The valence electron structure analysis on the influence of hydrogen solid solution to the thermoplasticity of α-Ti and β-Ti

The thermo-hydrogen (THP) of titanium can improve the thermoplasticity performance by increasing volume fraction of the plastic phase, promoting the movement of dislocations and reducing the flow stress. It can significantly reduce the difficulty of titanium alloy hot working. Most of the explainations on THP remain at the grain and phase scale and some researches at the electron scale are not clear enough, which cannot fully reveal the mechanism of hydrogen induced thermoplasticity of titanium. Empirical electron theory (EET) of solids and molecules was applied to analysis the changes of valence electron structures when H dissolved into different interstices of α-Ti or β-Ti. Through bond length diffrence method (BLD), the the number of covalent bonding electron pairs between Ti-Ti, the energy of the chemical bond and the lattice electron density between glide planes were calculated, it can be got that the obvious decrease of he number of covalent bonding electron pairs and the energy of the chemical bond between Ti-Ti, and the increase of the lattice electron density between glide planes are the essential reasons of hydrogen induced thermoplasticity of titanium.