Effect of annealing heat treatment on microstructure and mechanical properties of nonequiatomic CoCrFeNiMo medium-entropy alloys prepared by hot isostatic pressing

Zhang, Yali; Jiang, Xiaosong; Sun, Huilan; Shao, Zhang

doi:10.1515/ntrev-2020-0047

Cited by 17 publications

(3 citation statements)

References 60 publications

(77 reference statements)

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“…The phase composition was represented by 67 vol.% of ε-phase (Co 0.62 Cr 0.38 ) and 33 vol.% of σ-phase (Co 0.4 Cr 0.6 ). A 14-hours annealing led to the total decay of the intermetallic µ-phase [40].…”

Section: Resultsmentioning

confidence: 99%

Influence of thermal treatment duration on structure and phase composition of additive Co-Cr-Mo alloy samples

et al. 2022

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Laser powder bed fusion (LPBF) requires application of powders with specific characteristics. These are near-spherical shape of particles, uniform elemental composition, typical particle size of 5 -70 µm, etc. Such powders are produced by spheroidization methods. They have such disadvantages as high cost and sale only in large quantities. There are publications describing application in LPBF powders, produced by the methods, alternative to spheroidization. In the current study, powders of pure raw Co, Cr and Mo were used for the production of Co-Cr-Mo powder mixture. Samples of Co-28 wt.% Cr-6 wt.% Mo alloy were produced by LPBF from this powder mixture. Due to the difference between melting temperatures of Co, Cr and Mo, inclusions of Cr and Mo were formed within the bulk of samples. Studies of phase and elemental composition, structure and microhardness of the as-produced samples and after post-treatment with varied duration are represented. As-produced samples have non-uniform elemental composition and are represented by the main Co-based phase. Increasing the annealing duration leads to the sequential dissolution of un-melted Cr and Mo inclusions. Complete dissolution of Cr particles was observed at 10 hours of treatment and complete dissolution of Mo particles was not observed after 20 hours of annealing. Microhardness non-linearly changes with the increasing duration of annealing. This is due to the phase transformations and diffusion processes occurring at such type of post-treatment. Complete dissolution of Mo-particles could be achieved by further increasing the annealing time or by varying the mode of laser powder bed fusion.

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Section: Resultsmentioning

confidence: 99%

Influence of thermal treatment duration on structure and phase composition of additive Co-Cr-Mo alloy samples

et al. 2022

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“…The effects of temperature on the properties of HEAs were studied through processes such as: annealing and heat treatments [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104] and thermomechanical processing [105][106][107][108]. A number of research groups reported how temperature affected the microstructures and mechanical properties of HEAs in various manufacturing processes [96,[109][110][111][112]. Moreover, the physical or chemical responses of various HEAs under a variety of thermal histories during manufacturing were studied: thermal aging behavior [86,[113][114][115], TaNbHfZrTi synthesis by hydrogenation-dehydrogenation reaction and thermal plasma treatment [116], martensite formation [117][118][119][120], Al x CoCrFeNi formation with high gravity combustion from oxides [121], laser surface melting [122], precipitation behavior [123][124][125]…”

Section: Background and Conventional Methodsmentioning

confidence: 99%

Recent Advances in Additive Manufacturing of High Entropy Alloys and Their Nuclear and Wear-Resistant Applications

Sonal

Lee

2021

Metals

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Alloying has been very common practice in materials engineering to fabricate metals of desirable properties for specific applications. Traditionally, a small amount of the desired material is added to the principal metal. However, a new alloying technique emerged in 2004 with the concept of adding several principal elements in or near equi-atomic concentrations. These are popularly known as high entropy alloys (HEAs) which can have a wide composition range. A vast area of this composition range is still unexplored. The HEAs research community is still trying to identify and characterize the behaviors of these alloys under different scenarios to develop high-performance materials with desired properties and make the next class of advanced materials. Over the years, understanding of the thermodynamics theories, phase stability and manufacturing methods of HEAs has improved. Moreover, HEAs have also shown retention of strength and relevant properties under extreme tribological conditions and radiation. Recent progresses in these fields are surveyed and discussed in this review with a focus on HEAs for use under extreme environments (i.e., wear and irradiation) and their fabrication using additive manufacturing.

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“…Among them, CoCrFeNiMo high-entropy alloys have high resistance to fatigue crack extension [5], while the presence of an FCC matrix and hard intermetallic compounds formed by Mo with Fe, Co, and Ni gives them good overall mechanical properties [6][7][8]. Zhang et al [9] adopted an annealing treatment to a CoCrFeNiMo highentropy alloy prepared through hot isostatic pressing, which can lead to a large amount of µ phase inside and can further improve its compressive strength and inhibit cracking. Wu et al [10] formed a CoCrFeNiMo high-entropy alloy with a denser structure through magnetic levitation melting technology, and, due to the presence of Ni, Cr, and Mo elements, it has excellent high-temperature wear resistance.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Microstructure and Properties of CoCrFeNiMo High-Entropy Alloy Coating Prepared through High-Speed Laser Cladding

Zhang

Wang

et al. 2023

Coatings

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High-speed laser cladding was introduced to prepare a CoCrFeNiMo high-entropy alloy (HEA) coating. The microstructure, composition distribution, micromechanical properties, and corrosion resistance of the CoCrFeNiMo coating were characterized. As a result, the coating exhibited a dual FCC- and BCC-phase structure, and the grain size of the coating prepared through high-speed laser cladding was only 2~5 μm. The upper and lower parts of the coating were composed of equiaxed cellular crystals and slender columnar crystals, respectively. The interdendritic structure was a Mo-rich phase that was distributed in a network-like pattern. The nanoindentation tests revealed that the interdendritic BCC phase had high hardness and an elastic modulus as well as excellent resistance to deformation, while the intradendritic FCC phase possessed superior crack propagation resistance. In addition, the two phases could generate cooperative elastic deformation during the elastic deformation stage. The electrochemical performance of the coating was tested in 3.5 wt% NaCl solution, and the corrosion potential Ecorr and corrosion current density Icorr of the coating were −0.362 V and 3.69 × 10−6 A/cm2, respectively. The high-speed laser cladding CoCrFeNiMo HEA coating had excellent corrosion resistance thanks to the presence of the easily passivating element Mo and grain refinement.

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Effect of annealing heat treatment on microstructure and mechanical properties of nonequiatomic CoCrFeNiMo medium-entropy alloys prepared by hot isostatic pressing

Cited by 17 publications

References 60 publications

Influence of thermal treatment duration on structure and phase composition of additive Co-Cr-Mo alloy samples

Influence of thermal treatment duration on structure and phase composition of additive Co-Cr-Mo alloy samples

Recent Advances in Additive Manufacturing of High Entropy Alloys and Their Nuclear and Wear-Resistant Applications

Investigation of the Microstructure and Properties of CoCrFeNiMo High-Entropy Alloy Coating Prepared through High-Speed Laser Cladding

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