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La heterogeneidad de la nucleación de banda de deslizamiento persistente y la evolución en metales a escala
Steven Lavenstein1, Yejun Gu1, Dylan Madisetti1
1Department of Mechanical Engineering, Whiting School of Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
Science (New York, N.Y.)
|October 9, 2020
Resumen
Las bandas de deslizamiento persistentes (PSB) se forman en los metales durante la carga cíclica. Este estudio revela que las PSB son comunes en la escala micrométrica, influyendo en el inicio de la fatiga y la falla del metal.
Área de la Ciencia:
- Ciencias de los materiales
- Ingeniería mecánica
- Trabajos de metalurgia
Sus antecedentes:
- El daño por fatiga en los metales implica un movimiento de dislocación irreversible, el inicio de grietas y la propagación.
- La comprensión de la transición de un estado libre de crack a un estado agrietado es un desafío significativo en la investigación de la fatiga.
- Las bandas de deslizamiento persistentes (PSB) son características microestructurales cruciales asociadas con esta transición durante la carga cíclica.
Objetivo del estudio:
- Investigar los mecanismos de formación y evolución de las bandas de deslizamiento persistente (PSB) utilizando experimentos de microfatiga in situ.
- Caracterizar la prevalencia y el comportamiento de las PSB a escala micrométrica.
- Para conectar los mecanismos de deformación a escala micrométrica con la falla de fatiga a gran escala en los metales.
Principales métodos:
- Se llevaron a cabo experimentos de microfatiga in situ para observar la formación de PSB.
- Se empleó un análisis microscópico para investigar los mecanismos de evolución de la PSB a escala micrométrica.
- Las tasas de acumulación de dislocación se midieron en la escala micrométrica y se compararon con muestras a granel.
Principales resultados:
- Se encontró que las bandas de deslizamiento persistentes (PSB) prevalecen en la escala micrométrica en metales bajo carga cíclica.
- Las tasas de acumulación de dislocación en la escala micrométrica son más bajas que en las muestras a granel, retrasando la nucleación de PSB.
- El estudio observó una evolución gradual y heterogénea de las PSB.
Conclusiones:
- Los hallazgos ponen de relieve la importancia de los fenómenos a escala micrométrica en los daños por fatiga.
- Los modelos existentes para la formación de PSB y el inicio de grietas en metales pueden necesitar refinamiento para incorporar una evolución gradual y heterogénea.
- La comprensión de los mecanismos de deformación a escala micrométrica es esencial para predecir la falla de fatiga a gran escala en los metales.
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