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Young's modulus is essential for the design and production of the alloys. Thus, we proposed a MGI (Materials Genome Initiative)-oriented strategy for the high-throughput development of Young's modulus databank in the single-phase alloys. In this study, 17 diffusion couples of the bcc Ti-rich Ti-Nb-Zr, Ti-Nb-Cr and Ti-Nb-Zr-Cr systems annealed at 1273 K for 25 h were experimentally prepared. Subsequently, the composition-dependent Young's moduli and hardness in the bcc Ti-rich Ti-Nb-Zr-Cr system were determined by combining the nanoindentation technique and the electron probe micro analysis (EPMA). Moreover, on the basis of the presently obtained experimental data, the Young's modulus databank in the bcc Ti-Nb-Zr-Cr system were established by means of the CALPHAD (CALculation of PHAse Diagrams) approach. Finally, the Ti-22.6 at.% Nb-30 at.% Zr-3.8 at.% Cr alloy was designed from the Young's modulus databank and verified by using the nanoindentation and cytotoxicity tests. The results reveal that the present MGI-oriented strategy with the combination of the high-throughput measurements and the CALPHAD approach is a very effective method to accelerate the design/development of novel bio-Ti alloys., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Balancing the hardness and electrical conductivity of copper alloys within complex compositions and processes poses a formidable challenge. This study proposes a strategy combining machine learning with the Pareto front techniques to identify optimal combinations of composition and processing for Cu-xTi (1.5 ≤ x ≤ 5.4, in wt.%) alloys. Through thermodynamic calculations, precipitation simulations, and experimental characterizations, the microstructural evolution of β'-Cu4Ti precipitates in the designed alloys was explored. The interpretability and predictability of the machine learning model played a crucial role in understanding impact of complex alloy compositions and processing on the evolution of properties, thereby guiding the design of Cu-Ti alloys towards improved attributes. A novel strategy integrating machine learning with Pareto front is proposed for alloy design, facilitating the rapid screening of Cu-Ti alloys that exhibit superior hardness and electrical conductivity simultaneously. [ABSTRACT FROM AUTHOR]

Scandium is the best alloying element to improve the mechanical properties of industrial Al-Si-Mg casting alloys. Most literature reports devote to exploring/designing optimal Sc additions in different commercial Al-Si-Mg casting alloys with well-defined compositions. However, no attempt to optimize the contents of Si, Mg, and Sc has been made due to the great challenge of simultaneous screening in high-dimensional composition space with limited experimental data. In this paper, a novel alloy design strategy was proposed and successfully applied to accelerate the discovery of hypoeutectic Al-Si-Mg-Sc casting alloys over high-dimensional composition space. Firstly, high-throughput CALculation of PHAse Diagrams (CALPHAD) solidification simulations of ocean of hypoeutectic Al-Si-Mg-Sc casting alloys over a wide composition range were performed to establish the quantitative relation 'composition-process-microstructure'. Secondly, the relation 'microstructure-mechanical properties' of Al-Si-Mg-Sc hypoeutectic casting alloys was acquired using the active learning technique supported by key experiments designed by CALPHAD and Bayesian optimization samplings. After a benchmark in A356-xSc alloys, such a strategy was utilized to design the high-performance hypoeutectic Al-xSi-yMg alloys with optimal Sc additions that were later experimentally validated. Finally, the present strategy was successfully extended to screen the optimal contents of Si, Mg, and Sc over high-dimensional hypoeutectic Al-xSi-yMg-zSc composition space. It is anticipated that the proposed strategy integrating active learning with high-throughput CALPHAD simulations and key experiments should be generally applicable to the efficient design of high-performance multi-component materials over high-dimensional composition space. [ABSTRACT FROM AUTHOR]

Nanoparticle strengthening provides a crucial basis for developing high-performance structural materials with potentially superb mechanical properties for structural applications. However, the general wisdom often fails to work well due to the poor thermal stability of nanoparticles, and the rapid coarsening of these particles will lead to the accelerated failures of these materials especially at elevated temperatures. Here, we demonstrate a strategy to achieve ultra-stable nanoparticles at 800~1000 °C in a Ni59.9-xCoxFe13Cr15Al6Ti6B0.1 (at.%) chemically complex alloy, resulting from the controllable sluggish lattice diffusion (SLD) effect. Our diffusion kinetic simulations reveal that the Co element leads to a significant reduction in the interdiffusion coefficients of all the main elements, especially for the Al element, with a maximum of up to 5 orders of magnitude. Utilizing first-principles calculations, we further unveil the incompressibility of Al induced by the increased concentration of Co plays a critical role in controlling the SLD effect. These findings are useful for providing advances in the design of novel structural alloys with extraordinary property-microstructure stability combinations for structural applications. Nanoparticle strengthening provides a crucial basis for developing high-performance materials, which often fails to work due to poor thermal stability. Here, the authors achieve thermally stable nanoparticles at 800~1000 °C in chemically complex alloys via controllable sluggish lattice diffusion. [ABSTRACT FROM AUTHOR]

Ever‐increasing demands for superior alloys with improved high‐temperature service properties require accurate design of their composition. However, conventional approaches to screen the properties of alloys such as creep resistance and microstructural stability cost a lot of time and resources. This work therefore proposes a novel high throughput–based design strategy for high‐temperature alloys to accelerate their composition selections, by taking Ni‐based superalloys as an example. A numerical inverse method is used to massively calculate the multielement diffusion coefficients based on an accurate atomic mobility database. These coefficients are subsequently employed to refine the physical models for tuning the creep rates and structural stability of alloys, followed by unsupervised machine learning to categorize their composition and determine the range of the composition with optimal performance. By using a strict screening criterion, two sets of composition with comprehensively optimal properties are selected, which is then validated by experiments. Compared with recent data‐driven methods for materials design, this strategy exhibits high accuracy and efficiency attributed to the high‐throughput multicomponent diffusion couples, self‐developed atomic mobility database, and refined physical models. Since this strategy is independent of the alloy composition, it can efficiently accelerate the development of multicomponent high‐performance alloys and tackle challenges in discovering novel materials. [ABSTRACT FROM AUTHOR]

