Adhesion of voids to bimetal interfaces with non-uniform energies.

Shijian Zheng,Jian Zhang,Michael J Demkowicz,Yongqiang Wang,Irene J Beyerlein,Nathan A Mara,Shuai Shao

doi:10.1038/srep15428

Abstract

Interface engineering has become an important strategy for designing radiation-resistant materials. Critical to its success is fundamental understanding of the interactions between interfaces and radiation-induced defects, such as voids. Using transmission electron microscopy, here we report an interesting phenomenon in their interaction, wherein voids adhere to only one side of the bimetal interfaces rather than overlapping them. We show that this asymmetrical void-interface interaction is a consequence of differing surface energies of the two metals and non-uniformity in their interface formation energy. Specifically, voids grow within the phase of lower surface energy and wet only the high-interface energy regions. Furthermore, because this outcome cannot be accounted for by wetting of interfaces with uniform internal energy, our report provides experimental evidence that bimetal interfaces contain non-uniform internal energy distributions. This work also indicates that to design irradiation-resistant materials, we can avoid void-interface overlap via tuning the configurations of interfaces.

Highlights

Are distributed asymmetrically, lying on the side of the phase with the lower surface energy, which is the Ag side at the Ag-Cu interfaces
Voids were induced via He irradiation on transmission electron microscopy (TEM) foils of the Cu-Ag nanolayered composite
Previous simulations have found that similar wetting arguments to those given above may be used to explain the formation of He precipitates at Cu-Nb interfaces with a Kurdjumov-Sachs orientation relationship (KS Cu-Nb)[16]

Summary

Introduction

Are distributed asymmetrically, lying on the side of the phase with the lower surface energy, which is the Ag side at the Ag-Cu interfaces. This finding is consistent with predictions of non-uniform internal interface energy, which allows voids to wet some parts of the interface from one side of the interface, but not other parts. Surface wetting of interfaces with uniform energies.

Results

Conclusion