Topologically Close-packed Phase Formation in High Entropy Alloys: A Review of Calphad and Experimental Results

Guruvidyathri, K.; Kumar, K.C. Hari; Yeh, Jien Wei; Murty, B.S.

doi:10.1007/s11837-017-2566-5

Cited by 27 publications

(13 citation statements)

References 67 publications

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“…6,56,[58][59][60][61][132][133][134] We explained how these may be combined for direct free energy calculation, 65,85,103,135 incorporated into cluster expansions, 69,70,85,88,109,136 used as the basis for computer simulation, [84][85][86][87][88]109,120,125,127,130,131,137,138 and exploited the resulting correlation functions. 4,75,85,90,92 Finally, we related these methods to the CALPHAD approach, 5,134,[139][140][141][142][143][144][145][146][147][148] which hi...…”

Section: Summary Conclusionmentioning

confidence: 99%

Modeling the structure and thermodynamics of high-entropy alloys

Widom

2018

J. Mater. Res.

101

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Section: Summary Conclusionmentioning

confidence: 99%

Modeling the structure and thermodynamics of high-entropy alloys

Widom

2018

J. Mater. Res.

101

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“…One such approach is the CALPHAD method [25], which has proven highly effective in more conventional alloy systems. However, the underpinning thermodynamic databases are predominantly based on the phase equilibria of binary and, to a lesser extent, ternary systems and an increasing body of evidence shows that the fidelity of their predictions in higher order systems, particularly at near-equiatomic compositions, is unreliable [18,[26][27][28][29][30][31]. Furthermore, many studies of phase stability in HEAs have focused on temperatures in excess of 1000˚C [18,28,30], where single-phase solid solutions are more likely to form due to the enhanced entropic contribution to Gibbs energy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Co on the phase stability of CrMnFeCoxNi high entropy alloys following long-duration exposures at intermediate temperatures

2019

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The effect of Co on the phase stability of the CrMnFeCoxNi family of alloys, where the atomic ratio x = 0, 0.5, 1.5, has been experimentally established following 1000 hour heat treatments at 700 and 900˚C and up to 5000 hours at 500˚C. All the alloys were single phase fcc in the homogenised condition, except for CrMnFeNi which also contained bcc precipitates that remained present following exposures at 900˚C and 700˚C. The exposures at 900˚C and 700˚C also resulted in the formation of phase precipitates in the CrMnFeNi and CrMnFeCo0.5Ni alloys but not in the CrMnFeCo1.5Ni alloy. These data, in conjunction with results previously published in the literature, conclusively establish that Co stabilises the fcc matrix at elevated temperatures. However, at 500˚C, further bulk decomposition in the CrMnFeNi alloy was observed and produced a fine-scale intergrowth of a NiMn L10 phase and CrFe phase. Grain boundary precipitates were also observed following exposure at 500˚C in the CrMnFeCo0.5Ni and CrMnFeCo1.5Ni alloys. Four different phases were observed on the grain boundaries of the CrMnFeCo0.5Ni alloy (Cr carbide, , FeCo B2 and NiMn L10), whilst only two phases were found on the grain boundaries of the CrMnFeCo1.5Ni alloy (Cr carbide and NiMn L10). The experimental observations facilitated an assessment of the fidelity of current thermodynamic predictions of phase equilibria. All the phases predicted were observed experimentally and the stability fitted the experimental observations well. However, at lower temperatures, thermodynamic predictions were less consistent with experimental observations, underpredicting the extent of the B2 phase field and failing to predict the formation of the L10 phase.

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“…Zhang F. et al [ 78 ] present the results of calculating the phase diagrams of the Co-Cr-Fe-Mn-Ni, Co-Cr-Fe-Mn-Cu and Cr-Nb-Ti-V-Zr systems. Guruvidyathri et al [ 79 ] present the results of modeling phase equilibria for 52 HEAs, comparing them with experimental results. The data presented in [ 79 ] show that thermodynamic modeling can be successfully used to predict the formation of undesirable intermetallic phases (in particular, topologically close-packed phases), especially for HEAs containing transition metals.…”

Section: Heas Oxidation Productsmentioning

confidence: 99%

High-Temperature Oxidation of High-Entropic Alloys: A Review

et al. 2021

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Over the past few years, interest in high-entropic alloys (HEAs) has been growing. A large body of research has been undertaken to study aspects such as the microstructure features of HEAs of various compositions, the effect of the content of certain elements on the mechanical properties of HEAs, and, of course, special properties such as heat resistance, corrosion resistance, resistance to irradiation with high-energy particles, magnetic properties, etc. However, few works have presented results accumulated over several years, which can complicate the choice of directions for further research. This review article presents the results of studies of the mechanisms of high-temperature oxidation of HEAs of systems: Al-Co-Cr-Fe-Ni, Mn-Co-Cr-Fe-Ni, refractory HEAs. An analysis made it possible to systematize the features of high-temperature oxidation of HEAs and propose new directions for the development of heat-resistant HEAs. The presented information may be useful for assessing the possibility of the practical application of HEAs in the aerospace industry, in nuclear and chemical engineering, and in new areas of energy.

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Topologically Close-packed Phase Formation in High Entropy Alloys: A Review of Calphad and Experimental Results

Cited by 27 publications

References 67 publications

Modeling the structure and thermodynamics of high-entropy alloys

Modeling the structure and thermodynamics of high-entropy alloys

Effect of Co on the phase stability of CrMnFeCoxNi high entropy alloys following long-duration exposures at intermediate temperatures

High-Temperature Oxidation of High-Entropic Alloys: A Review

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