This study aims to incorporate a big dataset of composition profiles of fcc AlCoCrFeNi alloys, in addition to those of the related subsystem, to develop a self-consistent kinetic description for quinary high-entropy alloys. The latest feature of the HitDIC (High-throughput Determination of Interdiffusion Coefficients) code was adopted in a high-throughput and automatic manner for accommodating a dataset of composition profiles with up to 87 diffusion couples. A good convergence for the optimization process was achieved, while satisfactory results regarding the composition profiles and previously evaluated diffusion properties were obtained. Here, we present an investigation into the elemental effect of Al towards interdiffusion and tracer diffusion, and their potential effect on creep and precipitation processes. [ABSTRACT FROM AUTHOR]

Interstitial atom doping can enhance mechanical properties and phase structure, but its impact on corrosion resistance is not well-researched. This study investigated the influence of carbon-doping on the microstructure and corrosion resistance of CoCrFeNi high-entropy alloys. The results show that alloy doped with a moderate carbon content (C0.3 alloy) have the best corrosion resistance in 3.5 wt% NaCl solution, while alloys with carbides (M 7 C 3) show poor corrosion resistance. The stability, semiconductive property, and composition of the passivation films were characterized to reveal the corrosion mechanisms. These findings provide a theoretical basis for the development and application of carbon-doped high-entropy alloys. • The corrosion mechanisms of CoCrFeNi-C x HEAs was studied. • Doping with moderate amounts of carbon can improve the corrosion resistance. • The alloys containing M 7 C 3 carbides undergo galvanic coupling corrosion. • The passivation film properties of alloys (C0.1, C0.3, C0.9) were investigated. [ABSTRACT FROM AUTHOR]

In this article, the transformation laws of microstructural formation, phase evolution, electrothermal and magnetic properties in as-cast and annealed CrFeNiTix compositionally complex alloys have been systematically investigated. The result showed that annealed CrFeNiTix alloys consisted of the [Fe, Cr] solid solution (BCC), CrFeNi solid solution (FCC) and rich-(Ni, Ti) intermetallic compound (HCP). Transmission electron microscope indicated that the rich-(Ni, Ti) intermetallic nanoparticles, which were distributed on the disordered BCC [Fe, Cr] solid solution of CrFeNiTi0.4 alloy matrix, grew and transformed. For CrFeNiTix alloys, the electrical resistivity increased with Ti addition and increase of thermal conductivity was presented with decreasing Ti content. In addition, annealed treatment could decrease electrical resistivity but increased thermal conductivity of as-cast alloys. Moreover, the CrFeNiTix alloys exhibited typical soft-magnetic characteristic indicated by low coercivity. The saturation magnetization of as-cast and annealed CrFeNiTix alloys rose at the beginning, then reduced with the addition of Ti content. It suggested that CrFeNiTix alloys with major solid solutions showed the better soft-magnetic properties than those with major intermetallic compound, which is influenced by the crystal structure, phase boundaries and defects. [ABSTRACT FROM AUTHOR]

In this paper, eight solid-state diffusion couples in fcc ternary Cu-Ni-Al alloys at 1073, 1173 and 1273 K were prepared, and the corresponding composition profiles were measured with an electron probe microanalyzer (EPMA) technique. Based on the measured composition profiles and HitDIC software, a set of reliable atomic mobility descriptions in the fcc Cu-Ni-Al system were directly established, from which the composition- and temperature-dependent interdiffusion coefficient matrices were evaluated. Then, the three-dimensional (3D) main interdiffusivity surfaces for fcc Cu-Ni-Al systems were constructed. The diffusion rate of Al is faster than that of Ni. Both the main interdiffusivities of Al and Ni increase with the increase of Al concentration but decrease with Ni concentration. The reliability of the evaluated interdiffusivities was first validated by reproducing the measured composition profiles and interdiffusion fluxes. After that, the interdiffusivities and corresponding uncertainties at intersection points of diffusion couples were evaluated by using the Matano–Kirkaldy method combined with distribution functions. Especially all the interdiffusion coefficients estimated from the present mobility parameters are within the bounds of the uncertainties, which further quantitatively verified the reliability of the present mobility descriptions. The accuracy of the as-determined mobility is further highlighted via combining with the reported thermodynamic descriptions, which enables an accurate prediction of the volume of Ni3Al precipitates in the Cu-Ni-Al alloy during artificial aging. The present work indicates that with the accurate thermodynamic as well as boundary mobility descriptions, reliable ternary mobility descriptions can be achieved by combining the diffusion couple experiments with the HitDIC modeling. [ABSTRACT FROM AUTHOR]

The study on the temperature-dependent kinetic behavior of intermetallic compounds (IMCs) in Mg–Al–Zn (AZ) series alloy system is important since its close interrelation with the microstructure evolution under various alloying conditions as well as the T-dependent performance. However, there is a very lack of experimental study on the diffusion kinetics of the ternary IMCs in the AZ series alloy systems. The current work combines the diffusion couple technique and numerical inverse method to investigate the T-dependent kinetic coefficients, i.e., the parabolic growth constant (PGC) and interdiffusion coefficients, for ϕ-Mg5Al2Zn2 ternary IMC in the Mg–Al–Zn alloy system. The Arrhenius formula of both PGC and main interdiffusivities is obtained, i.e., ϕ k p = 5.48 × 10 - 5 exp 120010 RT m2/s, ϕ D ~ MgMg Al = 3.48 × 10 - 10 exp 50420 RT m2/s and ϕ D ~ ZnZn Al = 2.87 × 10 - 7 exp 91440 RT m2/s, based on which a numerical reproduction of the experimentally determined IMC growth is performed for verification. By comparing the current experimental and calculation results, the rate-controlling factor of the temperature-dependent diffusion growth of ϕ ternary IMC in the Mg–Al–Zn system is further discussed. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of solidification behavior of Mg–Al–Zn–Bi alloys is necessary for designing novel casting Bi-modified AZ alloys. In this paper, 21 Mg–Al–Zn–Bi alloys were prepared to investigate the phase constituents, morphologies, grain sizes and area fractions of precipitates in as-cast microstructures, as well as their phase transition temperatures and solidification paths by using X-ray diffraction, scanning electron microscopy, optical microscopy and differential scanning calorimetric techniques. It was found that the Bi addition leads to the formation of α-Mg3Bi2 phase, which became coarse flake as Bi content increased. Besides, the Bi addition can modify the morphology of eutectic γ-Al12Mg17 phase and refine the grain size of primary phase. Moreover, the measured area fractions of precipitates increased steadily as Bi content increased, which were comparable with the model-predicated values. After that, the calculated liquidus projections in the Mg-rich corner of Mg–Al–Zn–Bi quaternary system were employed for demonstrating the effects of Bi addition on the solidification sequences. Additionally, the phase transition temperatures predicted via Scheil solidification simulations agreed well with measured values. The present work indicated that the combination of experimental investigations and thermodynamic calculations can serve as an efficient method to obtain accurate and comprehensive solidification behavior of Bi-modified Mg–Al–Zn alloys. [ABSTRACT FROM AUTHOR]

