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Mayor resistencia y ductilidad en una aleación de alta entropía a través de complejos de oxígeno ordenados
Zhifeng Lei1, Xiongjun Liu1, Yuan Wu1
1Beijing Advanced Innovation Center for Materials Genome Engineering, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, China.
Nature
|November 16, 2018
Resumen
El oxígeno ahora puede mejorar la resistencia y la ductilidad del metal simultáneamente en aleaciones de alta entropía (HEAs). Este estudio revela complejos de oxígeno ordenados, un nuevo estado, rompiendo la tradicional compensación fuerza-ductilidad en materiales metálicos.
Área de la Ciencia:
- Ciencias de los materiales
- Trabajos de metalurgia
- Química del estado sólido
Sus antecedentes:
- El oxígeno es típicamente una impureza intersticial en los metales, causando fragilidad.
- Los métodos tradicionales de refuerzo de metales con oxígeno conducen a una pérdida de ductilidad.
- Las aleaciones de alta entropía ofrecen una plataforma única para explorar nuevos mecanismos de fortalecimiento.
Objetivo del estudio:
- Investigar la formación y los efectos de los complejos de oxígeno ordenados en aleaciones de alta entropía.
- Determinar si estos complejos pueden mejorar simultáneamente la resistencia y la ductilidad.
- Para aclarar el mecanismo de fortalecimiento mediado por estos complejos de oxígeno ordenados.
Principales métodos:
- El dopaje de un modelo TiZrHfNb HEA con el 2,0 por ciento atómico de oxígeno.
- Caracterización de complejos de oxígeno utilizando imágenes y análisis a nanoescala.
- Pruebas de tracción para evaluar las propiedades mecánicas (resistencia y ductilidad).
- Análisis del comportamiento de la dislocación y los mecanismos de deformación.
Principales resultados:
- Formación de complejos de oxígeno ordenados a nanoescala dentro de la matriz HEA.
- Mejora significativa en la resistencia a la tracción (48,5%) y la ductilidad (95,2%) en el HEA dopado con oxígeno.
- Se ha observado una ruptura de la vieja relación resistencia-ductilidad.
- Identificación de un nuevo mecanismo de endurecimiento por deformación que implica cambios en el modo de cisallamiento por dislocación y multiplicación.
Conclusiones:
- Los complejos de oxígeno ordenados representan un nuevo estado de oxígeno intersticial en los HEAs.
- Esta nueva formación compleja aumenta simultáneamente la fuerza y la ductilidad, superando las limitaciones anteriores.
- Los hallazgos ofrecen una nueva estrategia para el diseño de materiales metálicos avanzados, en particular los que contienen Ti, Zr e Hf.
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