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Eutectic high entropy alloy with seven components is designed based on the integrated computational materials engineering (ICME) framework. The framework includes thermodynamic prediction using calculation of phase diagrams (CALPHAD), microstructure simulation using phase-field method, and experimental validation. The designed alloy shows the eutectic structure consisting of FCC and laves phase in the composition range from 8.25 to 10 at. pct Ta. The simulation and experimental results are co-related and a framework is proposed that can be used for high entropy alloy design subjected to various manufacturing processes. [ABSTRACT FROM AUTHOR]

Undercooling studies were carried out in equiatomic CuCoNi system with an aim to understand the growth kinetics and microstructural variations as a function of undercooling. The morphological change in microstructure was observed and correlated with the undercooling obtained. Non-linear variation of growth velocity with respect to the increase in undercooling was obtained from high-speed video measurements. The variation in growth velocity was compared with the dendritic growth model with a modified kinetic undercooling term. The segregation profile was predicted using multi-phase field method and compared with the experimental data. Micro-hardness variation was correlated with the undercooling obtained. [ABSTRACT FROM AUTHOR]

Multi-principle element alloy FeCoNiCu with varying Sn addition was undercooled using the meltfluxing technique to illustrate the dependence of growth kinetics on Sn addition. The alloy FeCoNiCuSn 0.5 shows morphological variation in the microstructure from dendritic to equiaxed grain morphology with the increase in undercooling. The alloy FeCoNiCuSn 5 shows dendrite morphology with undercooling. The dendritic growth velocity was sluggish with solute addition,i.e., at an undercooling of 200 K, the growth velocity decreased from ~25 m/s to 6 m/s while varying Sn concentration from 0.5 to 5 at % suggesting solute drag effect. The microhardness improvement could be correlated to the microstructure refinement achieved during undercooling. [ABSTRACT FROM AUTHOR]

High entropy alloys with multiple phases are taken for undercooling studies and established the microstructure evolution with respect to undercooling. The melt fluxing technique was used for the current study to achieve undercooling. Predictions on the equilibrium phase formation of these systems was performed using CALPHAD approach and compared with experimental observations. Metastable microstructures were observed during undercooling and the morphological changes could be correlated with the currently established mechanisms. The detailed microstructure evolution in FeCoNiCuX 0.5 (X = Al, Mo, Ti, W, Zr) shows the minute addition of these elements results in variation in microstructure evolution during as cast as well as undercooled condition. The studied systems show a maximum undercooling of more than 0.18 T L. and maintained crystalline nature even in deep undercooling. The segregation nature of elements was studied and correlated with the phase field simulations obtained. • First study to establish the morphological changes in high entropy alloy with respect to undercooling. • Prediction of segregation behaviour in undercooled and solidified FeCoNiCuX 0.5 alloy using phase field simulation. • Studied the effect of minute solute addition in undercooled high entropy alloy. [ABSTRACT FROM AUTHOR]

The non-equilibrium response of a high entropy alloy CoCuFeNiTa 0.5 has been studied using undercooling as a control parameter. The solidification growth rates are rapid (30–50 m/s) at deep undercooling (>150 °C) and are comparable with conventional alloys. The elemental segregation especially that of Cu as predicted by phase field simulations in lower (<50 °C) undercooling regime matches with the experimental observations. This study indicates that even extreme non-equilibrium conditions during solidification could not avoid elemental segregation at the atomic scale. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Designing high entropy alloys (HEAs) from a large compositional space is challenging. The design process is accelerated by integrating computational techniques. The current study developed a framework for the accelerated identification of phases in HEAs by integrating high throughput calculations and machine learning (ML). The 19968 composition information was generated using high throughput CALculation of PHAse Diagrams (CALPHAD) calculations and used as a dataset for the machine learning algorithms. The Synthetic Minority Over-sampling Technique (SMOTE) makes unbiased data, and multiple machine learning algorithms are trained and compared. The Support Vector Machine (SVM) and Artificial Neural Network (NN) show test accuracy of ∼99%. The trained algorithm was used to predict phases in ternary, quaternary and quinary systems. The experimental comparison confirms that the algorithms successfully predicted the phase transitions in HEAs with respect to varying compositions. The developed framework can be adopted for designing new materials. • An integrated framework for the prediction of phases in multicomponent alloys using machine learning (ML). • A large data set was generated through high throughput studies and SMOTE technique was used to avoid biasing in the data. • Several ML algorithms are trained and identified the accuracy of each of them for phase prediction for the current dataset. [ABSTRACT FROM AUTHOR]

