First-principle Study on Effects of Hydrogen on Mechanical Properties of γ′-Ni₃Al

At room temperature, hydrogen atom may cause embrittlement of γ'-Ni₃Al due to the reaction between the water vapor in air and Al in γ'-Ni₃Al. However, the atomic-scale embrittlement mechanisms remain unclear. First-principle calculations were utilized to analyze the evolution of mechanical properties such as the modulus and Poisson's ratio of γ'-Ni₃Al as a function of hydrogen content, and the atomic-scale mechanisms of hydrogen-induced embrittlement on γ'-Ni₃Al were investigated. The results indicate that hydrogen atoms in γ'-Ni₃Al preferentially accumulate in the octahedral sites formed by face-centered cubic Ni atoms. As the hydrogen content in γ'-Ni₃Al increases, both the strength and brittleness rise. Hydrogen atoms reduce the cohesion between Ni and Al atoms, thereby degrading the toughness of γ'-Ni₃Al and leading to material embrittlement.