieving an optimal equilibrium between microstructural homogeneity and refinement, high hardness and minimal contamination.

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“…A detailed description of the manufacturing technology and the relationship between the microstructure and mechanical properties of CoCrCu x FeNi HEAs was provided in refs [ 38 , 39 , 40 , 41 , 42 , 43 ]. Unlike other HEAs belonging to the CoCrFeNi family, the mechanical properties of copper-containing alloys are studied only upon compression, thus precluding one from drawing an unambiguous conclusion about whether copper is beneficial.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing of Metal–Diamond Composites with High-Strength CoCrCuxFeNi High-Entropy Alloy Used as a Binder

et al. 2023

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This paper focuses on the study of the structure and mechanical properties of CoCrCuxFeNi high-entropy alloys and their adhesion to single diamond crystals. CoCrCuxFeNi alloys were manufactured by the powder metallurgy route, specifically via mechanical alloying of elemental powders, followed by hot pressing. The addition of copper led to the formation of a dual-phase FCC + FCC2 structure. The CoCrCu0.5FeNi alloy exhibited the highest ultimate tensile strength (1080 MPa). Reductions in the ductility of the CoCrCuxFeNi HEAs and the tendency for brittle fracture behavior were observed at high copper concentrations. The equiatomic alloys CoCrFeNi and CoCrCuFeNi demonstrated high adhesion strength to single diamond crystals. The diamond surface at the fracture of the composites having the CoCrFeNi matrix had chromium-rich metal matrix regions, thus indicating that chromium carbide, responsible for adhesion, was formed at the composite–diamond interface. Copper-rich areas were detected on the diamond surface within the composites having the CoCrCuFeNi matrix due to the predominant precipitation of the FCC2 phase at the interfaces or the crack propagation along the FCC/FCC2 interface, resulting in the exposure of the Cu-rich FCC2 phase on the surface.

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Effect of sintering temperature on microstructural and mechanical properties of SPS processed CoCrCuFeNi based ODS high entropy alloy

Cited by 24 publications

References 31 publications

Nanostructured Oxide‐Dispersion‐Strengthened CoCrFeMnNi High‐Entropy Alloys with High Thermal Stability

Nanostructured Oxide‐Dispersion‐Strengthened CoCrFeMnNi High‐Entropy Alloys with High Thermal Stability

Tailoring a Refractory High Entropy Alloy by Powder Metallurgy Process Optimization

Manufacturing of Metal–Diamond Composites with High-Strength CoCrCuxFeNi High-Entropy Alloy Used as a Binder

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