Hot deformation behaviour of AlCoCrFeNi 2.1 eutectic high entropy alloy, consisting of fcc (CoCrFe-rich) and BCC (NiAl-rich) phases is studied by generating contour maps of multiple models using high temperature thermo-mechanical simulator compression test data. The workability regimes for thermomechanical processing are identified as 1073–1150 K and 10 −3 – 10 −2.2 s −1 as well as 1338–1373 K and 10 −3 –10 −1.2 s −1 . Finite element simulation has been used to study the strain distribution and material flow during hot deformation, which assists for predicting actual material flow in forging process. Flow instabilities during hot forming has been avoided by adopting integrated approach. [ABSTRACT FROM AUTHOR]

The additive manufacturing (AM) of eutectic high-entropy alloys (EHEAs) with seven components was simulated. The as-cast alloy comprised of primary dendritic phase and eutectic region between the FCC and Laves phase. The additive thermal cycle generated by the analytical model was used for phase-field and physical simulations. A thermomechanical simulator was used to perform the physical simulation. Scanning electron microscopy (SEM) was used to characterize the effect of AM on the thermal cycle of the test samples and the results showed that the sigma phase was formed in the primary dendritic phase. The formation of the sigma phase was correlated with thermodynamic predictions and heat treatment studies. The thermal cycle of the microstructure, which was predicted using the phase-field simulation, was correlated with the experimental results. The integrated approach that was adopted in the current study can be utilized for the accelerated exploration of alloys for additive manufacturing. • Integrated study of physical and computer simulation to identify the effect of additive manufacturing conditions in materials. • New phase formation during the additive condition for seven component EHEA. • Framework for accelerated screening new alloys for AM. [ABSTRACT FROM AUTHOR]

• Design and development of Co 25 Cr 20 Fe 25 Ni 25 V 5 FCC high entropy alloy (HEA) using ICME approach. • Understanding the segregation behavior of FCC HEA using phase field simulation. • Formation of the deformation bands in the lower temperature range 1073–1173 K causes hardening. • Observation of annealing twin in FCC HEA during deformation in the high temperature range 1273–1373 K. [Display omitted] In the present study, using ICME approach, the development of Co-Cr-Fe-Ni-V based single-phase FCC high entropy alloy (HEA) has been explored. The simulation guided composition was arc melted and verified using microstructure characterization. The as-cast sample was subjected to deformation at a strain rate of 0.1 s−1in the temperature range of 1073–1373 K. The flow stress behavior in this temperature range could be correlated with the evolution of microstructure using EBSD. Based on these results, the deformation behavior of the alloy at elevated temperature is rationalized. The current study realizes the ICME approach to develop novel single-phase FCC HEA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Application and comparison of multiple machine learning algorithms for the design of HEAs with solid solution phases. • ANN and Random Forest algorithm shows better accuracy for the current data set. • VEC and T m parameters have more importance for the phase prediction based on the current data set. • ANN can predict new BCC + FCC multiphase medium entropy alloy based on the current data set. • The best accuracy of more than ~ 80% obtained with multiple classification algorithms. Identification of compositions that form solid solution phases from a large compositional space is challenging. The current study focuses on applying multiple machine learning classification algorithms for suitably predicting new medium to high entropy alloys with solid solution phases. The current data set used for training and testing consisting of 664 labeled data with 267 BCC alloys, 199 FCC alloys, and 198 (FCC + BCC) alloys to avoid biased predicting. The analyzed data shows a strong correlation between the empirical design parameters. The correlation coefficient values changed while moving the alloy system from medium to high entropy domain. The parameters VEC and T m show high importance in prediction compared to other parameters. The importance of design parameters is analyzed, and the accuracy is quantified. The experimental results validate the prediction of a shift from BCC + FCC to FCC phases while increasing Ni content in the CoCuFeNi x system. [ABSTRACT FROM AUTHOR]

Multicomponent Co 25 Fe 25 Mn 5 Ni 25 Ti 20 eutectic high entropy alloy (EHEA), synthesized by vacuum arc melting followed by suction casting method resulted in two types of solid solution phases (fcc CoFeNi-rich (α) and bcc Ti-rich (β)) and Ti 2 (Ni, Co) type Laves phase. The hot deformation behaviours have been investigated at a temperature ranging from 1073 to 1273 K and different strain rates (10−3,10−2,10−1and 1 s−1). The optimum hot workability conditions of EHEA lies in temperature range 1073–1273 K and strain rate range 10−3 s−1-10−1.6 s−1 as well as temperature 1130–1225K and strain rate 10−0.5-1 s−1. The constitutive relation is established to understand the plastic deformability at high temperature. Finite element simulation has also been used to predict the deformation behaviour during the hot working process. • Co 25 Fe 25 Mn 5 Ni 25 Ti 20 EHEA exhibits eutectic between fcc solid solution phase (α) and Ti 2 (Ni, Co) type Laves phase. • Constitutive relation is established using calculated activation energy (∼311 kJ/mol) and stress exponent value (n = 3.5). • Hot workability regimes are identified by generating contour plots using multiple model parameters. • Effective plastic strain field distribution at different temperatures are understood using FEM simulation. [ABSTRACT FROM AUTHOR]