Microstructure and properties of CoCrFeNiMo0.2 high-entropy alloy enhanced by high-current pulsed electron beam

Lyu, Peng; Peng, Tao; Miao, Yingqi; Liu, Zijian; Gao, Qi; Zhang, Conglin; Jin, Yunxue; Guan, Qingfeng; Cai, Jie

doi:10.1016/j.surfcoat.2021.126911

Cited by 46 publications

(13 citation statements)

References 42 publications

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“…In the results of the EDS analyses, we can also observe the oxygen component of the occurred passivation layer. Probably, Lyu et al [38] determined the corrosion potential Ecorr (mV) for an alloy with 0.2 Mo, CoCrFeNiMo 0.2 . The value determined by them, in the same corrosion conditions 3.5%NaCl at room temperature is much more negative, −907 mV, indicating a higher susceptibility to corrosion.…”

Section: Discussionmentioning

confidence: 99%

Mechanically Alloyed CoCrFeNiMo0.85 High-Entropy Alloy for Corrosion Resistance Coatings

et al. 2021

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High-entropy alloys could provide a solution for corrosion resistance due to their impressive properties. Solid-state processing of high purity Co, Cr, Fe, Ni and Mo metallic powders and consolidation resulted in a bulk material that was further machined into electro spark deposition electrodes. After the stainless steel substrate surface preparation, thin successive layers of the high-entropy alloy were deposited and Pull-Off testing was performed on the newly obtained coating, for a better understanding of the adhesion efficiency of this technique. Good adhesion of the coating to the substrate was proved by the test and no cracks or exfoliations were present. Corrosion resistance testing was performed in a liquid solution of 3.5 wt.% NaCl for 6 hours at room temperature and the results obtained validated our hypothesis that CoCrFeNiMo0.85 high-entropy alloys could provide corrosion resistance when coating a stainless steel substrate.

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Section: Discussionmentioning

confidence: 99%

Mechanically Alloyed CoCrFeNiMo0.85 High-Entropy Alloy for Corrosion Resistance Coatings

et al. 2021

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“…Recent publications demonstrate successful PBF-LB/M of this group of alloys [ 9 , 10 ], investigate the effect of C [ 11 ] and N [ 12 ] additions, or examine the wear resistance [ 13 ]. Besides PBF-LB/M, different additive manufacturing processes such as wire arc additive manufacturing [ 14 ], electron beam melting [ 15 , 16 ] or laser liquid phase sintering [ 17 ] of 3d transition metal high entropy alloys are subjects of ongoing research. In contrast to that, refractory metal high entropy alloys are by far less investigated [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

In-Situ Alloy Formation of a WMoTaNbV Refractory Metal High Entropy Alloy by Laser Powder Bed Fusion (PBF-LB/M)

2021

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High entropy or multi principal element alloys are a promising and relatively young concept for designing alloys. The idea of creating alloys without a single main alloying element opens up a wide space for possible new alloy compositions. High entropy alloys based on refractory metals such as W, Mo, Ta or Nb are of interest for future high temperature applications e.g., in the aerospace or chemical industry. However, producing refractory metal high entropy alloys by conventional metallurgical methods remains challenging. For this reason, the feasibility of laser-based additive manufacturing of the refractory metal high entropy alloy W20Mo20Ta20Nb20V20 by laser powder bed fusion (PBF-LB/M) is investigated in the present work. In-situ alloy formation from mixtures of easily available elemental powders is employed to avoid an expensive atomization of pre-alloyed powder. It is shown that PBF-LB/M of W20Mo20Ta20Nb20V20 is in general possible and that a complete fusion of the powder mixture without a significant number of undissolved particles is achievable by in-situ alloy formation during PBF-LB/M when selecting favorable process parameter combinations. The relative density of the samples with a dimension of 6 × 6 × 6 mm3 reaches, in dependence of the PBF-LB/M parameter set, 99.8%. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) measurements confirm the presence of a single bcc-phase. Scanning electron microscopy (SEM) images show a dendritic and/or cellular microstructure that can, to some extent, be controlled by the PBF-LB/M parameters.

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“…In recent years, the effect of concentrated energy flows, e. g. low energy high current electron beams on high-entropy alloys with different chemical formulae, has been the subject of many research works [1][2][3][4][5]. These works have demonstrated that multiple irradiations of CrFeCoNiMo and CoCrFeNiMo 0.2 alloys by an electron beam with an energy density of 4 J / cm 2 and a pulse time of 1.5 μs induces the formation of a fusion zone.…”

Section: Introductionmentioning

confidence: 99%

“…These works have demonstrated that multiple irradiations of CrFeCoNiMo and CoCrFeNiMo 0.2 alloys by an electron beam with an energy density of 4 J / cm 2 and a pulse time of 1.5 μs induces the formation of a fusion zone. Moreover, its thickness expands with the increasing number of pulses [1,2]. The structure of this zone comprises crystals with an average size of 109 nm.…”

Section: Introductionmentioning

confidence: 99%

“…An assumption was made [11,12] that micro-and nanostructure phase states develop in multicomponent alloys owing to the evolving combination of thermal, concentration-evaporation and thermoelectric instabilities. This study investigates the effect of an electron beam with the energy density from 10 to 30 J / cm 2 from 225.83 to 618.87 nm was formed on the treated surface. The dimensional distribution of cells displays one maximum in the range from 300 to 350 nm.…”

Section: Introductionmentioning

confidence: 99%

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The mechanism of formation of surface micro- and nanostructures in the AlCoCrFeNi high-entropy alloy during electron-beam treatment

et al. 2021

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The paper is devoted to a study of the formation of submicron and nanosized cellular crystallization structures on the surface of a high-entropy AlCoCrFeNi alloy irradiated by high current electron beams with the energy density varying from 10 to 30 J / cm 2 and a pulse time of 200 μs. The study revealed that the combination of thermal, evaporation-capillary and thermoelectric instabilities induces the formation of submicro-and nanodimensional cellular structures similarly to high-entropy alloys. The proposed dispersion equation was analyzed to detect the conditions for the generation of this instability. The importance of the evaporation process was investigated by finding a solution to the heat problem with phase transformations. The temperature distribution over time calculated at different distances from the surface of the alloy samples demonstrated that the surface temperature is lower than the evaporation temperature for the energy density E s < 30 J / cm 2 , therefore, the term of evaporation in the dispersion equation was ignored for these values of the energy density. The analysis of the dispersion equation showed that for E s = 30 J / cm 2 , the wavelength λ m with the maximal growth rate of perturbations on the melt surface gains a value in the submicro-and nano-range, provided that the thermoelectric coefficient equals to ~4 -10 V / K, and the pressure of evaporation is ~10 5 Pa. If we exclude thermoelectric effects, these values λ m are observed for the pressure of evaporation ~10 11 Pa. The wavelength λ m was revealed to decrease according to a power law as the beam energy density increases.

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Microstructure and properties of CoCrFeNiMo0.2 high-entropy alloy enhanced by high-current pulsed electron beam

Cited by 46 publications

References 42 publications

Mechanically Alloyed CoCrFeNiMo0.85 High-Entropy Alloy for Corrosion Resistance Coatings

Mechanically Alloyed CoCrFeNiMo0.85 High-Entropy Alloy for Corrosion Resistance Coatings

In-Situ Alloy Formation of a WMoTaNbV Refractory Metal High Entropy Alloy by Laser Powder Bed Fusion (PBF-LB/M)

The mechanism of formation of surface micro- and nanostructures in the AlCoCrFeNi high-entropy alloy during electron-beam treatment

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