Predictive model of hydrogen trapping and bubbling in nanovoids in bcc metals

Abstract

Interplay between hydrogen and nanovoids, despite long-recognized as a central aspect in hydrogen-induced damages in structural materials, remains poorly understood. Focusing on tungsten as a model BCC system, the present study, for the first time, explicitly demonstrated sequential adsorption of hydrogen adatoms on Wigner-Seitz squares of nanovoids with distinct energy levels. Interaction between hydrogen adatoms on the nanovoid surface is shown to be dominated by pairwise power law repulsion. A predictive model was established for quantitative prediction of configurations and energetics of hydrogen adatoms in nanovoids. This model, further combined with equation of states of hydrogen gas, enables prediction of hydrogen molecule formation in nanovoids. Multiscale simulations based on the predictive model were performed, showing excellent agreement with experiments. This work clarifies fundamental physics and provides full-scale predictive model for hydrogen trapping and bubbling in nanovoids, offering long-sought mechanistic insights crucial for understanding hydrogen-induced damages in structural materials.Being the most abundant element in the known universe and a typical product from corrosion, hydrogen (H) exists virtually in all service environments. The exposure of metallic materials to H-rich environments can result in numerous structural damages, including H induced cracking 1, 2 , H induced surface blistering/flaking 3-7 , and H induced porosity/swelling 8-13 , among others. These damages undesirably degrade the structural and mechanical integrity of materials 14-16 , often causing premature and even catastrophic failures 4, 6, 17 , and thus jeopardizing safety and efficiency of many applications. It's generally believed that these damages originate from interactions between H and various lattice defects. One key issue among those interactions is the H interplay with nanovoids, which promotes the formation and growth of mesoscale H bubbles and consequently leads to experimentally observable failures in structural materials 3-11, 15, 16, 18 .

Interpreting nanovoids in atom probe tomography data for accurate local compositional measurements

“…anosized voids, including pores, cavities, and bubbles, are common defects found in materials 1 . Voids can be generated under a variety of service conditions and are most often detrimental to the material's structural properties.…”

A brief review of data-driven ICME for intelligently discovering advanced structural metal materials: Insight into atomic and electronic building blocks

“…The microstates/configurations/local orders are essential to reveal their structure-property relationship [49,50,51,52]. Predictive models have been proposed to reveal the hydrogen trapping and bubbling in nanovoids in bodycentered-cubic (BCC) metals, which integrate the multiscale calculations including DFT calculations, classical MD simulations, and kinetic Monte Carlo simulations [53]. The microstates/clusters dominated shear bands or serrations of high-entropy alloys and metallic glasses during deformation are reported [51,54].…”

“…10(c). Therefore, with electronic and atomic structures, the mechanisms and models of hydrogen-induced damage in structural metal materials can be revealed clearly [53,61,142,143,144]. Recently, first-principles modeling of anisotropic anodic dissolution of metals and alloys in corrosive environments reveals a formula to specify the relationship between the electrode potential and the current density by considering the basic parameters of surface energy density and work function, providing a promising perspective for designing better corrosion-resistant alloys [144].…”

The effect of a pre-existing nanovoid on martensite formation and interface propagation: a phase field study

“…The coupled system of CH (Equation (7)) and elasticity equations (Equation (10)) can be solved to obtain the evolution of the nanovoid concentration and, consequently, the nanovoid morphology. The growth and propagation of a nanovoid can be suppressed due to various reasons, such as change in temperature, external mechanical loading and internal stresses, caused by other defects [99–102] due to which the nanovoid is finally stopped with a certain shape and a certain size. Since we are interested in studying the interaction of a pre-existing nanovoid with the A – M transformation, a circular nanovoid with a desirable size is here generated by manually stopping the coupled CH–elasticity solution contingent upon the creation of a complete nanovoid surface with the concentration varying from c = 0 to c = 1 .…”