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Umbral de la cerradura y morfología en la fusión láser revelada por imágenes de rayos X de ultra alta velocidad
Ross Cunningham1, Cang Zhao2, Niranjan Parab2
1Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA, USA.
Science (New York, N.Y.)
|February 23, 2019
Resumen
Las imágenes de rayos X de ultra alta velocidad revelan la dinámica del agujero de la cerradura durante la fusión del metal con láser en la fabricación aditiva. Este estudio cuantifica las depresiones de vapor, cruciales para comprender los procesos de impresión 3D.
Área de la Ciencia:
- Ciencias de los materiales
- Ingeniería de fabricación
- La física
Sus antecedentes:
- La fabricación aditiva de metales, específicamente la fusión en lecho de polvo láser, se basa en la fusión controlada.
- Se sabe que las depresiones de vapor, o agujeros de cerradura, ocurren durante la soldadura con láser, pero su dinámica en la fabricación aditiva no se visualiza bien.
- La comprensión de la formación de agujeros de cerradura es fundamental para el control del proceso y la calidad de las piezas.
Objetivo del estudio:
- Visualizar y cuantificar directamente la morfología y la dinámica de las depresiones de vapor (agujeros de cerradura) durante la fusión láser de metales.
- Determinar las condiciones en las que se forman los agujeros de cerradura en la fusión con lecho de polvo láser.
- Para aclarar los mecanismos físicos que rigen la formación y la estabilidad de los agujeros de cerradura.
Principales métodos:
- Utilizó imágenes de rayos X sincrotrón de ultra alta velocidad con rayos X de alta energía.
- Se ha investigado la fusión láser de metales en condiciones relevantes para la fusión en lecho de polvo láser.
- Analizó la morfología y la dinámica del agujero de la cerradura a través de un rango de potencia láser y velocidades de escaneo.
Principales resultados:
- La visualización directa confirmó la presencia de agujeros de cerradura en todo el rango de potencia y velocidad de escaneo utilizado en la fusión de lecho de polvo láser.
- Se identificó un umbral claro en la densidad de potencia del láser para la transición del modo de conducción al modo de agujero de cerradura.
- La transición a la formación de agujero de cerradura sigue una secuencia: vaporización, depresión superficial del líquido, inestabilidad y formación de agujero de cerradura profundo.
Conclusiones:
- La formación de agujeros de cerradura es frecuente en la fusión de lecho de polvo láser y se rige por la densidad de potencia del láser.
- La visualización directa proporciona una base física para la comprensión y el control de los procesos de impresión tridimensional.
- Esta investigación ofrece una visión crítica de la física fundamental de las interacciones láser-metal en la fabricación aditiva.
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