Study on Helium Bubble Coalescence in Titanium with Dislocations

Baoling Zhang,Chongyang Li,Xue Su,Junwei Zhang

doi:10.4236/wjnst.2021.112005

Abstract

Dislocation and grain boundary have great influence on helium behavior in materials. In this paper, the helium bubble coalescence in titanium with dislocations was simulated using molecular dynamics method. The results show that, when the second helium bubble nucleates near the slip plane, it grows toward the first helium bubble which lies at the dislocation core till they coalesce with each other. However, it is not easy for the coalescence to occur if the two helium bubbles lie in different atomic layers in (001) plane. If the second helium bubble is nucleated on the side of the slip plane with full atomic layers, the second helium bubble growth could lead to the movement of the first helium bubble toward the other sides of the slip plane. The growth rate and direction of the second helium bubble are closely related to the pressure around it.

Highlights

In fusion equipment Tokamak, the first wall has to withstand very harsh conditions
The results show that, when the second helium bubble nucleates near the slip plane, it grows toward the first helium bubble which lies at the dislocation core till they coalesce with each other
If the second helium bubble is nucleated on the side of the slip plane with full atomic layers, the second helium bubble growth could lead to the movement of the first helium bubble toward the other sides of the slip plane

Summary

Introduction

In fusion equipment Tokamak, the first wall has to withstand very harsh conditions. One of particular concerns is the serious radiation damage of materials induced by the helium particles escaping from the plasma or (n, α) reaction [1] [2]. It has already been proven that helium atoms prefer to migrate and gather forming helium bubbles which can seriously destroy the mechanical properties of materials, such as the material deformation, cracking, embrittlement, and so on. It is crucial to improve the ability of materials to resist helium irradiation damage in the development of nuclear fusion. Many experiments have been carried out in order to improve the helium resistance ability of materials [3] [4] [5].

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Results

Conclusion