Grain junctions

Figure 14.9 shows a three-grain junction on the surface of polycrystalline AI2O3 after high-temperature annealing. Each grain surface has a different inclination... 

However, Plateau s laws are not obeyed by the grain boundary structure in the special polycrystal in Fig. 15.15. To achieve local equilibrium at all grain junctions, so that Plateau s laws are obeyed, the faces of each grain must be curved [31]. A boundary structure in which all junctions obey Plateau s laws is presented in Fig. 15.16, which shows a polycrystal consisting of six grains that meet at four vertices. Each grain fully occupies one face of the polycrystal. As in Fig. 15.15,... 

FIGURE 16,18 Mechanism for pore detachment from the grain boundary consisting of (a) a pore at a three grain junction, (b) a pore at a two grain junction, and (c) a pore detached from the grain boundsuy. Taken from Fang and Palmour [41]. Eeprinted by permission of the American Ceramic Society. 

Dihedral angle of liquid on triple grain junction... 

Figure 14.1 (a) Charge exchange associated with the chemisorption of oxygen at the surface of an n-type semiconductor and the potential distribution across a grain junction,... 

Fig. 48. Composition profile across the grain-junction for a ternary Nd-Fe-B alloy. The arrows indicate the extent of the intergranular region. (After Rames et al. 1987.)...

Pores at grain boundaries and other grain junctions... 

Figure 8.15 Energy-dispersive X-ray spectra collected from glass pockets at triple grain junctions in two samples with additives of 6.25 wt% Y2O3-1.0wt% AI2O3 and 4.0wt% Y203-2.8wt% AUO3. The Al concentration was...

Figure 13.12 Two-grain junction cavities observed in SN 88 after creep at 1250°C under stress of 180 MPa after 868 h [37],...

Taking into account that, for polycrystals, the applied stress is one-third of the shear stress acting on the pile-up plane, the relationship between the shear stress concentration (x) and the applied stress a (x/a) must lie in the range between 40 and 75, although this would be too large to be explained by the stress concentration induced at multiple-grain junctions during GBS. Clearly, the dislocations reported by... 

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