First-principles study of hydrogen incorporation into the Ti3SiC2/Zr heterojunction

The geometric structure, energy barrier and electronic properties of H-incorporated Ti3SiC2/Zr heterojunctions were investigated by first-principles calculations. Hydrogen atom settles in Ti3SiC2/Zr as interstitial impurity due to its small radius. Through calculating and analyzing the total energies of H-incorporated Ti3SiC2/Zr heterojunction, a much higher potential barrier (1.75 eV) was found when H atom diffuses from the interface into the Ti3SiC2 material than that (0.25 eV) into the Zr metal. The encountered potential barriers of H atom diffusing from vacuum into the Ti3SiC2 and Zr metal are also calculated, and they are both positive. These findings indicate that Ti3SiC2 is a suitable coating material to prevent the hydrogen embrittlement and corrosion in Zr metal. The electronic properties and valence bond properties of H-incorporated Ti3SiC2/Zr were analyzed based on the band structure, electronic density of states and Mulliken distribution. The calculated results show that all the H-incorporated Ti3SiC2/Zr heterojunctions exhibit metallic, covalent and ionic properties. These investigations may provide new insight into the underlying mechanisms of hydrogen diffusion in the Ti3SiC2/Zr heterojunction.