A quantification study of hydrogen-induced cohesion reduction at the atomic scale

Abstract

Although hydrogen embrittlement has been observed and in detail studied nearly for one and a half-century in the past, the physically-based quantitative mechanism is not available yet. Here a new quantification mechanism of H embrittlement at atomic scale applicable for various metals is demonstrated. The process of the cohesion reduction caused by the lattice trapping H atoms in interstices is physically expressed. Specifically, the strongly intensified Pauli repulsion in interstices occupied by H atoms caused by the local increase of electron density leads to lattices dilatate and thus metallic cohesion diminish. The ab initio simulation is conducted to validate the quantification mechanism and the theoretical results of the nearest neighbor atom distance and the maximum cohesion strength agree pretty well with the simulation results for various metals trapping H atoms. The study reveals the content and location of the trapped H atoms and the electronic structure properties of host metals co-determine the cohesion strength of the lattice after trapping H atoms, provides the atomic scale mechanism to quantify the general cohesion reduction of the lattice trapping H atoms, and takes the essential step in predicting the evolution of metallic material mechanical properties in the environment contained H atoms.

Keywords

• Hydrogen embrittlement
• Lattice dilatation
• Pauli repulsion
• Quantification mechanism
• Ab initio simulation