Abstract
We report a hydrogen induced vacancy formation mechanism in tungsten based on classical molecular dynamics simulations. We demonstrate the vacancy formation in tungsten due to the presence of hydrogen associated directly with a stable hexagonal self-interstitial cluster as well as a linear crowdion. The stability of different self-interstitial structures has been further studied and it is particularly shown that hydrogen plays a crucial role in determining the configuration of SIAs, in which the hexagonal cluster structure is preferred. Energetic analysis has been carried out to prove that the formation of SIA clusters facilitates the formation of vacancies. Such a mechanism contributes to the understanding of the early stage of the hydrogen blistering in tungsten under a fusion reactor environment.
Highlights
Defects such as vacancies, grain boundaries and dislocations have significant impact on both the structural and mechanical properties of metals
The hydrogen induced vacancy formation in tungsten, which is considered as the initial step of the hydrogen blistering, has been investigated via classical molecular dynamics simulations
It is shown that vacancies are created due to the presence of hydrogen in tungsten and the vacancy formation mechanism is closely related to the formation of certain self-interstitial structures
Summary
Grain boundaries and dislocations have significant impact on both the structural and mechanical properties of metals. Among these the vacancy has always drawn intense interest owing to its effects on properties such as diffusion, electrical resistivity and alloy hardening.. As one of the intrinsic point defects in metals, the vacancy usually has a quite low concentration of the order of 10−4 below the melting point under thermal equilibrium conditions.. External conditions like rapid quenching or high energy particle irradiation can induce vacancy formation in metals, which are usually applied as important ways to investigate the effects of vacancies. Hydrogen retention experiments have been carried out to examine the blistering problem. The hydrogen retention reaches a maximum around an exposure temperature of 500 K at which
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