Effects of Embedded Helium on the Microstructure and Mechanical Properties of Erbium Films.

Wenbo Fu,Xinggui Long,Huahai Shen,Xiaosong Zhou,Liqun Shi

doi:10.3390/nano9111564

Wenbo Fu, Xinggui Long + Show 3 more

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https://doi.org/10.3390/nano9111564

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Abstract

A series of helium (He) charged nanograin-sized erbium (Er) films were deposited by direct current (DC)-magnetron sputtering with different He/Ar mixture gases. The microstructure and mechanical properties of He-charged Er films were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nanoindentation. The helium concentrations in Er films, determined by elastic recoil detection analysis (ERDA), ranged from 0 to 49.6%, with the increase in He:Ar flow ratio up to 18:1. The XRD results show that the grain sizes of Er films decreased with and increase in He content. The embedded He atoms induced the formation of spherical nanometer He bubbles, and the diameter of the He bubbles increased with the He content. The hardness and Young’s modulus increased and decreased with the decreasing grain sizes of polycrystalline Er–He films. The mechanisms of mechanical properties with respect to the grain size and He content were discussed based on the Hall–Petch formula and composite spheres model.

Highlights

Erbium is a vital candidate material for tritium storage in solid phase [1], due to its higher thermal stability of its tritide and better accommodation ability for helium atoms generated by the decay of tritium [2]
Snow et al [2] systematically studied the mechanism of 3He bubble growth by transmission electron microscopy (TEM) with the aging of Er tritide up to the 3He content of 0.37
The effects of the embedded He atoms on the microstructures and mechanical properties of Er–He films were studied by X-ray diffraction (XRD), TEM, elastic recoil detection analysis (ERDA), and nanoindentation

Summary

Introduction

Erbium is a vital candidate material for tritium storage in solid phase [1], due to its higher thermal stability of its tritide and better accommodation ability for helium atoms generated by the decay of tritium [2]. The He bubble evolution-induced mechanical property degradation impedes its application in the field of nuclear industry. The Ti films with a He/Ti atomic ratio as high as 56 at.% were fabricated without artificial defects [18] In this way, the amount of embedded helium could be well regulated and controlled, as well as the free of irradiation damage in the metal matrix in the implantation processing. The effects of the embedded He atoms on the microstructures and mechanical properties of Er–He films were studied by X-ray diffraction (XRD), TEM, elastic recoil detection analysis (ERDA), and nanoindentation

Sample Preparation

Sample Characterizations

Results and Discussions