Mechanical properties of as-fabricated and 2300 °C annealed tungsten wire tested up to 600 °C

Terentyev, D.; Riesch, J.; Lebediev, S.; Bakaeva, A.; Coenen, J. W.

doi:10.1016/j.ijrmhm.2017.03.011

Cited by 37 publications

(40 citation statements)

References 20 publications

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“…The tensile mechanical properties of pure W and K-doped wires were studied at room and elevated temperatures by groups of Riesch [18][19][20][21] and Terentyev [22][23][24][25]. The primary conclusion regarding the potassium doping that can be drawn from those studies is that it helps suppressing massive grain growth at least up to 1600°C for 30 min, remaining ductile at room temperature with ultimate tensile strength exceeding 1 GPa.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical and microstructural properties of tungsten fibers in the as-produced and annealed state: Assessment of the potassium doping effect

Terentyev

Tanure

Bakaeva

et al. 2019

International Journal of Refractory Metals and Hard Materials

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Due to its high strength and low temperature ductility, tungsten fibers (W f) have been widely used as reinforcement elements in metallic, ceramic and glass matrix composites to improve the strength, toughness and creep resistance. Materials designed for future fusion reactors also utilize the option of W f reinforcement, i.a. with a copper (W f /Cu) or tungsten (W f /W) matrix. W f /W composites are being intensively studied as risk-mitigation materials to replace bulk tungsten which is susceptible to embrittlement induced by neutrons resulting from fusion reaction. Operation of W f /W in high temperatures (up to 1300°C and even higher) fusion environment implies a risk of recrystallization and grain growth, which dimishes the attractive properties of tungsten fibers. In this work, we assess this modification of micro-mechanical and microstructural properties of tungsten fibers by means of nanoindentation, scanning electron microscopy, electron back-scattering diffraction analysis and corelate it with the ultimate tensile strength and fracture modes observed in the tensile tests. Both pure W and pottasium doped wires in the as-fabricated and annealed states are investigated and the results were compared with bulk tungsten, also exposed to several annealing temperatures. The results highlight the postive impact of potassium doping which shifts the threshold temperature for the grain growth by about 600°C compared to pure tungsten wire.

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Section: Introductionmentioning

confidence: 99%

Micromechanical and microstructural properties of tungsten fibers in the as-produced and annealed state: Assessment of the potassium doping effect

Terentyev

Tanure

Bakaeva

et al. 2019

International Journal of Refractory Metals and Hard Materials

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“…Both, pure and K-doped tungsten wires show exceptional ductility [23] and significant strength (due to the Hall-Petch effect) [24] at room temperature, properties important for facilitating toughening mechanisms of Wf/W through the crack bridging effect as well as the fiber deformation effect [25]. Furthermore, studies regarding the mechanical response and plastic deformation at elevated temperatures showed that the wire can keep its valuable properties [26,27]. Additionally, some investigations dealt with the question of the effect of annealing on tensile properties of pure [28] and potassium doped tungsten wire [29], interconnecting in such a way general microscopic features to different material responses occurring in the experiment.…”

Section: Introductionmentioning

confidence: 99%

The effect of heat treatments on pure and potassium doped drawn tungsten wires: Part I - Microstructural characterization

Nikolić

Riesch

Pippan

2018

Materials Science and Engineering: A

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Advanced tungsten fibre-reinforced composites (Wf/W), showing pseudo ductile behaviour even at room temperature, are a promising option for future fusion reactors as the intrinsic brittleness of tungsten can be mitigated effectively. The drawn tungsten wires used as reinforcements are the key component of the composites, thus their mechanical properties and thermal stability define the allowed operation / fabrication temperature of the composite material itself. In this work, a comprehensive characterization of the pure and potassium doped tungsten wires was performed, focusing on the influence of various heat treatments on different microstructural features (nature of grain boundaries, grain shape and size, texture analyses) and mechanical properties. Annealing in the temperature range from 900-1600°C enables the investigation of the microstructural stability of the two materials and arising annealing phenomenarecovery, recrystallization and grain growth. The results demonstrate that the pure tungsten recrystallizes fully in the temperature range 1300-1500°C accompanied with tremendous coarsening and a complete loss of the initial fibrous, elongated grain structure. In contrast to this, potassium doped wire shows superior high temperature properties, where performed heat treatments cause only milder microstructural changes, consequently suppressing recrystallization and grain growth to temperatures well above the investigated ones. Furthermore, hardness measurements and observed softening complement the discussion of the grain morphology evolution.

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“…W-fiber (containing K, W f )-reinforced composites could show pseudo-ductility even at RT. Furthermore, not only the K-doped wires annealed at 2573 K exhibited much low fracture stress, but also the fracture mechanism also differed, namely: fracturing (ductile necking) above 573 K and fracturing (brittle cleavage) below 573 K. K-doping to the wires did not drastically alter the mechanical behaviors and the fracture would occur by grain delamination and elongation [34].…”

Section: Mechanical Properties Of Wkmentioning

confidence: 95%

“…7. The inset displays the zoom of the yield point area at which the wires annealed from 2173 to 2373 K [34,35,63]. Their works interpreted the role of K-doping on the improvement of the mechanical properties of W wires and gave an indication for the service temperature range of W f /W composites [35].…”

Section: Mechanical Properties Of Wkmentioning

confidence: 99%

“…The accompanied stress concentration makes a significant reduction in toughness. Tungsten-potassium or potassium-doped tungsten (WK), which brings in nano-sized K bubbles to pin GBs and dislocations, and simultaneously enhances the toughness and strength, is of great importance in PFMs [12,13,16,[27][28][29][30][31][32][33][34][35]. The main mechanical properties and preparation of WK are reviewed in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Tungsten–potassium: a promising plasma-facing material

2019

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Tungsten-potassium (potassium-doped tungsten or WK), initially known from the electric filament industry, is a promising plasma-facing material (PFM) in future fusion facilities like International Thermonuclear Experimental Reactor (ITER). However, the brittle nature of W and irradiation-induced defects of WK materials may result in a risk of deuterium-tritium reaction failure in fusion reactors. Previous studies revealed that advanced W with ultrafine grains and nanostructures might be able to address these problems. However, K-doped W, a rapidly developed material for PFMs, lacks a systematical summary. In this review, we firstly describe the powder metallurgy and plastic deformation for the preparation of WK. Then, the mechanical properties of WK and thermal shock resistance results are reviewed. Important issues such as irradiation damages from neutron, heavy ion, and plasma (H isotope or He) irradiation are also discussed. Hitherto, WK under irradiations shows comparable or even better performances compared with other counterparts such as ITER grade pure tungsten. This review could be benefitial to the future efforts of improving the ductility and irradiation tolerance of WK materials.

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Mechanical properties of as-fabricated and 2300 °C annealed tungsten wire tested up to 600 °C

Cited by 37 publications

References 20 publications

Micromechanical and microstructural properties of tungsten fibers in the as-produced and annealed state: Assessment of the potassium doping effect

Micromechanical and microstructural properties of tungsten fibers in the as-produced and annealed state: Assessment of the potassium doping effect

The effect of heat treatments on pure and potassium doped drawn tungsten wires: Part I - Microstructural characterization

Tungsten–potassium: a promising plasma-facing material

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