A united theory for the portevin-Le chateler effect in substitutional alloys

Srinivasan, V (1973) A united theory for the portevin-Le chateler effect in substitutional alloys. Technical Report. National Aeronautical Laboratory, Bangalore,India.

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    Abstract

    A comprehensive theory of dynamic strain ageing is13; formulated to explain the Portevin-Le Chatelier effecr in13; substitutional alloys. This theory leads to explicit expres-13; sions for the'kinetics of dynamic strain ageing. It is13; assumed that dynamic strain ageing 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 quot;sduced 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 aluminiummagnesium-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) C, during dynamic strain ageing.

    Item Type: Proj.Doc/Technical Report (Technical Report)
    Uncontrolled Keywords: Portevin-Le;Aluminium-magnesium-zinc;Gold-indium alloy
    Subjects: AERONAUTICS > Aerodynamics
    Division/Department: UNSPECIFIED
    Depositing User: M/S ICAST NAL
    Date Deposited: 17 Jan 2007
    Last Modified: 24 May 2010 09:54
    URI: http://nal-ir.nal.res.in/id/eprint/3912

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