Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

Liu, Ning; Chen, Chen; Chang, I.T.H.; Zhou, Pengjie; Wang, Xiao Jing

doi:10.3390/ma11081290

Cited by 25 publications

(9 citation statements)

References 35 publications

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“…The Mo-rich precipitates were identified as the µ phase, having a D8 5 Mo 6 Fe 7 phase crystal structure with the cell parameters a = 4.7196 Å and c = 25.6131 Å. A similar result has been observed in other works from the literature [5,51,52]. Their composition, as shown in Table 2, agrees with the stoichiometry observed, with the participation of other elements from the matrix and with the special importance of Cr, which is not surprising, as this phase appears in the Fe-Cr-Mo system at medium and elevated temperatures [53].…”

Section: As-cast Microstructuresupporting

confidence: 81%

Microstructural Stability of the CoCrFe2Ni2 High Entropy Alloys with Additions of Cu and Mo

Toda‐Caraballo

Jiménez

Milenković

et al. 2021

Metals

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New High Entropy Alloys based on the CoCrFe2Ni2 system have been developed by adding up to 10 at. % of Cu, Mo, and Cu + Mo in different amounts. These alloys showed a single face-centred cubic (FCC) structure after homogenization at 1200 °C. In order to evaluate their thermal stability, aging heat treatments at 500, 700, and 900 °C for 8 h were applied to study the possible precipitation phenomena. In the alloys where only Cu or Mo was added, we found the precipitation of an FCC Cu-rich phase or the µ phase rich in Mo, respectively, in agreement with some of the results previously shown in the literature. Nevertheless, we have observed that when both elements are present, Cu precipitation does not occur, and the formation of the Mo-rich phase is inhibited (or delayed). This is a surprising result as Cu and Mo have a positive enthalpy of mixing, being immiscible in a binary system, while added together they improve the stability of this system and maintain a single FCC crystal structure from medium to high temperatures

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Section: As-cast Microstructuresupporting

confidence: 81%

Microstructural Stability of the CoCrFe2Ni2 High Entropy Alloys with Additions of Cu and Mo

Toda‐Caraballo

Jiménez

Milenković

et al. 2021

Metals

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“…High entropy alloys (HEAs) are composed of five or more elements at equal or nearly equal atomic ratios [1][2][3][4] HEAs tend to form a stable solid solution phase and have excellent mechanical properties and corrosion resistance, unlike the traditional alloys that are typically based on one or two principal elements. Therefore, HEAs have been heavily researched and attracted much attention from the academic community [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Effect of Ti Content on the Microstructure and Corrosion Resistance of CoCrFeNiTix High Entropy Alloys Prepared by Laser Cladding

Wang¹,

Liu²,

Huang³

et al. 2020

Materials

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In this paper, CoCrFeNiTix high entropy alloy (HEA) coatings were prepared on the surface of Q235 steel by laser cladding. The microstructure, microhardness, and corrosion resistance of the coatings were studied. The mechanism of their corrosion resistance was elucidated experimentally and by first-principles calculations. The results show that CoCrFeNiTi0.1 adopts a face-centered cubic (FCC) phase, CoCrFeNiTi0.3 exhibits an FCC phase and a tetragonal FeCr phase, and CoCrFeNiTi0.5 adopts an FCC phase, a tetragonal FeCr phase, and a rhombohedral NiTi phase. The FCC phase, tetragonal FeCr phase, rhombohedral NiTi phase, and hexagonal CoTi phase are all observed in the CoCrFeNiTi0.7 HEA. The alloys assume the dendritic structure that is typical of HEAs. Ni and Ti are enriched in the interdendritic regions, whereas Cr and Fe are enriched in the dendrites. With increasing Ti content, the hardness of the cladding layers also increases due to the combined effects of lattice distortion and dispersion strengthening. When exposed to a 3.5 wt.% NaCl solution, pitting corrosion is the main form of corrosion on the CoCrFeNiTix HEA surfaces. The corrosion current densities of CoCrFeNiTix HEAs are much lower than those of other HEAs. As the Ti content increases, the corrosion resistance is improved. Through X-ray photoelectron spectroscopy (XPS) and first-principles calculations, the origin of the higher corrosion resistance of the coatings is connected to the presence of a dense passivation film. In summary, the corrosion resistance and mechanical properties of CoCrFeNiTi0.5 alloy are much better than the other three groups, which promotes the development of HEA systems with high value for industrial application.

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“…The primary reason for such incorrect prediction with VEC may be the used threshold values of VEC criterion. Even though VEC is the most widely accepted criterion used for predicting the crystal structure of HEAs, [31,41] it suffers from the major limitation of low "correct classification rate" (CCR). [42] Low CCR means that although commonly used thresholds of VEC can predict the crystal structure, they do not offer much improvement to any randomly chosen threshold.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Phase Prediction in Dual‐Phase High‐Entropy Alloys: Computationally Aided Parametric Approach

Negi

Sourav

Heilmaier

et al. 2021

Physica Status Solidi (b)

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Dual‐phase high‐entropy alloys (HEAs) have shown remarkable mechanical properties. However, type and fraction of the secondary phase play a significant role in determining their physical and mechanical properties. CALPHAD is generally used to predict the phases and their fraction in HEAs. Herein, a parameter‐based empirical model is used to predict the phase fraction in dual‐phase HEAs. Valence electron concentration and various measures of atomic size mismatch are utilized for that purpose. A new parameter, namely, critical mismatch factor (δnormalC), is proposed in this work. Experimental verification is done on a series of AlxCoCrFeNi (x = 0.3, 0.5, 0.7) alloys synthesized by vacuum arc melting. Phase fraction is determined by X‐ray diffraction and electron backscatter diffraction analysis. The experimentally determined volume fraction of BCC phase in Al0.3, Al0.5, and Al0.7 is 0%, 6%, and 28–37%, respectively, which agrees closely with the predicted values proving the chosen approach useful.

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Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

Cited by 25 publications

References 35 publications

Microstructural Stability of the CoCrFe2Ni2 High Entropy Alloys with Additions of Cu and Mo

Microstructural Stability of the CoCrFe2Ni2 High Entropy Alloys with Additions of Cu and Mo

Effect of Ti Content on the Microstructure and Corrosion Resistance of CoCrFeNiTix High Entropy Alloys Prepared by Laser Cladding

Quantitative Phase Prediction in Dual‐Phase High‐Entropy Alloys: Computationally Aided Parametric Approach

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