Grain and subgrain boundaries in ultrafine-grained materials

Mechanical properties and microstructural evolution during multi-pass ECAR of Al 1100–O alloy

“…These dislocation cells are not well developed because many tangled dislocations still remain within the cell interiors and have yet to move to the already existing cell boundaries or to form new dislocation walls to subdivide the cell into smaller ones [31]. This is in good agreement with previous works [32][33][34][35][36][37]. From Fig.…”

“…6c which is the TEM micrograph for seven passes processed sample, there is a higher fraction of UFGs with an average grain size of 850 nm and clear grain boundaries with a high density of dislocations in the cell boundaries. The subgrains tend to be elongated same as previuos reports on ECAP [30,32]. The dislocation density inside the grains is very low in the sample processed through seven pass as can be seen in other SPD methods [29,30,32,38].…”

Predicting grain refinement by cold severe plastic deformation in alloys using volume averaged dislocation generation

“…HPT, ECAP and cold rolling of pure Al all result in subgrain sizes that are about 0.7 to 2 μm, which is 2 to 4 times smaller than the present model. Experiments have shown that in high purity Al deformed by ECAP up to 4 passes there are hardly any HAGBs [100]. Thus the reason for deviations from the model is that in pure Al θ is much smaller than the value of 27° that was taken in the model.…”

Gradual formation of nano/ultrafine structure under accumulative press bonding (APB) process

“…3 employed and these are recognized as the bottom-up and the top-down approaches [9,10]. In the bottom-up approach, UFG/NC materials are produced by assembling individual atoms or by consolidating nanoparticulate solids.…”

“…ACCEPTED MANUSCRIPT 10 3.1.4. Grain refinement mechanisms Figure 8 illustrates, in a simplified way, the evolution of the microstructure leading to the ultrafine equiaxed grains.…”