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Abstract : Grain-boundary induced hardening mechanisms are illustrated by recent observations in silicon bicrystals. Basic features of grain boundary structure and grain boundary dislocations are given in the case of the Σ = 9 twin boundary. The dissociation of dislocations in grain boundaries and the possibility of direct dislocation transmission from one crystal to the other across the interface are discussed. At moderate temperatures, such mechanisms are difficult and not able to prevent the formation of work hardened regions in the neighbourhood of grain boundaries, right at the onset of plastic deformation. Those regions contain networks with Lomer-Cottrell locks and show evidence of profuse cross-slip. Large stress concentrations arise, that may be against the applied stress. The relevance of these findings for other kinds of grain boundaries and other materials is briefly discussed.

Keywords : bicrystals Cottrell atmospheres elemental semiconductors hardening silicon slip twin boundaries semiconductor grain boundaries hardening mechanisms grain boundary structure grain boundary dislocations twin boundary plastic deformation Lomer Cottrell locks cross slip Si bicrystals

Autor: A. George

Fuente: https://hal.archives-ouvertes.fr/


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