Gradient Confinement Induced Uniform Tensile Ductility in Metallic Glass

X L Lu,Y Li,Q H Lu,L Lu

doi:10.1038/srep03319

X L Lu, Y Li + Show 2 more

Open Access

https://doi.org/10.1038/srep03319

Copy DOI

Abstract

Metallic glass (MG) generally fails in a brittle manner under uniaxial tension loading at room temperature. The lack of plastic strain of MG is due to the severe plastic instability via the easily formed one dominate shear band. There have been several approaches to improve the ductility in MG, but achieving uniform tensile ductility for monolithic MG in bulk size remains a challenge. Here we demonstrate a uniform tensile ductility of 12% achieved in a micrometer scale Ni-P amorphous film coated on a Ni substrate with gradient structure. Instead of a single run-away shear band, such a gradient structure generates massive extensive multiple shear bands in the film, leading to a record high tensile ductility in MG. The present finding highlights a novel route for achieving uniform tensile ductility in monolithic metallic glass with bulk size.

Highlights

Metallic glass (MG) generally fails in a brittle manner under uniaxial tension loading at room temperature
There have been several approaches to improve the ductility in MG, but achieving uniform tensile ductility for monolithic MG in bulk size remains a challenge
The amorphicity of the Ni-P film is further confirmed by the transmission electron microscope (TEM) diffraction and X-ray (Supplementary Information Fig. S2)

Summary

Introduction

Metallic glass (MG) generally fails in a brittle manner under uniaxial tension loading at room temperature. Experiments had demonstrated that efficient confinement of plastic deformation by the substrate can suppress the strain localization and delay the catastrophic failure, leading to a considerable tensile elongation in the NC metals. This understanding enlightens the possibility to achieve tensile elongation in metallic glass as long as strain localization in the specimen can be constrained, for example, through the GNG substrate. Subsequent tensile tests revealed a 12% uniform tensile ductility on macro-sized amorphous films achieved through the generation of high density of shear bands in a tensile specimen has not been reported before

Methods

Results

Conclusion