Grain Boundary Segregation in Nanocrystructured Metallic Materials

Abstract

The aim of this chapter is to shed light on the effects of grain boundary segregation on microstructural evolution in nanostructured metallic materials as well as on their mechanical properties. Several key topics will be covered. First, a brief explanation of mechanical stress-driven grain growth in nanostructured Al, Ni, and Cu thin films will be provided in terms of a deformation mechanism map. It will become clear that the excess energy of grain boundaries enable the nanostructured metals to suffer from significant microstructure evolution via dislocation-boundary interactions during plastic deformation even at room temperature. Manipulation of grain boundary structures/properties via dopants segregation at grain boundaries to inhibit grain coalescence associated with remarkably enhanced mechanical properties is then discussed in three representative binary Cu-based systems, i.e., Cu-Zr, Cu-Al, and Cu-W. This is finally followed by a summary of this chapter.

Effect of Multiply Twinned Ag(0) Nanoparticles on Photocatalytic Properties of TiO2 Nanosheets and TiO2 Nanostructured Thin Films

“…Figure 5 f also includes subunit T5, where the SF implies the dislocation lines, observed as a result of TB interaction. The HAADF-STEM examination confirmed that higher temperature was able to facilitate the progressive coalescence of two Ag (0) NPs into one larger Ag (0) NP with a fivefold twinned structure [ 49 ]. Additionally, we could suggest that the perfect anatase TiO 2 (101) may provide nucleation sites for the growth of Ag (0) NPs with a pentagonal bipyramidal structure ( Figure 5 c), which, unlike Ag (0) NPs with a planar (flat) geometry in Ag_TiO_LYO)/500 ( Figure 5 a–c), could support the improvement of the properties of Ag_TiO_LYO)/800 as a photocatalyst [ 50 ].…”