Mechanism of vacancy formation induced by hydrogen in tungsten

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.

Study of hydrogen isotopes behavior in tungsten by a multi trapping macroscopic rate equation model

“…Indeed, it has been already demonstrated by [17] and classical Molecular Dynamics [18] that HIs The resulting simulated TDS spectrum presented in fig. 1 (b) shows 2 desorption peaks at 420 K and 630 K which correspond well with the experimental measurement.…”

Growth mechanism of subsurface hydrogen cavities in tungsten exposed to low-energy high-flux hydrogen plasma

“…For H plasma exposure, blister means the dome-shape structure observable on the surface, usually associated with an underlying subsurface cavity that could be confirmed by SEM views of the cross section prepared by focused ion beam (FIB) [2,8,9]. The surface blistering of W is generally linked to the cavity formation as a result of plastic deformation [3,6,10], dislocation loop punching [6,11], agglomeration of H-vacancy complexes [12], and solute H isotope distribution [13]. Among them, plastic deformation and dislocation loop punching are widely regarded as the most common and trustworthy growth mechanisms of the sub-surface cavities (i.e.…”

Effect of hydrogen on grain boundary migration in tungsten

“…We also noticed that the formation of the first SIA is closely associated with the H atoms implying that the formation of the first SIA results from the synergistic effect of multiple H atoms. A similar extrusion mechanism of vacancies in W induced by the H atoms is also discussed in the previous work [16], which shows a synergistic effect of H atoms in the coupling formation of vacancies and SIAs. And in certain case with enough SIAs, the SIAs should form energetically favorable ordered clusters.…”

“…Besides the SIAs and the vacancies, H will also be retained in W in fusion reactor environment. The behaviors of H in W as well as other structural materials have been widely investigated with various computational approaches [16][17][18][19][20][21][22][23][24][25][26][27] and experimental techniques [7,[28][29][30][31][32][33][34][35][36]. The defects in W, such as vacancies [20,37], dislocations [38] and GBs [18,19], have been shown to be responsible for the H bubble formation, which have systemically been reviewed from modeling and simulation point of view [24].…”