An interplay between a hydrogen atmosphere and dislocation characteristics in BCC Fe from time-averaged molecular dynamics

Abstract

The interplay between hydrogen and dislocations (e.g., core and elastic energies, dislocation-dislocation interactions) has implications on hydrogen embrittlement but is poorly understood. Continuum models of hydrogen enhanced local plasticity have...

Hydrogen isotope population near dislocations in zirconium from molecular dynamics

“…To overcome this challenge, time-averaged MD simulations are utilized. Contrary to intuition, time-averaged MD with a sufficiently long average time produces more converged results than energy minimization [ [31] , [32] , [33] ]. To prevent the hydrogen isotope atom from moving out of the region of the insertion site, a reflect box measuring 10 × 10 Å 2 in the x × y plane, spanning the entire z dimension, is utilized, as shown in Fig.…”

Atomistic Study of the Interaction Nature of H-Dislocation and the Validity of Elasticity in Bcc Iron

“…From the point of view of energy, H prefers to occupy an octahedral site rather than a tetrahedral site to lower the total energy of the system, since at an octahedral site H induces ~0.2 shear strain (ε xy ), eight times that induced at a tetrahedral site. A large number of hydrogen atoms can be trapped in the slip plane forming a wide area of H atmosphere around the dislocation, which exerts a strong drag effect for slipping dislocations [14,41].…”

“…More details of the interactions, including H binding sites [10], distribution of binding energies [12], and H migration path [10][11][12][13] have been discussed carefully. However, atomistic studies are mostly focused on the simple cases where H is interacting with only one or two dislocations, or H is binding around a slow dislocation [14][15][16]. When the interactions occur between H atoms and multiple dislocations and cost a lot of time (e.g., H diffusion to dislocations), atomistic simulations are not so applicable.…”

“…Later, the dislocation stress field calculated using anisotropic elasticity was applied to describe solute-dislocation interaction [22]. Up to now, elasticity has been widely applied to investigate the solute atmosphere around dislocation, dislocation motion with solutes, solute-dislocation junction interaction, and solute strengthening of dislocation [14,[23][24][25]. Despite its wide success, the reliability and accuracy of elastic theory remains to be examined.…”

Hydrogen on screw dislocation in Fe and W: Existence of 3D-compound and exotic segregation profile

“…Hydrogen segregation has often been studied at vacancy [14], surfaces [15,16], grain boundaries [2,14,[17][18][19][20][21][22][23], and dislocations [24][25][26][27][28][29][30]. For dislocations, hydrogen segregation was modeled either using elastic theory [31,32], Molecular Statics or Monte-Carlo (MC) simulations with semi-empirical potentials [31,[33][34][35], or using ab initio calculations to obtain energetic interactions used as input data in rigid-lattice MC simulations or mean-field (MF) models [25,29,30,36,37].…”