Cinética de engrosamiento de precipitados coherentes en la aleación Fe-10 % Ni-15 % Al

The coarsening kinetics and the morphology evolution of the coherent β' (Fe, Ni)Al precipitates embedded in a ferritic matrix were studied in the aged Fe-10 % Ni-15 % Al alloy. Samples were solution treated at 1,100°C for 24 h and subsequently aged at 750, 850 and 920°C for different times. XRD, SEM and TEM results showed the following decomposition reaction after aging treatment, α_sss →α+β. Intragranular particles distribution changes from a random to an aligned on the elastically soft 〈100〉 crystallographic directions of the matrix. Additionally, the morphological evolution of the precipitates was as follows: spheres → cuboids → parallelepipeds → plates. The variation of the cube of mean radius of particles, r³, and the particle density as a function of time followed a linear relationship, as predicted by the Lifshitz, Slyosov and Wagner (LSW) theory for diffusion-controlled coarsening. The rate constant (K) increased with the aging temperature. The activation energy for coarsening process was determined to be about of 220 kJ/mol.