Physical and chemical properties of solid materials are strongly. influenced by the chemical composition of internal interfaces, One of the crucial parameters affecting interfacial chemistry is the atomic structure of the interface. Due to its importance. a considerable amount of work was done to elucidate the relationship between structure and chemical composition of interfaces. This article reviews the present understanding of an important and fundamental part of this relationship, namely, the structural aspects of grain boundary segregation. After a brief outline of grain boundary structure and geometry. thermodynamic approaches to describe grain boundary segregation are summarized and their application to materials is discussed. covering particular sites at a single grain boundary as well as the role of interfaces in polycrystals. Both the experimental evidence of grain boundary segregation anisotropy and the theoretical results of computer simulations of grain boundary segregation are summar...

Thermodynamics and structural aspects of grain boundary segregation

On the corrosion behaviour of ultra-fine grain copper

The corrosion properties of bulk nanocrystalline ingot iron (BNII) fabricated from conventional polycrystalline ingot iron (CPII) by severe rolling were investigated by means of immersion test, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) tests, and scanning electron microscopy (SEM) observation. These experimental results indicate that BNII possesses excellent corrosion resistance in comparison with CPII in acidic sulfate solution at room temperature. It may mainly result from different surface microstructures between CPII and BNII. However, the corrosion resistance of nanocrystalline materials is usually degraded because of their metastable microstructure nature, and the residual stress in nanocrystalline materials also can result in degradation of corrosion resistance according to the traditional point of view.

The electrochemical corrosion of bulk nanocrystalline ingot iron in acidic sulfate solution.

The extremely fine grain size of nanocrystalline (nc) metallic alloys results in significantly different mechanical, electrochemical and oxidation properties as compared to the coarse-grained alloys of the same composition. Although the synthesis and attractive mechanical properties of nanocrystalline materials have been investigated and reviewed in great depth, the high temperature oxidation and electrochemical corrosion of these materials has received limited attention. The difference in the active dissolution and passivation behavior of nc alloys as compared to their microcrystalline counterparts varies for each alloy system. However, a unified theory explaining these phenomena still eludes us. In this context, this article reviews the progress in the electrochemical corrosion behavior of different nanocrystalline alloys, and hence, develops a better understanding of the effect of grain size, composition, interfacial phenomena and selective dissolution on corrosion of nanocrystalline alloys. This review also presents the role of nanometric grain size and the associated increase in grain boundary diffusion on the high temperature oxidation of nc alloys. The attractive possibility of enhanced oxidation resistance at lower alloying additions as compared to the coarse-grained alloys has been discussed. Although the primary focus of the article is on ferrous alloy systems, however, the lead studies on the role of ultrafine grain size in oxidation/corrosion behavior of other alloys systems have also been reviewed.

https://link.springer.com/content/pdf/10.1007%2Fs11661-014-2452-5.pdf

Role of nanostructure in electrochemical corrosion and high temperature oxidation: A review

The mechanics and mechanisms of fracture in stress corrosion cracking of aluminium alloys

Intergranular stress corrosion cracking (SCC) of Cu–9 at.% Al alloy bicrystals with symmetrical [110] and [100] tilt boundaries has been investigated under constant applied stresses in an ammoniacal solution at 303 ± 2 K. The susceptibility, defined by the inverse of time spent for initiation and propagation of the brittle crack along the boundary, was found to be strongly dependent upon the misorientation. Susceptibility minima were found at misorientations where interfacial energy cusps have been often observed in copper and aluminium in the literature. The grain-boundary energy is considered to be one of the crucial factors which determine the susceptibility. It is suggested that the susceptibiliy is affected by the dislocation behaviour at a grain boundary. A stress field generated as a result of interaction between lattice dislocations and a grain boundary may reduce the resistance to intergranular SCC. The susceptibility rapidly decreases, most probably owing to the increase in dislocations...

S. Hashimoto

Papers

Stress corrosion cracking of [110] and [100] tilt boundaries of α-Cu-Al alloy