The kinetics of pressure induoed fcc-bcc transformation in ytterbium

Divakar, C and Murali, Mohan (1984) The kinetics of pressure induoed fcc-bcc transformation in ytterbium. Journal of Applied Physics., 56 . pp. 2337-2340.

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    Abstract

    The kinetics data for the pressure-induced fcc-gt;bcc transformation in ytterbium under isobaiicisothermal conditions in the pressure range 3.3-4.6 GPa have been reported. The kinetics data satisfy Avrami equation: xA3; = 1 x2014; exp x2014; (t/r}n, where r and n are constants at a given pressure.Both r and xAB; decrease with increase in pressure, as given by the following relations:In r = (36.2 xB1; 1) - (6.8 xB1; 0.3]p, and xAB; = 1.36 + 0.55p - 0.168/?2, where/* is pressure (GPa). The activation free energy for the combined process of nucleation and growth has been estimated from the r x2014; p data and is found to decrease with increase in pressure. The activation free energy varies from 16 kcal mol * at 3.3 GPa to 11 kcal mol1 at 4.6 GPa. The activation enthalpies at 3.3,3.6, and 3.8 GPa have been determined by measuring r at different temperatures. The activation volume is x2014; 17 cm3 mol! at 300 K. It is estimated from the r x2014; p data that fcc-bcc13; transformation under shock loading will-occur at about 7 GPa.

    Item Type: Journal Article
    Uncontrolled Keywords: kinetics;Fcc-bcc transformation;ytterbium.
    Subjects: AERONAUTICS > Aeronautics (General)
    AERONAUTICS > Aerodynamics
    Division/Department: Materials Science Division, Materials Science Division
    Depositing User: M/S ICAST NAL
    Date Deposited: 03 Nov 2006
    Last Modified: 24 May 2010 09:51
    URI: http://nal-ir.nal.res.in/id/eprint/3091

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