Effect of interstitial hydrogen on elastic behavior of metals: An ab-initio study

A comprehensive assessment of interstitial hydrogen on the elastic behavior across different metals (Al, Ni, Fe, Nb, Ti, and Zr) was carried out using first-principles calculations. The volumetric strain introduced by interstitial hydrogen had a key role in the observed variation in elastic constants. However, in Nb, Ti, and Zr, the host and hydrogen atoms interact strongly which had a significant contribution towards the variation in elastic response due to the presence of hydrogen. The addition of hydrogen reduced the resistance to shear deformation along respective active slip systems for all the metals, except Nb. Similarly, the homogenized macroscopic approximation of Young's and shear moduli also demonstrated a drop with increasing hydrogen concentration across all the metals, apart from Nb. Finally, these findings accurately quantify the variation in elastic behavior of various metals when exposed to a hydrogen rich environment.