The design of advanced functional materials with customized properties often requires the use of an alloy. This approach has been used for decades, but only recently to create van der Waals (vdW) alloys for applications in electronics, optoelectronics, and thermoelectrics. A route to engineering their physical properties is by mixing isoelectronic elements, as done for the SnSe2(1−x)S2x alloy. Here, by experiment and first‐principles modeling, it is shown that the value of x can be adjusted over a wide range, indicating good miscibility of the SnS2 and SnSe2 compounds. The x‐dependence of the indirect bandgap energy from Eind = 1.20 eV for SnSe2 to Eind = 2.14 eV for SnS2, corresponds to a large bowing coefficient b ≈ 1 eV, arising from volume deformation and charge exchange effects due to the different sizes and orbital energies of the S‐ and Se‐atoms. This also causes composition‐dependent phonon energy modes, electron–phonon interaction, and temperature dependence of Eind. The alloys are exfoliable into thin layers with properties that depend on the composition, but only weakly on the layer thickness. This work shows that the electronic and vibrational properties of the SnSe2(1−x)S2x alloy and its thin layers provide a versatile platform for development and exploitation. [ABSTRACT FROM AUTHOR]

The solidification diagrams of A357-Sc, A360-Sc and A380-Sc were constructed on the basis of the Scheil-Gulliver solidification simulations and previously well-established thermodynamic database, from which the optimal additional amounts of Sc in Al-Si-(Mg) series hypoeutectic alloys were designed for the best mechanical properties, and then validated by the microstructure observation and mechanical property test. With the designed levels of Sc addition, the eutectic (Si) particles were well refined and the primary (Al) grains evolved from the elongated ones to the equiaxial ones. The primary/eutectic (Al)/AlSc 2 Si 2 interfaces were determined using the high resolution transmission electron microscope technique to be partially coherent in three dimensions. Furthermore, it was finally understood that the grain refinement of eutectic (Si) and the occurrence of partially coherent AlSc 2 Si 2 phase with (Al) matrix due to the addition of Sc allow the high density of dislocations to accommodate at grain boundary, and thus improve the mechanical strengths and ductility of Al-Si-(Mg) cast alloys. Image 1 • The optional composition of A357-Sc, A360-Sc and A380-Sc alloys were designed. • The (Al)/AlSc 2 Si 2 interfaces were determined to be partially coherent. • Dislocations accommodate at grain boundary of refined (Si) and AlSc 2 Si 2. • Mechanisms of improvement in strengths and ductility of the alloys were proposed. [ABSTRACT FROM AUTHOR]

In this paper, the effect of different cooling media, i.e., water quenching, air cooling and furnace cooling, after solid solution treatment on the microstructure and yield strength of Ni-15.9Al at. pct alloy during aging at 800 °C was first experimentally investigated. It was found that the morphologies and the particle sizes of γ′ precipitates as well as the yield strength of the target alloys during aging were strongly affected by the cooling media after solid solution. The yield strengths of the target alloys after aging with water quenching and air cooling after solid solution are similar, and higher than that with furnace cooling. By further considering the cost and environment factors, the air cooling after solid solution treatment was thus proposed for industry alloys. Meanwhile, a quantitative simulation of the microstructure evolution in the target alloy during aging was realized by means of phase-field modeling coupling with CALPHAD thermodynamic and atomic mobility descriptions. Moreover, the extracted experimental microstructure of the Ni-15.9Al at. pct alloy with air cooling after solid solution was inputted as the initial microstructure of phase-field simulation. Subsequently, the microstructural features obtained from both phase-field simulations and experiments were imported into the strengthening models to predict the evolution of the total yield strengths during aging. The model-predicted total yield strengths in the Ni-15.9Al at. pct alloy were found to be in the excellent agreement with the experimental results from the tensile tests. [ABSTRACT FROM AUTHOR]

• The carburized coating was fabricated through SPS process. • The coating contains two types of carbide precipitates (M 7 C 3 and M 23 C 6). • The hardness and wear resistance of the coating were greatly improved. Carburization by spark plasma sintering process is successfully employed in surface modification of Al 0.1 CoCrFeNi high entropy alloy. The carburized coating has a double-layer structure and contains two types of carbide precipitates (M 7 C 3 and M 23 C 6). The surface Vickers hardness shows a gradient decreasing trend, and the highest hardness is about three times that of the matrix. Nanoindentation tests are performed to investigate the nanoscale mechanical properties of different phases at different distances from the coating surface. The wear resistance of carburized coating is also assessed based on the nanoindentation results. This research results indicate that the hardness and wear resistance of the carburized coating have been greatly improved. [ABSTRACT FROM AUTHOR]

In this paper, an Open-source code for Interfacial Energy Calculation (OpenIEC, https://github.com/openiec) was developed by following Kaptay's models (Acta Mater 60(19):6804–6813, 2012; J Mater Sci 53(5):3767–3784, 2018. 10.1007/s10853-017-1778-y). The coupling with the CALculation of PHAse Diagram thermodynamic and molar volume databases was facilitated in OpenIEC for providing the necessary thermodynamic information. With OpenIEC, the temperature- and composition-dependent interfacial energies in alloys with any arbitrary number of components can be conveniently evaluated. In order to demonstrate the applicability and validity of OpenIEC, the benchmark tests in several model alloys in Ni and Al alloys were carried out, and the calculated interfacial energies were found to be in good agreement with the literature data. After that, the OpenIEC was applied to predict the temperature- and composition-dependent interfacial energies of coherent γ/γ' interfaces in two Ni-based superalloys, including ternary Ni–Al–Cr and quaternary Ni–Al–Cr–Re alloys, as well as the temperature- and composition-dependent solid/liquid interfacial energies in Ni–Al–Cr and Al–Cu–Li alloys. [ABSTRACT FROM AUTHOR]

