A Theory of Slip-Band Formation and Work-Hardening in Face-Centred Cubic Metal Crystals

概要

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The theory of dislocation network in a face-centred cubic lattice put forward by H. Suzuki and the present author is extended to account for slip-band formation and work-hardening. It is shown that the elements of the network remained in an annealed crystal with sufficiently long life-time behave as slip sources, which emitt dislocation spirals in successive planes. The pole dislocations can form a sessile dislocation with the operative slip dislocation near the node, when they move for short distance with the help of the stress induced by the dislocation spirals of the operative slip system. Soon after yielding, accordingly, an equilibrium distribution of dislocation loops is likely formed around the segment of the sessile dislocation. The back stress is estimated by magnetic analogue, and linear hardening rate thus obtained can be compared with experiment. To form a fine structure of slip band is first required theoretically in the stage of rapid hardening from the relation between the mean density of activated sources in a slip zone and the mean separation distance between primary zones. This prediction shows a well accordance with experiment. While, it is found experimentally that fine slips are formed from surface sources and they are localized only in surface layers. This is also understood quite naturally from the present theory.
東北大学の論文