Quantitative Microstructure and Defect Density Analysis of Polycrystalline Tungsten Reference Samples after Different Heat Treatments
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A. Manhard
Abstract
In order to provide a solid basis for the correlation of microstructure and hydrogen isotope retention in tungsten, reference samples with different microstructures were prepared from a single batch of polycrystalline tungsten by standardised polishing and heat treatment procedures. Representative samples were analysed by scanning electron microscopy and scanning transmission electron microscopy as well as by electron backscatter diffraction. We show that if the annealing temperature is increased from 1 200 to 1 500 K, practically only the density of dislocations and grain boundaries with very small misorientations of less than 2° is reduced, while for annealing at 1 700 and 2 000 K, also the density of high-angle grain boundaries is reduced due to grain growth. Furthermore, the dislocation density is reduced by nearly two orders of magnitude compared to tungsten annealed at 1 200 K. We also comment on two different textures on the front and rear side of the samples that were observed both by X-ray diffraction and EBSD.
Kurzfassung
Um eine solide Basis für die Korrelation von Mikrostruktur und Wasserstoffisotop-Rückhaltung in Wolfram zu schaffen, wurden aus einer einzigen Fertigungscharge polykristallinen Wolframs durch standardisierte Polier- und Wärmebehandlungsverfahren Referenzproben mit unterschiedlichen Mikrostrukturen gefertigt. Repräsentative Proben wurden mittels Rasterelektronenmikroskopie, Rastertransmissionselektronenmikroskopie und Rückstreuelektronenbeugung analysiert. Es wird gezeigt, dass durch eine Erhöhung der Glühtemperatur von 1 200 auf 1 500 K praktisch nur die Dichte von Versetzungen und Korngrenzen mit sehr kleinen Missorientierungen von weniger als 2° reduziert wird, während beim Glühen bei 1 700 und 2 000 K aufgrund von Kornwachstum auch die Dichte der Großwinkel-Korngrenzen sinkt. Verglichen mit bei 1 200 K geglühtem Wolfram nimmt zudem auch die Versetzungsdichte um beinahe zwei Größenordnungen ab. Weiterhin werden zwei verschiedene Texturen auf der Vorder- und Rückseite der Proben besprochen, die durch Röntgenbeugung und EBSD entdeckt wurden.
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© 2015, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- The Interlamellar Spacing of Pearlite
- Quantitative Microstructure and Defect Density Analysis of Polycrystalline Tungsten Reference Samples after Different Heat Treatments
- Beware of Hot Tearing in Lifting Lugs – a Case Study in Mechanical Engineering
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- The Interlamellar Spacing of Pearlite
- Quantitative Microstructure and Defect Density Analysis of Polycrystalline Tungsten Reference Samples after Different Heat Treatments
- Beware of Hot Tearing in Lifting Lugs – a Case Study in Mechanical Engineering
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
