Recovery of Quenched-in Vacancies of TiC_1−x

Abstract

The electrical resistivity of TiC_1−x (x=0.6-0.9) in the range from room temperature to 1273 K was measured, and a recovery stage and the activation energy of the migration of vacancies were determined after quenching from 2000 K. Specimens were prepared from buttons manufactured by plasma-jet melting.
All specimens except that of TiC_0.9 revealed the order-disorder transformation above 873 K in the electrical resistivity. The variation of resistivity due to the transformation decreased with the decrease of a value of x in TiC_1−x. Apparent activation energies obtained by the slope ratio method yielded values from 18 to 167 kJ/mol with increasing measuring temperature because of the variation of entropy accompanying the transformation. A rather reasonable value of 220 kJ/mol was assigned from the rate constant of the recovery at higher temperatures. From this value it is concluded that the recovery step obtained in this experiment is caused by the migration of carbon accompanied by the order-disorder change.