Hydrogen Segregation in Palladium and the Combined Effects of Temperature and Defects on Mechanical Properties

TL;DR

This study uses atomistic simulations to explore how hydrogen, temperature, and structural defects affect the mechanical strength of palladium, revealing that these factors collectively promote material degradation and hydrogen trapping at grain boundaries.

Contribution

It provides new insights into the combined effects of defects, hydrogen, and temperature on palladium's mechanical properties through atomistic modeling.

Findings

Hydrogen localizes at grain boundaries at room temperature.

Defects and hydrogen synergistically weaken mechanical strength.

Hydrogen trapping is enhanced by vacancies and grain boundaries.

Abstract

Atomistic calculations were carried out to investigate the mechanical properties of Pd crystals as a combined function of structural defects, hydrogen concentration and high temperature. These factors are found to individually induce degradation in the mechanical strength of Pd in a monotonous manner. In addition, defects such as vacancies and grain boundaries could provide a driving force for hydrogen segregation, thus enhance the tendency for their trapping. The simulations show that hydrogen maintains the highest localization at grain boundaries at ambient temperatures. This finding correlates well with the experimental observation that hydrogen embrittlement is more frequently observed around room temperature. The strength-limiting mechanism of mechanical failures induced by hydrogen is also discussed, which supports the hydrogen-enhanced localized plasticity theorem.