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<正> 3 晶界结构对力学性质的影响 晶界是固体材料中的一种面缺陷.由于晶界和位错以及其他缺陷和杂质之间的相互作用,

GRAIN BOUNDARY STRUCTURE AND ITS EFFECT ON MECHANICAL PROPERTIES OF POLYCRYSTALLINEMATERIALS (II)

Many experiments indicate that mechanical properties of polycrystal-line materials are strongly affected by the grain boundary (g.b.). In this paper, the theoretical and experimental work on g.b. structures and their effect on mechanical properties of polycrystalline materials is briefly reviewed. In the first part of this paper, the different models proposed for describing the g.b. structures are introduced, including the dislocation model for describing small angle g.b., the coincidence site lattice (CSL) model, O-lattice model and displacement shift completely (DSC) lattice theory, for describing large angle g.b.s. The atomic and electronic structures of g.b.s, as well as the cohesion and the energy of g.b.s are also discussed.In the second part, the effect of g.b. structures on mechanical "properties, such as strength, fracture toughness, creep, fatigue, intergranular fracture (stress corrosion cracking, hydrogen cmbrittlement, liquid metal corrosion etc) , is summarized. The grain boundary design and the nanocrystalline materials are also introduced, which are the recent development for improving the mechanical properties of polycrystalline materials by controlling the grain boundary structures.