A time dependent kinetic small angle neutron scattering study of a novel YFe phase

Crystallization of amorphous Y67Fe33 into the YFe2 C15 Laves phase via a novel 'YFe' intermediate phase has been observed through to completion using time-resolved small angle neutron scattering (SANS). The nucleation and growth kinetics of the phase transformations have been studied at annealing temperatures below the crystallization temperatures for both the 'YFe' phase and the YFe2 phase. The SANS results agree with previously reported neutron diffraction and SANS data. At the annealing temperatures of 360, 370 and 380 degrees C, changes in the scattering intensity I (Q) occur as a result of the contrast between the amorphous matrix and the nucleating and growing Y and 'YFe' phases. Critical scattering occurs during each of the isotherms, relating to the full crystallization of Y67Fe33, and extrapolation gives a crystallization temperature of 382 degrees C. Beyond critical scattering, isotherms at 435, 450, and 465 degrees C reveal the details of the continuing transformation of the 'YFe' intermediate phase into the YFe2 C15 Laves phase.