Abstract Diffusion behaviors of Rh, Ta, W, Re, Os, and Ir in ternary γ′-Ni 3 Al alloys were investigated at 1373–1473 K using solid-solid single-phase diffusion couples together with the recently developed HitDIC software. The temperature- and concentration-dependent ternary interdiffusivities in Ni 3 Al-X (X = Rh, Ta, W, Re, Os, and Ir) were determined from the experimental concentration profiles, and also fully validated. After that, a thorough comparison among the interdiffusivities in γ′ Ni–22.9 at% Al–0.1 at% X (X = Ti, V, Cr, Fe, Co, Ni, Nb, Mo, Ru, Rh, Ta, W, Re, Os, Ir and Pt) alloys at 1373–1473 K was then conducted, from which it can be concluded that W exhibits the lowest interdiffusivities in γ′-Ni 3 Al alloy, followed by Ta. It is finally suggested that addition of W and Ta in γ′ phase can retard the coarsening of γ′ phase and stabilize the microstructure of the nickel-based single crystal superalloys in terms of the diffusion coefficient. Highlights • Interdiffusivities in γ′ Ni–Al–X (X = Rh, Ta, W, Re, Os, Ir) alloys were determined. • Interdiffusivities in γ′ Ni–22.9 at% Al–0.1 at% X alloys at 1373–1473 K were compared. • W possesses the lowest diffusion rate in Ni 3 Al, followed by Ta. [ABSTRACT FROM AUTHOR]

• A new AlCrFeMnNi 2 HEA with a unique sunflower-like eutectic structure was designed. • The HEA has excellent comprehensive mechanical properties. • Coherent interface and bimodal distribution of B2 phase lead to good properties. Although most BCC-based high-entropy alloys have high strength and excellent high temperature mechanical properties, their low plasticity greatly limit their application. It is a new challenge to develop new BCC-based high-entropy alloys with excellent combination of high strength and plasticity. In this study, we prepare a new BCC/B2 AlCrFeMnNi 2 high-entropy alloy with a unique sunflower-like eutectic microstructure. This alloy has a high yield strength of 1206 MPa, a high fracture strength of 3437 MPa and large compressive plastic strain of 37.5%. The excellent compressive mechanical properties are superior to many other BCC/B2 high-entropy alloys. These properties can be attributed to its unique microstructure consisting of coherent interface between BCC and B2 phase and the bimodal distribution of the B2 precipitates. Our results can provide a meaningful reference for improving the plasticity of BCC-based high entropy alloys. [ABSTRACT FROM AUTHOR]

In this report, a combination of the diffusion multiple technique and the recently developed pragmatic numerical inverse method was employed for a high-throughput determination of interdiffusivity matrices in Co-Cr-FeMn-Ni high-entropy alloys (HEAs). Firstly, one face-centered cubic (fcc) quinary Co-Cr-Fe-Mn-Ni diffusion multiple at 1373 K was carefully prepared by means of the hot-pressing technique. Based on the composition profiles measured by the field emission electron probe micro analysis (FE-EPMA), the composition-dependent interdiffusivity matrices in quinary Co-Cr-Fe-Mn-Ni system at 1373 K were then efficiently determined using the pragmatic numerical inverse method. The determined interdiffusivities show good agreement with the limited results available in the literature. Moreover, the further comparison with the interdiffusivities in the lower-order systems indicates the sluggish diffusion effect in Co-Cr-Fe-Mn-Ni HEAs, which is however not observed in tracer diffusivities. In order for the convenience in further analysis, a generalized transformation relation among interdiffusivities with different dependent components in multicomponent systems was finally derived. [ABSTRACT FROM AUTHOR]

The pressure-volume ( P- V) relationship of the AlCoCrCuFeNi high-entropy alloy (HEA) at room temperature has been studied using in situ high-pressure energy-dispersive x-ray diffraction with synchrotron radiation at high pressures. The equation of state of the AlCoCrCuFeNi HEA is determined by the calculation of the radial distribution function. The experimental results indicate that the HEA keeps a stable face-centered-cubic + body-centered-cubic structure in the experimental pressure range from 0 GPa to 24 GPa. [ABSTRACT FROM AUTHOR]

The influence of composition and temperature on the atomic mobilities of Al, Ni and Fe in the bcc_A2 and bcc_B2 Al–Ni–Fe phases was investigated based on a recently developed phenomenological model, together with the newly published thermodynamic description. The experimental interdiffusivities and tracer diffusivities of Ni and Fe in various Al–Ni–Fe alloys available in the literature were critically evaluated. The calculated diffusivities can reasonably reproduce the experimental ones. The calculated iso-diffusivity lines in the B2 phase show a minimum around the quasi-binary section at 50 at.% Al for the main diffusivities of both Al and Ni, while for the cross diffusivities of Al and Ni, they show significantly different characteristics when changing from negative to positive values. The obtained atomic mobilities were further used to predict the concentration profiles and diffusion paths in a variety of B2 Al–Ni–Fe diffusion couples. The comparison reveals the importance of full diffusion-distance measurement for the accurate determination of diffusion coefficients. [ABSTRACT FROM AUTHOR]

The amorphous ZrCu alloy ribbon was prepared and annealed in a high vacuum furnace at 645 K (372 °C) for different times. It was found that the main crystallization phases in the alloy ribbon are CuZr and CuZr. The grains of CuZr show special orientation relationships. The grains in opposite dendrites show the same orientation, and adjacent dendrites behave as a twinlike orientation with a (103) twin plane. The CuZr with a superstructure is discovered in annealed ZrCu metallic glasses. [ABSTRACT FROM AUTHOR]

