Estudio por medio de LIBS de la interdifusión entre aleaciones en base Zr y aceros inoxidables martensíticos de uso nuclear

Abstract

En este trabajo se empleó la espectroscopia de ablación inducida por láser [Laser Induced Breakdown Spectroscopy LIBS], para analizar pares de difusión del sistema Zr-2,5 por ciento Nb / acero inoxidable ASTM 410 M. A tal fin, se obtuvieron pares por difusión en alto vacío y posteriormente, se realizaron tratamientos térmicos a diferentes tiempos y temperaturas entre 600 y 900 grados C. Se puso en funcionamiento y se optimizaron los parámetros básicos de un equipo comercial de LIBS [Ocean Optics 2500+] para obtener la repetibilidad y reproducibilidad de los espectros de emisión con el fin de analizar los elementos presentes en distintos sectores de la muestra. Se trazaron perfiles de concentración de Zr, Fe, Nb, Cr principalmente, mostrando como avanzan estos elementos dentro de sus respectivas matrices y se aplicaron las soluciones de las ecuaciones de Fick a dichos perfiles para obtener valores cuantitativos de las velocidades de difusión de elementos rápidos como el Fe, Cr y Ni en la matriz de Zr-2,5 por ciento Nb; resultados que fueron similares a los obtenidos por trabajos similares utilizando otras técnicas de análisis. Adicionalmente se realizó el seguimiento de la evolución microestructural de los materiales base utilizados y del par de difusión. Como resultado final de este trabajo se aplicó por primera vez esta técnica a estudios de interdifusión en materiales nucleares, resultando una herramienta poderosa para futuros estudios en difusión.|In this work Laser Induced Breakdown Spectroscopy LIBS was used to analyze diffusion in Zr-2, 5 per cent Nb / stainless steel ASTM 410 M couples. They were obtained by means high vacuum annealing. Different thermal treatments at different times and temperatures between 600 and 900 C degrees were employed in order to analyze the behaviour of the couples. A commercial equipment LIBS Ocean Optics 2500+ was put into operation and basic parameters were optimized in order to improve good repeatability and reproducibility of the emission spectra of the elements involved in different areas of the sample. Concentration profiles of Zr, Fe, Nb and Cr were plotted, principally showing how these elements move in their respective matrices. Mathematical solutions for Fick's equations were applied to these profiles to obtain quantitative values of the velocities of fast diffusers such as Fe, Cr and Ni in the matrix of Zr-2, 5 per cent Nb. These results showed similar values to those obtained by using other analytical techniques. Additionally the evolution of the microstructure of the materials involved was tracked. As a final remark in this work, LIBS technique was applied for the first time to the study of interdiffusion studies in nuclear materials, showing to be a powerful tool for futures studies.

Tesis para optar al título de Magister en Ciencia y Tecnología de Materiales

In this work Laser Induced Breakdown Spectroscopy LIBS was used to analyze diffusion in Zr-2, 5 per cent Nb / stainless steel ASTM 410 M couples. They were obtained by means high vacuum annealing. Different thermal treatments at different times and temperatures between 600 and 900 C degrees were employed in order to analyze the behaviour of the couples. A commercial equipment LIBS Ocean Optics 2500+ was put into operation and basic parameters were optimized in order to improve good repeatability and reproducibility of the emission spectra of the elements involved in different areas of the sample. Concentration profiles of Zr, Fe, Nb and Cr were plotted, principally showing how these elements move in their respective matrices. Mathematical solutions for Fick's equations were applied to these profiles to obtain quantitative values of the velocities of fast diffusers such as Fe, Cr and Ni in the matrix of Zr-2, 5 per cent Nb. These results showed similar values to those obtained by using other analytical techniques. Additionally the evolution of the microstructure of the materials involved was tracked. As a final remark in this work, LIBS technique was applied for the first time to the study of interdiffusion studies in nuclear materials, showing to be a powerful tool for futures studies.