The kinetics of pressure induoed fcc-bcc transformation in ytterbium

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

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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: Article
Uncontrolled Keywords: kinetics;Fcc-bcc transformation;ytterbium.
Subjects: AERONAUTICS > Aeronautics (General)
AERONAUTICS > Aerodynamics
Depositing User: M/S ICAST NAL
Date Deposited: 03 Nov 2006
Last Modified: 19 Aug 2015 05:03

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