Role of Boundaries in Control of Deformation Rate and Strength of Crystalline Materials

Abstract:

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Plastic deformation of crystalline materials is not controlled by interaction among free dislocations only, but the interaction of free dislocations with internal boundaries. i) Low-angle boundaries: Modeling of deformation of pure materials with conventional grain size on the basis of structure evolution indicates that low-angle boundaries act as obstacles of free dislocations. The migration of the low-angle boundaries constitutes an essential recovery process determining the deformation resistance in the steady state. ii) High-angle boundaries: Severe plastic deformation transforms low-angle boundaries into high-angle ones. They differ in obstacle and recovery characteristics from low-angle boundaries, which explains the special properties of ultrafine-grained and nanocrystalline materials with regard to strength, strain rate sensitivity and ductility. iii) Phase boundaries in Ni-base superalloys enhance the strengthening by hard phases with strengthening by dense dislocation networks serving to reduce coherency stresses. It is concluded that internal boundaries play a crucial role in controlling the evolution of structure and strength in crystalline materials.

Info:

Periodical:

Materials Science Forum (Volumes 604-605)

Edited by:

Marcello Cabibbo and Stefano Spigarelli

Pages:

391-401

DOI:

10.4028/www.scientific.net/MSF.604-605.391

Citation:

W. Blum "Role of Boundaries in Control of Deformation Rate and Strength of Crystalline Materials", Materials Science Forum, Vols. 604-605, pp. 391-401, 2009

Online since:

October 2008

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