By combining solid/solid diffusion couples and the electron probe microanalysis technique, the interdiffusivities in fcc Ni-Cu-Si alloys at 1373 K were experimentally determined via the Matano-Kirkaldy method in the present work. Based on the reliable thermodynamic description of fcc phase in the Ni-Cu-Si system available in the literature as well as the ternary diffusion coefficients measured in this work, the atomic mobilities in fcc Ni-Cu-Si alloys were assessed by utilizing the DICTRA (DIffusion Controlled TRAnsformation) software package. The calculated interdiffusivities based on the assessed atomic mobilities agree well with all the experimental data. The reliability of the presently obtained atomic mobilities was further verified by comprehensive comparisons between different kinds of model-predicted diffusion properties and the measured data, including the concentration penetration profiles, interdiffusion flux profiles, and diffusion paths. [ABSTRACT FROM AUTHOR]

In this paper, a general and effective strategy was first developed to maintain the CALPHAD atomic mobility database of multicomponent systems, based on the pragmatic numerical method and freely accessible HitDIC software, and then applied to update the atomic mobility descriptions of the hcp Mg–Al–Zn, Mg–Al–Sn, and Mg–Al–Zn–Sn systems. A set of the self-consistent atomic mobility database of the hcp Mg–Al–Zn–Sn system was established following the new strategy presented. A comprehensive comparison between the model-predicted composition–distance profiles/inter-diffusivities in the hcp Mg–Al–Zn, Mg–Al–Sn, and Mg–Al–Zn–Sn systems from the presently updated atomic mobilities and those from the previous ones that used the traditional method indicated that significant improvement can be achieved utilizing the new strategy, especially in the cases with sufficient experimental composition–distance profiles and/or in higher-order systems. Furthermore, it is anticipated that the proposed strategy can serve as a standard for maintaining the CALPHAD atomic mobility database in different multicomponent systems. [ABSTRACT FROM AUTHOR]

Abstract: This paper performs an extensive investigation for the complex Al–Fe–Ni system via key experiments and thermodynamic modeling. 12 decisive alloys are prepared with a desire to provide accurate phase relationships needed for the refinement of this ternary phase diagram. The order/disorder transitions between disordered and ordered phases as well as between disordered and ordered phases are described as a two-sublattice model. The calculations indicate that the disordered and ordered phases can be described with a single equation. A self-consistent thermodynamic description of the Al–Fe–Ni system is obtained by considering the huge amount of experimental data from the literature and the present work. Most of the experimental data can be satisfactorily reproduced by the present modeling. The complete liquidus projection and reaction scheme are also presented. [Copyright &y& Elsevier]

Abstract: The Co–Si system is investigated via experiment and modeling. Based on the critical evaluation of the phase diagram data available in the literature, one key Co/Si diffusion couple and eight decisive alloys are prepared. The diffusion couple, which is annealed at 1323.15 K for 8 days, is first examined by scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), and then by electron probe microanalysis (EPMA) to determine homogeneity ranges of the phases. The alloys, which are annealed at 1373.15 K for 3 days and then water-quenched, are analyzed using X-ray diffraction (XRD), optical microscopy, differential thermal analysis (DTA), and EPMA. The thermodynamic optimization for the Co–Si system is then conducted by using the assessed literature data and the present experimental data. For and , the magnetic contribution to the Gibbs energy is taken into account. The sublattice model is employed to describe (the high-temperature form of the Co2Si phase), (the low-temperature form of the Co2Si phase) and CoSi. A set of self-consistent thermodynamic parameters is finally obtained. Comprehensive comparisons show that the calculated phase diagram and thermodynamic properties agree well with the experimental ones. Significant improvements have been made, compared with the previous assessments. [Copyright &y& Elsevier]

In this study, we systematically studied the high pressure polymorphism phase transition process in the Fe 40 Mn 40 Co 10 Cr 10 multi-principal element alloy through the hexahedron pressure equipment and the high pressure synchrotron angle-dispersive x-ray diffraction technique. A mixture of face-center cubic (fcc) + hexagonal close packed (hcp) nanolaminate structure was observed for the samples after high pressure treatment at 5 GPa, through the hexahedron pressure equipment. Especially, the hcp lath interaction structure with a new secondary hcp phase at the intersection zone was discovered in the sample. Transmission Electron Microscopy (TEM) analysis revealed that the transition from fcc to hcp was accomplished by the glide of Shockley partial dislocations. In addition, the in-situ synchrotron angle-dispersive x-ray diffraction technique was carried out to detect the phase transition process of the Fe 40 Mn 40 Co 10 Cr 10 alloy up to 40.4 GPa. The lattice constant, atomic volumes, bulk modulus, and volume fraction of the fcc and hcp phase were obtained during compression and decompression. These results can expand our understanding of the structure evolution and properties of multi-principal element alloys under extreme conditions such as high pressure, which is contribute to the development of new metastable structural materials. • The polymorphism phase transition was observed in the non-equiatomic Fe 40 Mn 40 Co 10 Cr 10 HEA. • Hexahedron pressure equipment and high pressure synchrotron angle-dispersive XRD technique were used to explore the phase transition. • A dual-phase HEA with enhanced tensile property was obtained after high pressure treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pareto optimal driven automation framework was used for 3D quantitative simulation. • Newly developed exploration strategies and different algorithms were examined. • C–H simulated microstructure favorably coincided with the experimental results. Phase separation occurring via spinodal decomposition is considered responsible for the "475 °C embrittlement" in Fe-Cr alloys. It is thus critical to gain quantitative descriptions of the microstructure evolution in Fe-Cr alloys during spinodal decomposition. However, quantitative in-situ or ex-situ experimental observations of spinodal decomposition processes in Fe-Cr alloys are generally scarce, and most numerical simulations are still not completely quantitative. In this paper, the Cahn-Hilliard simulations regarding spinodal decomposition in Fe-Cr alloys were systematically summarized. We employed the Pareto optimal driven automation framework to perform quantitative three-dimensional Cahn-Hilliard simulations of microstructure evolution in Fe-Cr alloys during spinodal decomposition process. The sampling efficiency of newly developed exploration strategies and different searching algorithms were extensively examined and discussed. The uncertain material/model parameters of the Cahn-Hilliard model were derived by considering multiple characteristic microstructure data. The remarkable consistency between the simulated multiple microstructure characteristics and the experimental observations further validated the generalization ability of the parameters set. It shows a massive potential that the parameters set can quantitatively simulate microstructure evolution in Fe-Cr alloys under various conditions. Furthermore, the capability of the Pareto optimal driven automation framework was reconfirmed by its successful application to Fe-Cr alloys. [ABSTRACT FROM AUTHOR]

