Investigation of the kinetics of the isothermal peritectoid formation of Zr 3Al and U 3Si

Abstract

In the present work the kinetics of the isothermal peritectoid transformation have been critically evaluated in the zirconium/Zr 2Al partial system reported previously. In addition, the isothermal peritectoid reaction has been experimentally studied as a function of time from the coarsened U 3Si 2 precipitate/uranium matrix system using optical microscopy. The plots of the Austin-Rickett equation indicated that the time exponents are 2.5 and 1.5 in the early and in the later stage of the isothermal peritectoid reaction, respectively. Also, the impingement exponent was found to be 2. The experimental results indicated that the peritectoid transformation proceeds by nucleation and diffusion-controlled growth in the early stage and by diffusion-controlled growth without nucleation in the later stage, from which formulae describing the isothermal peritectoid transformation are derived.