DISSOCIATION AND MECHANICAL PROPERTIES.DISLOCATION SPLITTING AND THE PLASTIC GLIDE PROCESS IN CRYSTALSReport as inadecuate




DISSOCIATION AND MECHANICAL PROPERTIES.DISLOCATION SPLITTING AND THE PLASTIC GLIDE PROCESS IN CRYSTALS - Download this document for free, or read online. Document in PDF available to download.



Abstract : This paper is aimed at a review of the lattice-dislocation interaction, and more specially to the kind of interaction which stems from the splitting of the dislocation core. Two quite different situations are discussed whether the core is dissociated off the glide plane, or not. In the first case, a number of various cases is reviewed, which all are intimately connected : crystallographic slip in b. c. c. metals, prismatic-pyramidal slip in h. c. p. metals, Lomer-Cottrell barriers in the f. c. c. structure and also some non metallic bonded crystals : tellurium and the brittleness of α-sulphur crystals. Finally, the general models proposed for modelling dislocation mobilities fall in two classes : whether a higher energy core configuragion must be reached in order for the dislocation to start slipping, or, in contrary, the core splits wider in this plane thus decreasing its energy. The case of a core dissociated in the glide plane is also considered in compounds where a -synchroshear mechanism- has been assumed. In general, only a simple glide process is involved, quite similar to the slipping of an extrinsic 2 ∇ stacking fault ribbon in the f. c. c. structure. Thermal help should be only needed for nucleating the suitable core of 2 Cδ-2 ∇-fault boundaries which avoids making wrong nearest neighbour bonds in certain structures. The activation energy for such viscous slip is evaluated, and is found to be stress-dependent. A similar treatment could apply for some non-stoichiometric compounds also.





Author: B. Escaig

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



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