Contribution of tilt boundaries to the total energy spectrum of grain boundaries in polycrystals

By measuring temperatures $T_w$ for the transition from the incomplete to complete wetting of grain boundaries in poly- and bicrystals, the width of the spectrum of tilt grain boundaries and their contribution to the total energy spectrum of grain boundaries in polycrystals have been experimentally estimated. It has been shown that the tilt grain boundaries correspond to a rather narrow (only $5$–$10\%$) portion in the total energy spectrum of grain boundaries in polycrystals. In metals with a low stacking fault energy (copper, tin, zinc), the tilt grain boundaries belong to $10$–$20\%$ of the grain boundaries with the highest transition temperatures $T_w$ (hence, with low energies). In a metal with a high stacking fault energy (aluminum), the values of $T_w$ for the tilt grain boundaries lie nearly in the middle between the minimum $(T_{w\min})$ and maximum ($T_{w\max}$) transition temperatures from the incomplete to complete wetting of grain boundaries. This means that grain boundaries with the structure corresponding to a lower energy than that of the symmetric twin boundaries (or stacking faults) can exist in aluminum.