An approach was proposed to obtain a reasonable thermodynamic description of a thermal vacancy in the metastable disordered body centered cubic (bcc_A2) phase, which had been consistently ignored in previous thermodynamic assessments. The present approach was first applied to obtain the thermodynamic descriptions for pure metastable bcc Ni and Zn, and then in the binary Ni-Zn system. The thermodynamic descriptions for both the metastable disordered bcc_A2 phase and the stable ordered bcc_B2 β phases in the Ni-Zn binary system were updated based on the corresponding experimental equilibria. With these updated thermodynamic descriptions, several drawbacks, including the multiple solutions for thermal vacancy concentrations and the artificial phase boundaries in previous assessments, can be avoided. Moreover, the calculated phase boundaries and invariant reactions related to the β phase agree well with the experimental data. [ABSTRACT FROM AUTHOR]

In this paper, we developed a general approach to quantify the uncertainties of interdiffusion coefficients in binary, ternary and multicomponent systems evaluated using the Boltzmann-Matano and related other methods together with the distribution functions. Various sources of errors from both experimental and calculation procedures and their propagation were fully considered and quantified in the finally obtained interdiffusion coefficients. Benchmark tests in hypothetical binary systems with three types of the preset D-c relations and three noise levels were utilized to validate the presently proposed approach, which was then successfully applied in the practical binary, ternary and high-entropy alloys. The comprehensive comparison between the presently calculated interdiffusivities in different alloys with the literature data indicated that the integration of Matano-based methods, the distribution function and the present approach represents a general ensemble solution for evaluation of the reliable interdiffusion coefficients and their uncertainties. Further discussion indicates that the accurate interdiffusion coefficients with reliable uncertainty are the "cornerstone" for the subsequent analysis on diffusion properties, i.e., the sluggish diffusion in high-entropy alloys, and the development of high-quality atomic mobility databases, and the impurity diffusion coefficients with uncertainties can be directly retrieved from the evaluated composition-dependent binary interdiffusion coefficients. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this paper, a critical review of all the experimental diffusivities in fcc Ni−X (X = Rh, Ta, W, Re, and Ir) systems available in the literature was first performed. The four end-member parameters corresponding to self- and impurity diffusivities in fcc Rh, Ta, W, Re and Ir in Ni−X (X = Rh, Ta, W, Re, and Ir) systems were then evaluated based on the literature data, first-principles results and semi-empirical equations. After that, the atomic mobilities for fcc Ni−X (X = Rh, Ta, W, Re, and Ir) systems were assessed by using DICTRA (DIffusion-Controlled TRAnsformations) software package on the basis of the critically reviewed diffusivities and the corresponding thermodynamic descriptions. The excellent agreement between various calculated diffusion properties, including impurity/tracer diffusivities and interdiffusivities, and the experimental data was obtained. Finally, the reliability of the currently obtained atomic mobilities in fcc Ni−X (X = Rh, Ta, W, Re, and Ir) alloys were validated by comparing the model-predicted concentration profiles of 24 groups of fcc Ni/Ni−X (X = Rh, Ta, W, Re, and Ir) diffusion couples with the experimental data. The presently obtained atomic mobility descriptions for fcc Ni−X (X = Rh, Ta, W, Re, and Ir) systems are to be merged into the atomic mobility database for nickel-based superalloys. • Self- and impurity diffusivities were evaluated based on first-principles results and semi-empirical equations. • The atomic mobilities of fcc Ni-rich Ni–X (X = Rh, Ta, W, Re, and Ir) alloys were constructed. • Comparisons between the calculated and experimental data show the mobility parameters lead to a better agreement. • To further verify the accuracy of the obtained mobility parameters in this work, the concentration curves are reproduced. [ABSTRACT FROM AUTHOR]

Abstract In this study, the microstructures and mechanical properties of CoFeMnNiTi x (where the molar ratio (x) is 0, 0.25, 0.5, and 0.75) high entropy alloys were examined. Both the CoFeMnNi and CoFeMnNiTi 0.25 alloys exhibit a simple face-centered cubic (FCC) solid-solution structure, whereas the CoFeMnNiTi 0.5 and CoFeMnNiTi 0.75 alloys exhibit a dual-phase structure consisting of a FCC solid-solution and a Laves phase. The Laves phase is identified as a Fe 2 Ti type and has a hexagonal C14 structure. The volume fraction of the Laves phase increases with increasing the Ti content. The Ti content has an obvious effect on the mechanical properties of the alloys. The yield strength and hardness of the alloys improve but ductility simultaneously decreases as the Ti content increases. The CoFeMnNiTi 0.5 alloy has a good balance of both strength and ductility, and is superior to other similar CoCrFeNi-based and CoCrCuFeNi-based alloys. The yield strength, fracture strength and fracture strain of the CoFeMnNiTi 0.5 alloy can reach 803 MPa, 2300 MPa and 34%, respectively. In addition, nanoindention tests show that the nanohardness value of the Laves phase is almost two times of the FCC phase, and the elastic modulus of the Laves phase is higher than that of the FCC phase in the current alloy system. By measuring the first pop-in event, the deformation behaviors of FCC and the Laves phases of the CoFeMnNiTi 0.5 alloy were investigated. [ABSTRACT FROM AUTHOR]

This short communication presents a high-throughput experimental approach for screening multicomponent alloy compositions with optimal mechanical properties using two-step diffusion multiple, and its successful application in Al–Co–Cr–Fe–Ni–Ti high-entropy superalloys. The relation "composition-microstructure-microhardness" is then established, from which the compositions with optimal microhardness/tensile properties are efficiently screened out and finally validated. [ABSTRACT FROM AUTHOR]

