Exploring the compositional parameter space of high-entropy alloys using a diffusion couple approach

Keil, Tom; Bruder, Enrico; Durst, Karsten

doi:10.1016/j.matdes.2019.107816

Cited by 20 publications

(11 citation statements)

References 26 publications

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“…The idea of correlating EDX and nanoindentation data is not novel, and it has been extensively applied previously to identify individual phases of interest in the microscope for manual phase identification or to qualitatively show the relationship between an EDX line scan and the hardness fluctuations in an indentation map [27]. For samples with smooth compositional gradients like diffusion couples/multiples [25,28,29,30], quantitative correlation has also been achieved by fitting mathematical functions which describe compositional trends to a function of position to establish the relationship between indentation data and composition. Qualitative comparisons of larger-scale indentation maps with EDX [22] and EBSD [12] area scans of the same regions have also been achieved previously.…”

Section: Correlation With Edx Measurementsmentioning

confidence: 99%

Mechanical phase mapping of the Taza meteorite using correlated high‐speed nanoindentation and EDX

Wheeler

2021

Journal of Materials Research

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Meteorites have one of the most unique and beautiful microstructures, the Widmanstätten structure. This consists of large, elongated bands which form an intricate octahedral lace of crystalline metal. This structure makes meteorites an ideal case to demonstrate the capabilities of mechanical phase mapping using high-speed nanoindentation. In this work, the mechanical properties and composition of the Taza meteorite were mapped using ∼100,000 indentations to statistically determine the properties of the individual phases. Five microstructural phases were characterized in this meteorite: Kamacite, Plessite, Tetrataenite, Cloudy Zone, and Schreibersite. Mechanical phase identification was confirmed using EDX measurements, and the first direct, pointto-point correlation of EDX and large-scale indentation maps was achieved. Mechanical phase maps showed superior phase contrast to EDX in two phases. An indentation property map or a mechanical phase map using a 2D histogram was used to visualize and statistically characterize the phases and identify trends in their relationships.

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Section: Correlation With Edx Measurementsmentioning

confidence: 99%

Mechanical phase mapping of the Taza meteorite using correlated high‐speed nanoindentation and EDX

Wheeler

2021

Journal of Materials Research

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“…The purity levels of the diffusion partner elements (> 99.0%), sample preparation, heat treatment and quenching conditions can be found in Ref. [19]. The used heat treatment procedure avoids decomposition and retains the FCC phase stable of the Cantor alloy at ambient temperatures despite being potentially metastable.…”

Section: Methodsmentioning

confidence: 99%

“…For more details on the microstructure and a detailed discussion of the different diffusion profiles and the stability ranges of other phases see Ref. [19]. A light microscopy image of a representative indentation field across the complete interdiffusion zone between Cantor and Fe is shown in Fig.…”

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confidence: 99%

“…2b-d), only the FCC phase region will be considered in the further analysis. The concentrations of the respective diffusion partner elements Co or Fe can be increased substantially up to ≈ 65 at.% until a phase transition takes place [19], it is possible to evaluate SSH up to ≈ 55 at.%. As Co and Fe increase in concentration, all other constituent elements show a decreasing concentration.…”

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confidence: 99%

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Solid solution hardening in CrMnFeCoNi-based high entropy alloy systems studied by a combinatorial approach

Keil

Utt

Bruder

et al. 2021

Journal of Materials Research

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Solid solution hardening in high entropy alloys was studied for the Cantor alloy using diffusion couples and nanoindentation. We study a continuous variation of the alloying content and directly correlate the nanoindentation hardness to the local composition up to the phase boundary. The composition dependent hardness is analysed using the Labusch model and the more recent Varvenne model. The Labusch model has been fitted to experimental data and confirms Cr as the most potent strengthening element. For comparison of the experimental hardness and the predicted yield strength of the Varvenne model, a concentration-dependent strain-hardening factor is introduced to account for strain hardening during indentation, which leads to a very good agreement between experiment and model. A study of the input parameters of the Varvenne model, performed by atomistic computer simulations, shows no significant effect of fluctuations in the atomic size misfit volumes or in the local shear modulus to the computed yield strength. Graphic Abstract

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“…Few studies have explored the mechanistic design approach to tune high temperature mechanical properties of HESA. In most cases, the studies involve high temperature microstructural stabilities [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], room temperature mechanical properties [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], and the structure and fraction of the matrix phase and precipitate phase in comparison to well-known Ni-based superalloys [ 11 , 23 , 24 , 25 , 26 , 27 , 28 ]. Praveen and Kim [ 29 ] revealed that HESAs are regarded as potential materials to be used under a high temperature based on constant strain rate experiments at low temperatures and under the assumption of diffusion being sluggish.…”

Section: Introductionmentioning

confidence: 99%

A Review on the High Temperature Strengthening Mechanisms of High Entropy Superalloys (HESA)

Joele

Matizamhuka

2021

Materials

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The studies following HEA inceptions were apparently motivated to search for single-phase solid solution over intermetallic phases, accordingly made possible by the concept of high configurational entropy. However, it was realised that the formation of intermetallic phases in HEAs is prevalent due to other criterions that determine stable phases. Nonetheless, recent efforts have been directed towards attributes of microstructural combinations. In this viewpoint, the techniques used to predict microstructural features and methods of microstructural characterisation are elucidated in HESA fields. The study further analyses shortcomings regarding the design approaches of HESAs. A brief history is given into how HESAs were developed since their birth, to emphasize the evaluation techniques used to elucidate high temperature properties of HESAs, and the incentive thereof that enabled further pursuit of HESAs in the direction of optimal microstructure and composition. The theoretical models of strengthening mechanisms in HEAs are explained. The impact of processing route on the HESAs performance is analysed from previous studies. Thereafter, the future of HESAs in the market is conveyed from scientific opinion. Previous designs of HEAs/HESAs were more based on evaluation experiments, which lead to an extended period of research and considerable use of resources; currently, more effort is directed towards computational and theoretical methods to accelerate the exploration of huge HEA composition space.

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Exploring the compositional parameter space of high-entropy alloys using a diffusion couple approach

Cited by 20 publications

References 26 publications

Mechanical phase mapping of the Taza meteorite using correlated high‐speed nanoindentation and EDX

Mechanical phase mapping of the Taza meteorite using correlated high‐speed nanoindentation and EDX

Solid solution hardening in CrMnFeCoNi-based high entropy alloy systems studied by a combinatorial approach

A Review on the High Temperature Strengthening Mechanisms of High Entropy Superalloys (HESA)

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