Machine Learning Enabled Prediction of Stacking Fault Energies in Concentrated Alloys

Gaurav Arora,Dilpuneet S Aidhy

doi:10.3390/met10081072

Abstract

Recent works have revealed a unique combination of high strength and high ductility in certain compositions of high-entropy alloys (HEAs), which is attributed to the low stacking fault energy (SFE). While atomistic calculations have been successful in predicting the SFE of pure metals, large variations up to 200 mJ/m2 have been observed in HEAs. One of the leading causes of such variations is the limited number of atoms that can be modeled in atomistic calculations; as a result, due to random distribution of elements in HEAs, various nearest neighbor environments may not be adequately captured in small supercells resulting in different SFE values. Such variation further increases with the increase in the number of elements in a given composition. In this work, we use machine learning to overcome the limitation of smaller system sizes and provide a methodology to significantly reduce the variation and uncertainty in predicting SFEs. We show that the SFE can be accurately predicted across the composition ranges in binary alloys. This capability then enables us to predict the SFE of multi-elemental alloys by training the model using only binary alloys. Consequently, SFEs of complex alloys can be predicted using a binary alloys database, and the need to perform calculations for every new composition can be circumvented.

Highlights

High-entropy alloys (HEAs) have recently attracted wide attention as future structural alloys [1,2,3,4,5,6,7,8].These alloys have exhibited superior hardness, yield strengths, and fracture toughness compared to conventional alloys [2,3,4,5,6,7,8]
These mechanism changes have been directly correlated to the stacking fault energy (SFE) of alloys, where it is observed that lowering the SFE favors the sequential change in the deformation mechanisms [9,13,14,15,16,17,18,19]
We find that the SFE variation decreases and the number of structures falling within a small distribution of SFE increases as the supercell size increases from 48 to 6000 atoms

Summary

Introduction

High-entropy alloys (HEAs) have recently attracted wide attention as future structural alloys [1,2,3,4,5,6,7,8].These alloys have exhibited superior hardness, yield strengths, and fracture toughness compared to conventional alloys [2,3,4,5,6,7,8]. A key distinguishing feature of HEAs from conventional alloys is the presence of multiple principal elements randomly distributed in large proportions on a given crystal lattice. This feature has opened up an exponentially large number of possible alloy compositions that have the potential to unveil many interesting properties. Recent experiments have shown that the underlying cause of the unique combination is the change in the deformation mechanisms from slip to twinning to transformation-induced plasticity [9,10,11,12,13,14] These mechanism changes have been directly correlated to the stacking fault energy (SFE) of alloys, where it is observed that lowering the SFE favors the sequential change in the deformation mechanisms [9,13,14,15,16,17,18,19]

Methods

Results

Discussion

Conclusion