In this work, a prediction model, which can be used to reveal the corrosion mechanism and behavior of Mg-RE-Ni alloys, was successfully developed with machine learning. The model is constructed based upon the microstructure parameters of LPSO phase, and the accuracy of the prediction model is greater than 93 %. The results agree well with the literature when it is used to study the relationship of composition-structure-corrosion behavior of Mg-RE-Ni alloys. This work solves the shortcomings of experimental studies, which provide a route to quantitively analyze and reveal the corrosion mechanism of Mg-RE-Ni alloys. • The microstructure characteristics of LPSO phase are quantitatively evaluated. • A accurate composition-structure-corrosion behavior prediction model is developed. • The corrosion mechanism in Mg-RE-Ni alloy is quantitatively revealed by machine learning. [ABSTRACT FROM AUTHOR]

• Six groups of fcc NiCrFe/LEA(MEA, HEA) diffusion couples were prepared. • Their composition profiles were experimentally measured by EPMA technique. • Interdiffusivities and tracer diffusivities in fcc NiCoCrFe system were evaluated. • Interdiffusivities of Co, Cr and Fe in MEAs and HEAs are lower than those in LEAs. • Sluggish diffusion in Co-Cr-Fe-Cr HEAs is not exist on absolute temperature scale. Six groups of fcc solid/solid diffusion couples, including Ni-Cr-Fe/ low-entropy (pure Ni, and NiCo, NiCr, and NiCoCr) alloys, Ni-Cr-Fe/ medium-entropy (CoCrNi) alloys, and Ni-Cr-Fe/ high-entropy (CoCrFeNi) alloys, were prepared, and their composition profiles were experimentally measured. Concentration-dependent interdiffusion and tracer diffusion coefficients in fcc Ni-Co-Cr-Fe system at 1473 K were retrieved with the aid of High-throughput Determination of Interdiffusion Coefficients (HitDIC) software and their reliability was validated. In most cases, D ˜ C r C r N i > D ˜ F e F e N i > D ˜ C o C o N i . The comprehensive comparison between the interdiffusivities/tracer diffusivities in the NiCo, NiCr, NiCoCr low-entropy, CoCrNi medium-entropy, and CoCrFeNi high-entropy alloys and those reported data available in the literatures indicates that the interdiffusivities Co, Cr, and Fe in low-entropy alloys are the largest than those in the other two types of alloys. While the tracer diffusivity in Co-Cr-Fe-Ni HEAs may have no sluggish phenomenon when the absolute temperature is used. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of diffusion kinetics of the Ti–Fe–V system is crucial for elucidating the solidification process in high-strength titanium alloys. In this paper, ten sets of diffusion couples within bcc Ti–Fe–V alloys that underwent annealing at temperatures of 1273K, 1323K, and 1373K were prepared. Composition-distance curves were determined using the electron probe microstructure analysis technique. Atomic mobility parameters and interdiffusion coefficients were obtained using the numerical inverse method with the assistance of HitDIC software. It should be noted that the atomic mobility parameters for Ti–Fe and Ti–V were reoptimized using the most up-to-date thermodynamic descriptions. This approach enables the acquisition of comprehensive data regarding the temperature-composition relationship in diffusion. D ˜ F e F e T i exhibits a markedly greater value compared to D ˜ V V T i . Both D ˜ F e F e T i and D ˜ V V T i demonstrate an increase with the increase of temperature. Furthermore, the Arrhenius equation can be applied to solve for the variation in frequency factors and activation energies concerning temperature and composition. • Ten groups of concentration profiles in bcc Ti–Fe–V alloys were measured. • The atomic mobility parameters for Ti–Fe and Ti–V were reoptimized using the most up-to-date thermodynamic descriptions. • Atomic mobility parameters in bcc Ti–Fe–V ststem were established directly from concentration profiles. • Interdiffusivities in bcc Ti–Fe–V alloys were obtained using the numerical inverse method. • D ˜ F e F e T i < ! − − Q 3 : Highlights should only consist of 125 characters per bullet point , including spaces. The highlights provided are too long ; please edit them to meet the requirement. − − > exhibits a markedly greater value compared to D ˜ V V T i , both D ˜ F e F e T i and D ˜ V V T i demonstrate an increase with rising temperature. [ABSTRACT FROM AUTHOR]

In this paper, a series of terminal alloys were first prepared, undergoing microstructure and composition characterizations through a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) techniques. Subsequent diffusion couple experiments were conducted to acquire initial concentration profiles in fcc Co-Mn-Fe and Co-Mn-Ni alloys. By leveraging experimental composition profiles from 12 groups of diffusion couples measured using EPMA, alongside the reported thermodynamic data, atomic mobility parameters within the fcc phase of the two ternary systems were accurately determined using HitDIC software. Employing the resulting kinetic databases, a comprehensive set of simulated data, including composition profiles and diffusion paths, was generated for all diffusion couples, demonstrating strong alignment with corresponding experimental results. Moreover, interdiffusivities spanning a wider composition range within the fcc phase of Co-Mn-Fe and Co-Mn-Ni systems were computed at different temperatures, shedding light on the diffusion behavior of alloy components in response to temperature and concentration fluctuations. Finally, drawing from the reported thermodynamic data and the currently matched atomic mobility parameters, overviews of the intricate relationships among diffusion-related properties and configurational entropy indicate that the endeavor to develop comprehensive thermodynamic and kinetic databases is essential for tailoring High-Entropy Alloys. • 12 groups of fcc single-phase Co-Mn-X (X = Fe, Ni) diffusion couples were prepared. • Self-consistent kinetic descriptions for target alloys were accurately determined. • High-throughput determination is achieved using the numerical inverse method. • Accuracy of the evaluated kinetic descriptions was comprehensively proved. [ABSTRACT FROM AUTHOR]

A new composition-design strategy was used to guide the development of Co-free eutectic high-entropy alloy. In the present work, we successfully realized the prediction of the eutectic point of CrFeNiNb x through the energy-dispersive spectrometer data of CoCrFeNiNb x. After that, we systematically investigated the effect of the Nb content on the phase-structure evolution and macro-mechanical properties of the equiatomic CrFeNi alloy. Experimental results show that the removal of Co reduces the eutectic point and decreases the solubility of the Nb element in the face-centered-cubic (FCC) phase. Compared with the Co-bearing eutectic, there are not obvious change of the morphology of the Co-free eutectic, while the interlaminar spacing and volume of the FCC phase increased, which resulting in a decrease in yield strength but a certain degree of improvement in compressive strain. [ABSTRACT FROM AUTHOR]

