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Interaction of carbon with dislocations in tungsten.

Gray, R. J. (1970) Interaction of carbon with dislocations in tungsten. Doctoral thesis, University of Surrey (United Kingdom)..

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The interaction of carbon atoms with dislocations in tungsten has been investigated using the techniques of tensile testing and low frequency internal friction. The investigation involved the study of strain-ageing, the carbon Snoek peak and a previously reported "cold-work peak". It has been shown that at temperatures above 550°C, carbon in quenched tungsten causes strain-ageing the rate of which may be expressed in terms of the kinetics of Cottrell and Bilby. The apparent activation energy of yield point return (63 +/- 3 kcal/mole) is considerably higher than that for carbon diffusion (43 +/- 2 kcal/mole) estimated from the position of the Snoek peak. This apparent discrepancy is explained either by the interaction of diffusing carbon atoms, or by the dissolution of carbides during the strain-ageing process. A quantitative model has been proposed to account for the latter possibility. The observed deviation from Cottrell-Bilby kinetics during the early stages of strain ageing of carbon doped, slowly-cooled tungsten has been attributed to the occurrence of dislocation recovery preceding the pinning of dislocations. An internal friction peak observed at temperatures between 550° and 600°C during the heating of cold-worked tungsten containing carbon has been shown not to be a relaxation peak, it is accounted for in terms of the change in the rate of recovery of temperature-dependent dislocation damping as carbon atoms become mobile during the heating cycle.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Gray, R. J.
Date : 1970
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:17
Last Modified : 20 Jun 2018 11:39

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