Pressure-induced alpha-omega transformation in titanium Features of the kinetics data

Singh, AK and Mohan, M and Divakar, C (1983) Pressure-induced alpha-omega transformation in titanium Features of the kinetics data. Journal of Applied Physics, 54. pp. 5721-5726. ISSN 0021-8979

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Use is made of the increase in the electrical resistance of the specimen associated with the alpha-omega transformation in Ti in order to obtain the fraction zeta of the omega phase as a function of time under isobaric-isothermal conditions in the pressure range 4-9 GPa and at 300 + or - 3 K. Over the entire pressure range, zeta-t data fit an equation of the form zeta = 1-exp-(t/tau) to the n power, where tau and n are constants at a given pressure. The results suggest that tau decreases rapidly and n slightly with an increase in pressure. An analysis of tau-p data reveals that the activation free energy for the total process is very high at low pressures and decreases rapidly with increasing pressure and that the activation volume in the 6-9 GPa range is -4.3 cu cm/mol. The activation enthalpy is obtained by measuring tau at different temperatures; the average value in the pressure range 5-8 GPa is 12 + or - 0.5 kcal/mol.

Item Type: Article
Uncontrolled Keywords: Activation energy;Electrical resistance;Phase transformations;Pressure effects;Titanium;Close packed lattices;Enthalpy;Hexagonal cells;Kinetics;Nucleation
Subjects: CHEMISTRY AND MATERIALS > Metals and Metallic Materials
Depositing User: Ms. Alphones Mary
Date Deposited: 28 Jan 2006
Last Modified: 24 May 2010 04:09

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