Effects of Cr, Mn, and Fe on the hydrogen solubility of Ni in high-pressure hydrogen environments and their electronic origins: An experimental and first-principles study

Abstract

Effect of the addition of Cr, Mn, or Fe to Ni on the material's hydrogen solubility are investigated to establish guidelines for designing materials authorized to use in high-pressure hydrogen environments. The exposure to 100 MPa hydrogen gas at 160 °C reveals that the addition of 30 wt%Fe to Ni decreases the hydrogen solubility by 40%, while the addition of 20 wt%Cr to Ni increases it by 65%. Surprisingly, incorporating 20 wt%Mn causes a remarkable increase of 992%. By employing a combined approach of a random alloy model based on the special quasi-random structure and first-principles calculations, we are able to semi-quantitatively predict the effects of these alloying elements on hydrogen solubility. Moreover, the deconvolution of hydrogen bonding energy into its volumetric, mechanical, and chemical components clarifies that the significant impact of Mn is primarily attributed to a substantial expansion of the lattice constant.