Designing High Entropy Alloys with Dual fcc and bcc Solid-Solution Phases: Structures and Mechanical Properties

Tang, Zihui; Zhang, Shang; Cai, Ruipeng; Zhou, Qing; Wang, Haifeng

doi:10.1007/s11661-019-05131-1

Cited by 43 publications

(17 citation statements)

References 61 publications

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“…In this work, the CCA composition was selected based on its likelihood to provide significant performance in terms of both tribological and corrosion resistance. For tribological performance (e.g., resistance to erosion), a mixture of FCC and BCC structures would be expected to provide adequate performance as the FCC phase is expected to present a ductile nature while the opposite holds for a BCC crystal structure [14]. Resistance to corrosion is instead expected to be enhanced by elements such as Ni, Mo, and Cr, due to the formation of passive films on the alloys surface [15].…”

Section: Cca Composition Designmentioning

confidence: 99%

Effect of Microstructural Modifications on the Corrosion Resistance of CoCrFeMo0.85Ni Compositionally Complex Alloy Coatings

Fanicchia¹,

Csáki

Geambazu

et al. 2019

Coatings

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A compositionally complex alloy (CCA) was developed in powder form and applied as a coating onto a carbon steels substrate by using thermal spray. The purpose of this study was to investigate the effect of microstructural modification induced by using two different powder production methods, mechanical alloying and gas atomisation, onto the corrosion resistance of the coatings for a CoCrFeMo 0.85 Ni composition. The evolution of microstructure from powders to coatings was analysed using scanning electron microscopy coupled with energy-dispersive spectroscopy and X-ray diffraction. In order to evaluate the corrosion performance of the coatings, electrochemical corrosion tests were performed in a 3.5 wt % NaCl solution at pH = 4. The study demonstrates that the powder production method has a significant influence on the phase composition and, in turn, corrosion behaviour of the resulting coating, with the gas atomising route imparting better corrosion resistance properties. Nevertheless, the appearance of the face-centered cubic (FCC) phase characteristic of the CoCrFeMo 0.85 Ni alloy within the coating produced from the mechanically alloyed powder, opens the possibility for this powder manufacturing technique to effectively produce compositionally complex alloys.Coatings 2019, 9, 695 2 of 16 and consisted of Laves phase within an FCC solid solution. Elemental segregation was observed, with higher melting point elements (Cu, Nb) enriching the interdendritic regions. Better corrosion performance than previously studied coatings was measured in 3.5 wt % NaCl solution, with the Cu and Nb-rich regions representing the areas of preferential corrosion. In another work by Gao et al. [6], CCA of the CoCrFeNiAl 0.3 composition was produced by using radio frequency magnetron sputtering and tested in 3.5 wt % NaCl solution. The coatings consisted of a polycrystalline FCC structure with homogeneous element distribution and showed increased hardness and improved corrosion performance as compared to wrought 304 stainless steel. Some CCAs have demonstrated excellent performance in both H 2 SO 4 and NaCl solutions. Similar to conventional alloys, it is interesting to note that Cr, Ni, Co, Ti in CCAs enhance corrosion resistance in acid solutions, Mo tends to inhibit pitting corrosion, whereas Al and Mn display a negative effect [7]. Wang et al. [8] applied thermal spray technology to fabricate coatings of the Ni x Co 0.6 Fe 0.2 Cr y Si z AlTi 0.2 composition. Results indicated that the hardness of the CCAs prepared by using the thermal spraying in combination with annealing at 1100 • C for 10 h was significantly increased compared to that of the cast alloy. Moreover, the alloy exhibited excellent corrosion resistance, resulting from the presence of the Cr 3 Si phase and several other (unidentified) phases. More recently, the effect of grain refinement and elemental partitioning onto the strength and corrosion resistance of a friction stir processed Cu-containing CCA has been evaluated by Nene et al. [9]. Their work shows that grai...

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Section: Cca Composition Designmentioning

confidence: 99%

Effect of Microstructural Modifications on the Corrosion Resistance of CoCrFeMo0.85Ni Compositionally Complex Alloy Coatings

Fanicchia¹,

Csáki

Geambazu

et al. 2019

Coatings

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“…To date, the most commonly used criterion for phase prediction in HEAs is VEC. [ 31,32 ] VEC for a multicomponent alloy can be defined as the weighted average of VEC of the constituent components [ 33 ]

VEC = \sum_{i = 1}^{n} C_{i} {false(VEC false)}_{i}

with

{false(VEC false)}_{i}

being the VEC for the i th element. Presumably, the most widely accepted criterion for crystal structure prediction was given by Guo et al, who proposed that FCC is stable for VEC ≥ 8 and BCC is stable at VEC < 6.87.…”

Section: Resultsmentioning

confidence: 99%

“…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%

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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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“…Composition-specific features can further be developed from the Alloy specification Columns 3 to 27 correspond to the elemental compositions of the multi-component alloy while Column 28 corresponds to the number of elements making up the multi-component alloy system ( Num_of_Elem ). Columns 29 to 37 correspond to some typical empirical HEA design parameters [ 6 , 7 ] such as the density estimate ( Density_calc ), the enthalpy of mixing for a multi-component alloy system ( dH mix ), entropy of mixing of a multi-component alloy system ( dS mix ), melting temperature estimate ( T m ), valence electron concentration ( VEC ), atomic size difference ( δ ), and difference in Pauling negativities ( χ ),. While this article is limited to these typical parameters for succinctness, others can also be developed from the Alloy specifications [7] , [8] , [9] , [10] , [11] , [12] , [13] .…”

Section: Data Descriptionmentioning

confidence: 99%

Machine learning-based prediction of phases in high-entropy alloys: A data article

et al. 2021

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A systematic framework for choosing the most determinant combination of predictor features and solving the multiclass phase classification problem associated with high-entropy alloy (HEA) was recently proposed [1] . The data associated with that research paper, titled “ Machine learning-based prediction of phases in high-entropy alloys ”, is presented in this data article. This dataset is a systematic documentation and comprehensive survey of experimentally reported HEA microstructures. It contains microstructural phase experimental observations and metallurgy-specific features as introduced and reported in peer-reviewed research articles. The dataset is provided with this article as a supplementary file. Since the dataset was collected from experimental peer-reviewed articles, these data can provide insights into the microstructural characteristics of HEAs, can be used to improve the optimization HEA phases, and have an important role in machine learning, material informatics, as well as in other fields.

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Designing High Entropy Alloys with Dual fcc and bcc Solid-Solution Phases: Structures and Mechanical Properties

Cited by 43 publications

References 61 publications

Effect of Microstructural Modifications on the Corrosion Resistance of CoCrFeMo0.85Ni Compositionally Complex Alloy Coatings

Effect of Microstructural Modifications on the Corrosion Resistance of CoCrFeMo0.85Ni Compositionally Complex Alloy Coatings

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

Machine learning-based prediction of phases in high-entropy alloys: A data article

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