next up previous
Next: GBS in (21) boundary Up: Grain Boundary Sliding Previous: General observations on GBS

GBS in (11) twin structure (Figure 7)

0.3truein The energy profile of GBS process in (11) twin structure (Figure 7) has two energy peaks and a energy valley between them. The first peak occurs when the shear displacement is about aCSL, where the atoms across the interface plane are at positions directly facing each other, and furthermore these atoms facing each other are in the same (110) plane. It can be seen that open circle is the exactly above open circle (filled circle is exactly above filled circle). In case II, the separation distances between atoms across the boundary is the smallest, and the corresponding energy value is the largest as seen in the energy plot. When the shear displacement is about aCSL (case IV in Figure 7), the atoms representative open circles (and filled) are directly above the filled (and open) circles across the boundary. This configuration corresponds to a set of atoms in adjacent (110) planes displaced by d220 amount in the z-direction. Though this configuration results in higher energy, it is still significantly less than that of case II where the atoms across the interface are in the same z-plane. Between these two high energy states (cases II and IV), there is an energy valley at the aCSL shear displacement (see case III in Figure 7). The atomic arrangement at this displacement forms a twin structure equivalent to the initial structure. Though the interface of the twin has shifted (from AA to BB) with d111 amount in the y-direction, this boundary has an energy equal to the initial twin structure.



Ping Dang
Wed Mar 12 14:52:36 EST 1997