Segunda aproximación en coalescencia perturbada aplicada a una aleación de Fe-Mn-Ti-Si
Fecha
2017-06-20
Autores
Leiva Stable, Angel Luis
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Editor
Universidad Central “Marta Abreu” de Las Villas
Resumen
Comprobada experimentalmente la influencia de una segunda transformación de fase sobre el proceso de Maduración de Ostwald y la desviación de la función de distribución real del sistema de precipitados respecto al caso libre (teoría de Lifshitz-Slezov-Wagner); se pudo resolver la ecuación de continuidad a través del método de aproximaciones sucesivas. El método iterativo aplicado a la primera aproximación para los distintos tiempos de revenido isotérmico mostró una significativa mejoría en la descripción de los histogramas experimentales cuando existe una mayor influencia de la segunda transformación de fase. Se realizó el cálculo de la segunda aproximación del esquema de aproximaciones sucesivas de Picard, mostrándose, que la mejoría en la descripción de los histogramas experimentales de los precipitados metaestables e isomorfos de Fe3Si se logra con los procesos iterativos y no con el cálculo de términos más elevados en la serie se aproximaciones. Se logró calcular para cada tiempo de revenido isotérmico, la constante de velocidad en la ley de crecimiento del radio crítico del sistema de precipitados, el volumen total transformado de la segunda fase y su radio reducido máximo.
The influence of a second phase transformation on the Ostwald process and the deviation of the real distribution function of the precipitate system from the free case (Lifshitz-Slezov-Wagner theory) were experimentally verified; it was possible to solve the continuity equation through the method of successive approximations. The process of iterative improvement of the first approximation for the different times of isothermal tempering showed a significant improvement in the description of the experimental histograms when there is a greater influence of the second phase transformation. The calculation of the second approximation of Picard's successive approximation scheme was carried out, showing that the improvement in the description of the experimental histograms of the metastable and isomorphic precipitates of Fe3Si is achieved with the iterative processes and not with the calculation of more terms High in the series are approximations. The rate constant in the growth rate of the critical radius of the precipitate system, the total transformed volume of the second phase and its maximum radius were calculated for each isothermal tempering time.
The influence of a second phase transformation on the Ostwald process and the deviation of the real distribution function of the precipitate system from the free case (Lifshitz-Slezov-Wagner theory) were experimentally verified; it was possible to solve the continuity equation through the method of successive approximations. The process of iterative improvement of the first approximation for the different times of isothermal tempering showed a significant improvement in the description of the experimental histograms when there is a greater influence of the second phase transformation. The calculation of the second approximation of Picard's successive approximation scheme was carried out, showing that the improvement in the description of the experimental histograms of the metastable and isomorphic precipitates of Fe3Si is achieved with the iterative processes and not with the calculation of more terms High in the series are approximations. The rate constant in the growth rate of the critical radius of the precipitate system, the total transformed volume of the second phase and its maximum radius were calculated for each isothermal tempering time.
Descripción
Palabras clave
Modelo Matemático, Método de Aproximaciones Sucesivas, Transformación de Fase, Aleaciones Martensíticas, Estado Sólido, Coalescencia