Unified theory for the portevin-Le chatelier effect in substitutional alloys

Srinivasan, V (1973) Unified theory for the portevin-Le chatelier effect in substitutional alloys. Technical Report. National Aerospace Laboratory, Bangalore, India.

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    Abstract

    A comprehensive theory of dynamic strain ageing is 13; formulated to explain the Portevin-Le Chatelier effect in13; substitutional alloys. This theory leads to explicit expressions for the^ kinetics of dynamic strain aging, It is assumed that dynamic strain aging will give rise to serrated flow if moving dislocations are immobilized by a critical size of their atmospheres. Postulating on the basis of available experimental evidence that moving dislocations and their average velocity depend on the applied strain rate and test temperature, relations are deduced from the kinetic13; equations to describe the effect of strain rate, temperature13; and solute concentration on the initiation of serrated flow.13; This theory is applied to the available experimental observations of serrated flow in aluminium-magnesium-zinc and goldindium alloys. Migration energies for the solute and single vacancies in the aluminium base alloy are evaluated to be 0.5 and 0.7 eV respectively. It is suggested that magnesium with a migration energy of 0.55 eV causes the necessary dislocation locking for the occurrence of serrated flow in aluminium magnesium-zinc alloy, In addition, the present model suggests that the average dislocation velocity in gold-indium alloy should decrease with solute concentration as V = (Const) CQ -2/3 during dynamic strain ageing.

    Item Type: Proj.Doc/Technical Report (Technical Report)
    Uncontrolled Keywords: Tensile strain;Portevin-Le;Dynamic strain;Substitutional alloys;Serrated flow;Experimental data;linear plots
    Subjects: CHEMISTRY AND MATERIALS > Metals and Metallic Materials
    CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
    Division/Department: Materials Science Division
    Depositing User: M/S ICAST NAL
    Date Deposited: 22 Dec 2006
    Last Modified: 24 May 2010 09:54
    URI: http://nal-ir.nal.res.in/id/eprint/3803

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