A method for analyzing the mechanics of sintering of a single grain boundary was developed. The translational motion and rotation of particles in sintering were influenced by the grain-boundary diffusion coefficient and energy; both being dependent upon the crystallographic orientation. Model experiments on gold were compared with simulation results in order to determine the depth of the cusps on the plot of grain-boundary energy versus misorientation angle, the grain-boundary diffusion coefficients and the surface diffusion coefficient. An experimental method was proposed for analyzing the mechanics of sintering of a single grain boundary by using specimens fabricated by focused ion beam micromachining. A self-consistent theoretical model for the evolution of neck curvature was developed which considered rotation, shrinkage and asymmetrical neck growth. The micro-specimen had a rectangular grain boundary between U-shaped notches. The sintering of the micro-specimen could be analyzed more easily than that of the classic two-sphere model. The linear velocity was driven by the sintering force, which was a function of neck curvature. The variation of dDgb in various grain boundaries of Au was determined from the linear velocity. The rotation was driven by torques arising from anisotropic cgb and asymmetrical neck shape. A method to estimate cgb(h) was developed in order to reveal the depth of shallow cusps at specific h-values. The torque induced by the asymmetrical neck shape could be ignored in the vicinity of a deep cusp.

Direct Observation of Sintering Mechanics of a Single Grain Boundary. F.Wakai, H.Fukutome, N.Kobayashi, T.Misaki, Y.Shinoda, T.Akatsu, M.Sone, Y.Higo: Acta Materialia, 2012, 60[2], 507-16