Surface energy and structure of crystal boundaries in metals

The variation of boundary energy $\gamma _{R}$ in lead with the difference of orientation $\theta $ was determined using the methods previously described for tin. It was found that the energy decreases progressively as the difference of orientation decreases below about 16 degrees. The curve relating energy with difference of orientation extrapolates to zero energy at zero angle. These results agree qualitatively with those of tin and offer further strong support for the 'transitional lattice' theory of the crystal boundary. Straight-line plots of log $\theta $ against $\gamma _{R}$/$\theta $ were obtained for lead and tin. These results are closely consistent with Shockley and Read's theoretical predictions based on a dislocation model of the transition boundary.