Valence electron concentration (VEC) was treated as a useful parameter to predict solid solution phases, and the VEC rule was proposed for high entropy alloys (HEAs). However, this empirical rule has its limitations, which restricts its applications for phase predictions in HEAs. In this paper, we revisited the empirical VEC rule with the HT-CALPHAD approach in the Al–Co–Cr–Fe–Ni system. Our investigation showed that more than 90% compositions are observed to have BCC structures when 5.7≤VEC≤7.2 and we got 100% FCC structures when VEC≥8.4. Meanwhile, we proposed a data screening procedure to classify and discover the new HEAs. The concepts of average density (ρ HEA), highest BCC/FCC temperatures (T B C C / F C C m a x), and temperature ranges (Δ T BCC / FCC) were introduced as useful data screening criteria to down-screen the candidate alloy compositions for specific engineering applications. In the current work, we have identified three HEA categories (refractory BCC HEAs, light-weight BCC HEA and refractory FCC HEAs) in the Al–Co–Cr–Fe–Ni system and proposed the best candidate in each group. More importantly, our investigation showed the HEA non-equiatomic composition space provides ample opportunities for the discovery of the next-generation HEAs. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this paper, 10 groups of ternary Ag–Sn–Zn diffusion couples were prepared under 873, 973 and 1073 K within the fcc single-phase region. The element distribution across the diffusional interface was measured by EPMA, and a high-throughput determination of atomic mobilities in Ag-rich fcc Ag–Sn–Zn alloys was performed by using HitDIC (High-Throughput Determination of Interdiffusion Coefficients, https://hitdic.com/) software in the framework of the numerical inverse method. A self-consistent set of atomic mobility parameters was obtained. Reliability of the evaluated atomic mobility parameters were further verified by reasonably reproducing the experimental composition profiles. Insight into the composition- and temperature-dependence of various diffusion properties in fcc Ag–Sn–Zn alloy were subsequently retrieved and discussed. Furthermore, through the related Arrhenius information, the diffusion frequency factors and diffusion activity energies within the corresponding temperature and the composition range were obtained. • Ten groups of fcc single-phase Ag–Sn–Zn diffusion couples were prepared. • Composition-dependent interdiffusivities in fcc Ag–Sn–Zn alloys were obtained. • With a numerical inverse method, the high-throughput determination was realized. • The reliability of the obtained interdiffusivities was comprehensively validated. [ABSTRACT FROM AUTHOR]

Reliable diffusivities and atomic mobilities of fcc Co–Mn–Cr alloys are the important keystones for establishing the accurate diffusion database for CoCrFeMnNi high-entropy alloys and other relevant alloys, but they are still missing in the literature. In this paper, diffusion couple experiments together with Hi gh- t hroughput D etermination of I nterdiffusion C oefficients (HitDIC) software were employed to efficiently obtain diffusion descriptions of fcc Co–Mn–Cr alloys. Six diffusion couples were prepared and examined to provide the prerequisite composition profiles. Feature selection and regularization techniques in HitDIC software were adopted to extract the corresponding interdiffusion coefficients and atomic mobilities. A reliable set of diffusion descriptions of the fcc Co–Mn–Cr alloys were therefore obtained and verified. Investigations of the underlying composition- and temperature-dependent diffusion behaviors were enabled and demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, 6 Cu-Al-Sn ternary and 8 Cu-Ni-Al-Sn quaternary solid diffusion couples within single fcc phase from 1023 K to 1173 K were fabricated. Employing the measured concentration profiles and interdiffusion fluxes, the atomic mobility parameters and interdiffusion coefficients in Cu-Al-Sn and Cu-Ni-Al-Sn systems were high-throughput evaluated using the numerical inverse method. The simulated composition distributions and interdiffusion fluxes in all the diffusion couples are consistent with the measured ones confirming the reliability of the atomic mobilities. The Matano-Kirkaldy method was also used to validate the reliability of the accuracy of the determined interdiffusion matrices. The 3D diagrams of main interdiffusivities in the Cu-Al-Sn and Cu-Ni-Al-Sn systems in the investigated ranges of composition and temperature were established to analyze the effects of components on the diffusivities. In the Cu-Al-Sn system, there is an increase in D ˜ A l A l C u with an increase in x Al , while D ˜ S n S n C u increases with increasing x Sn but decreases with the addition of Al. Additionally, the introduction of Ni results in a decrease in all the main interdiffusivities ( D ˜ N i N i C u , D ˜ A l A l C u and D ˜ S n S n C u ) in the Cu-Ni-Al-Sn system. [ABSTRACT FROM AUTHOR]

Owning the excellent high temperature properties, low cost and density, Al-Co-Cr-Fe-Ni-Ti high-entropy superalloys (HESAs) represent a potential substitute for Ni-based superalloys. In this paper, the composition-dependent interdiffusivity matrices of face centered cubic (fcc) Al-Co-Cr-Fe-Ni-Ti HESAs at 1473 K were first determined via a combination of diffusion multiple technique and HitDIC software based on the numerical inverse method. The correlations between the main interdiffusivities and the components suggest that alloying elements play great impact on diffusion in HESAs. After that, comprehensive comparisons of the interdiffusivities and tracer diffusivities in present fcc HESAs with the literature data in fcc-based pure elements, lower-order alloys and traditional high-entropy alloys were conducted. The results indicate that the sluggish diffusion effect exists for only some of the components in the present HESAs. Moreover, comparisons of the diffusion coefficients between the HESAs and traditional Ni-based superalloys with refractory elements show that the interdiffusivities in the present HESAs are lower than the Ni-based superalloys with most refractory elements, but higher than those with Ir, Re and Os. Furthermore, it is also found that refractory elements need to be added in order to further improve the creep resistance of the HESAs. • Interdiffusivity matrices of Al-Co-Cr-Fe-Ni-Ti HESAs at 1473 K were determined. • Correlations between main interdiffusivities and components were investigated. • Sluggish diffusion does not exist for all the elements in the present HESAs. • Refractory elements need to be added to improve the creep resistance of HESAs. [ABSTRACT FROM AUTHOR]