Microstructural evolution in single tungsten fiber-reinforced tungsten composites during annealing: recrystallization and abnormal grain growth

Ciucani, U. M.; Haus, L.; Gietl, H.; Riesch, J.; Pantleon, Wolfgang

doi:10.1016/j.jnucmat.2020.152579

Cited by 9 publications

(2 citation statements)

References 35 publications

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“…All three orientation maps clearly reveal the microstructure of the matrix with large columnar grains having grown radially outwards during CVD, confirming the impression from figure 2.2a. This is similar to what has been observed previously in single fiber composites with and without oxide interlayers [9,10]. Even the same peculiar spatial arrangement of orientations can be recognized from the colors: Horizontally elongated grains appear red when the crystallographic direction along the x-axis is shown, indicating a preference for having a ⟨100⟩ direction along their growth direction.…”

Section: Resultssupporting

confidence: 88%

“…Such a cyclic fiber texture, different from a cyclic ring fiber texture, has not been observed before in single fiber model composites; they always showed a cyclic ⟨100⟩ ring fiber texture, even in the absence of any oxide interlayer [9,10]. Nevertheless, the reason for this specific texture occurring in the absence of an interlayer has to be linked to this absence establishing a direct interface between matrix and wire and the texture of the wire itself.…”

Section: As-processed State -Single Fiber Composite Without Interlayermentioning

confidence: 66%

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Recrystallization and grain growth in single tungsten fiber-reinforced tungsten composites

Wartacz,

Riesch,

Pantleon

et al. 2023

J. Phys.: Conf. Ser.

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High heat fluxes in future fusion reactors pose big challenges on the materials of plasma-facing components due to restoration processes occurring at high temperatures. Tungsten is considered most suitable as plasma-facing material. To overcome its inherent brittleness at low temperatures, tungsten fiber-reinforced tungsten composites are developed which contain ductile, potassium-doped, drawn tungsten wires in an undeformed tungsten matrix. Such composites show pseudo-ductile behavior, an improved toughness and a more controlled fracture compared to undeformed tungsten. Model systems containing a single fiber either without any interlayer or with an yttria interlayer between fiber and matrix are annealed and characterized by electron backscatter diffraction (EBSD) in order to investigate their thermal stability. The restoration process in wire and matrix differ from each other: Recrystallization followed by grain growth occurs in the deformation structure of the wire. Grain growth is the sole mechanism affecting the undeformed matrix. An yttria interlayer between fiber and matrix is supposed to separate the differently restoring microstructures from each other and thereby preserve the improved mechanical properties of the composite. The investigation focuses on characterizing the as-processed condition and the microstructural changes after annealing at 1450 °C for either four days or two weeks. After two weeks of annealing, grains in the region or the vicinity of the wire have coarsened so much that former fiber and matrix cannot be distinguished any longer; not even in a model composite with a 1 μm thick yttria interlayer.

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Section: Resultssupporting

confidence: 88%

Section: As-processed State -Single Fiber Composite Without Interlayermentioning

confidence: 66%

Recrystallization and grain growth in single tungsten fiber-reinforced tungsten composites

Wartacz,

Riesch,

Pantleon

et al. 2023

J. Phys.: Conf. Ser.

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Tungsten Wire—From Lamp Filaments to Reinforcement Fibers for Composites in Fusion Reactors

Riesch,

Fuhr,

Almanstötter

2024

Adv Eng Mater

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The use of drawn tungsten wire marked a breakthrough in electric lighting which led to a significant advancement in human society and technology. Nowadays, thermal light sources using tungsten filaments are being more and more replaced by semiconductor‐based light‐emitting diodes (LEDs). Despite the lower visibility of incandescent lamps in everyday life, new markets and applications for drawn tungsten wires are opening up, which makes this complex material a highly‐studied subject. One of these applications is the use of heavily drawn tungsten wires as high‐performance reinforcement fibers for new composites that can withstand the extreme environment present in a nuclear fusion reactor. The main advantage of tungsten wires for this class of composites is their ductility and high strength. It can be used to increase the high‐temperature strength of copper‐based heat sink materials as well as the fracture toughness of bulk tungsten considered for the use of highly loaded reactor wall components. These new applications for tungsten wire has also given new impetus to the study of their fundamental properties.

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Effect of hot-working process on interface structure and ductile-to-brittle transition temperature of tungsten alloy reinforced by Al2O3 particles

Wang

Dong

Wei

et al. 2022

International Journal of Refractory Metals and Hard Materials

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Microstructural evolution in single tungsten fiber-reinforced tungsten composites during annealing: recrystallization and abnormal grain growth

Cited by 9 publications

References 35 publications

Recrystallization and grain growth in single tungsten fiber-reinforced tungsten composites

Recrystallization and grain growth in single tungsten fiber-reinforced tungsten composites

Tungsten Wire—From Lamp Filaments to Reinforcement Fibers for Composites in Fusion Reactors

Effect of hot-working process on interface structure and ductile-to-brittle transition temperature of tungsten alloy reinforced by Al2O3 particles

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