Correlation between structural heterogeneity and plastic deformation for phase separating FeCu metallic glasses.

Chuan-Xiao Peng,Simon Pauly,Li Wang,Kai-Kai Song,Daniel Şopu,Jürgen Eckert

doi:10.1038/srep34340

Abstract

Unlike crystalline metals, the plastic deformation of metallic glasses (MGs) involves a competition between disordering and structural relaxation ordering, which is not well understood, yet. Molecular dynamics (MD) simulations were performed to investigate the evolutions of strain localizations, short-range order (SRO) as well as the free volume in the glass during compressive deformation of Fe50Cu50 MGs with different degrees of phase separation. Our findings indicate that the free volume in the phase separating MGs decreases while the shear strain localizations increase with increasing degree of phase separation. Cu-centered clusters show higher potential energies and Voronoi volumes, and bear larger local shear strains. On the other hand, Fe-centered pentagon-rich clusters in Cu-rich regions seem to play an important role to resist the shear transformation. The dilatation or annihilation of Voronoi volumes is due to the competition between ordering via structural relaxation and shear stress-induced deformation. The present study could provide a better understanding of the relationship between the structural inhomogeneity and the deformation of MGs.

Highlights

Unlike crystalline metals, the plastic deformation of metallic glasses (MGs) involves a competition between disordering and structural relaxation ordering, which is not well understood, yet
It seems that the more phase separated samples have a lower elastic limit and are softer due to the more pronounced phase separation introduces some more “soft spots” and more “fertile zones” for shear transformations
Previous reports have demonstrated that the sharp drop of the stresses after yielding can be related to a single shear banding process[18], which in turn implies that the samples in our case could show multiple shear location states during deformation

Summary

Introduction

The plastic deformation of metallic glasses (MGs) involves a competition between disordering and structural relaxation ordering, which is not well understood, yet. Molecular dynamics (MD) simulations were performed to investigate the evolutions of strain localizations, shortrange order (SRO) as well as the free volume in the glass during compressive deformation of Fe50Cu50 MGs with different degrees of phase separation. The plastic deformation of MGs is localized within shear bands, being different from their crystalline counterparts, which causes brittleness and catastrophic failure during deformation[4,5] This severely hampers the practical applications of MGs as structural materials. We present a MD study on the compressive deformation of phase separating Fe50Cu50 MGs at a temperature of 100 K in an attempt to clarify the structural evolutions relating to shear strain localizations at an atomic level

Methods

Results

Conclusion