Microstructure and composition dependence of mechanical characteristics of nanoimprinted AlCoCrFeNi high-entropy alloys

Dinh-Quan Doan,Tao-Hsing Chen,Te-Hua Fang

doi:10.1038/s41598-021-93272-y

Dinh-Quan Doan, Tao-Hsing Chen + Show 1 more

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https://doi.org/10.1038/s41598-021-93272-y

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Abstract

Molecular dynamics is applied to explore the deformation mechanism and crystal structure development of the AlCoCrFeNi high-entropy alloys under nanoimprinting. The influences of crystal structure, alloy composition, grain size, and twin boundary distance on the mechanical properties are carefully analyzed. The imprinting load indicates that the highest loading force is in ascending order with polycrystalline, nano-twinned (NT) polycrystalline, and monocrystalline. The change in alloy composition suggests that the imprinting force increases as the Al content in the alloy increases. The reverse Hall–Petch relation found for the polycrystalline structure, while the Hall–Petch and reverse Hall–Petch relations are discovered in the NT-polycrystalline, which is due to the interactions between the dislocations and grain/twin boundaries (GBs/TBs). The deformation behavior shows that shear strain and local stress are concentrated not only around the punch but also on GBs and adjacent to GBs. The slide and twist of the GBs play a major in controlling the deformation mechanism of polycrystalline structure. The twin boundary migrations are detected during the nanoimprinting of the NT-polycrystalline. Furthermore, the elastic recovery of material is insensitive to changes in alloy composition and grain size, and the formability of the pattern is higher with a decrease in TB distance.

Highlights

Over the past decades, a variety of materials have been widely developed with the continuous efforts of scientists and engineers to expand their applications
We have analyzed the influence of the crystal structure and alloy composition on the mechanical properties of face-centered cubic (FCC) AlCoCrFeNi high-entropy alloys (HEAs) during the nanoimprinting through molecular dynamics (MD) simulations
The results of imprinting force, deformation distribution, structure evolution, dislocation density, atomic displacement, and elastic recovery ratio have clarified the properties of AlCoCrFeNi HEA

Summary

Introduction

A variety of materials have been widely developed with the continuous efforts of scientists and engineers to expand their applications. The formation of simple solid solution phase with multi principal elements in HEA is enhanced by highly mixed entropy coupled with the slow diffusion of the atoms[10,11]. These novel compositions provide expanded solid solution phases with single or matrix phase at the atomic level in the structures of face-centered cubic (FCC), body-centered cubic (BCC), and hexagonal close-packing (HCP), so the HEAs possess unique characteristics[12,13]. To further explore the mechanical characteristics of AlxCoCrFeNi HEAs, MD simulation is used to probe the deformation behavior and microstructure development under the nanoimprinting process in the present work. The grain and twin boundaries (GBs/TBs) play important roles in nanoimprinting

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Results

Conclusion