Improved pseudo-ductile behavior of powder metallurgical tungsten short fiber-reinforced tungsten (W/W)

Coenen, J. W.; Mao, Y.; Sistla, S.; Riesch, J.; Hoeschen, T.; Broeckmann, C.; Neu, R.; Linsmeier, Ch.

doi:10.1016/j.nme.2018.05.001

Cited by 43 publications

(45 citation statements)

References 26 publications

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“…A schematic drawing of the sintering mold systems is shown in Figure 1. Two different types of tool design are used: a) Graphite sheets are placed between punch and mixture, aiming to reduce the damage of the punch surface and to facilitate easier sample removal after the FAST process (Figure 1 Previous studies [6,21] revealed that, when the sample is sintered with a graphite foil, the tungsten fibers become brittle after sintering due to carbon contamination. By replacing the graphite foil with pure tungsten foil, this undesirable outcome is avoided.…”

Section: Composite Manufacturingmentioning

confidence: 99%

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

et al. 2019

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In future fusion reactors, tungsten is considered as the main candidate material for plasma-facing components. However, the intrinsic brittleness of tungsten is of great concern during operation. To overcome this drawback, tungsten fiber-reinforced tungsten composites (Wf/W) are being 2 developed relying on extrinsic toughening principles. Tungsten (W) fibers with extremely high tensile strength and ductility are used to reinforce a tungsten matrix. In this work, field assisted sintering technology (FAST) is used to produce Wf/W material. Mechanical characterizations including Charpy impact and 3-point bending tests are performed. Based on the 3-point bending test results, the Wf/W materials can facilitate a promising pseudoductile behavior even at room temperature, similar to fiber reinforced ceramic composites. Fracture energy density and fracture toughness together with the crack-resistance curves (R-curves) are measured. Compared to conventional pure tungsten, Wf/W shows significant improvement in fracture toughness.

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Section: Composite Manufacturingmentioning

confidence: 99%

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

et al. 2019

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“…The sintering tool system ( Figure 1) that is used in this study was similar to the one used in ref. [11]: 1) graphite sheets were placed between the mold and mixture, aiming to reduce the damage of the punch surface and to ease sample removal after the FAST process (Figure 1 left); 2) to separate the powder-fiber mixture and the graphite mold, W foils with 25 μm thickness were used, to reduce the carbon contamination of the W fibers (Figure 1 right).…”

Section: Composite Manufacturingmentioning

confidence: 99%

“…With W foil protection, no significant change could be detected in terms of microstructure, but the fibers started to show ductile behavior. [11] The average carbon concentration in the W fiber was difficult to analysis, as to separate the fiber and the matrix after sintering was quite challenging. The overall carbon content in the W f /W was neglectable based on a combustion test.…”

Section: Composite Manufacturingmentioning

confidence: 99%

“…To overcome this drawback, W fiberreinforced W (W f /W) composites have been developed. [5][6][7][8][9] Relying on an extrinsic toughening principle, even in the brittle regime, this material allows for a certain tolerance toward cracking and damage in general in comparison to conventional W. [5,[10][11][12][13][14] In general, similar to the ceramic fiber-reinforced composites, a relatively weak interface between the fiber and the matrix is considered to be beneficial to achieve the so-called pseudoductility. [10,13,[15][16][17] In previous studies, the W f /W material is mainly produced by chemical vapor deposition (CVD) process.…”

Section: Introductionmentioning

confidence: 99%

“…a process using field-assisted sintering technology (FAST) to produce W f /W composite has been established. [5,10,11,20] As it is technically difficult to introduce aligned long fibers into the bulk material like the CVD process, short fibers with random distribution are used to realize the reinforcement in the FAST process.…”

Section: Introductionmentioning

confidence: 99%

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Fiber Volume Fraction Influence on Randomly Distributed Short Fiber Tungsten Fiber‐Reinforced Tungsten Composites

et al. 2020

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For future fusion reactors, tungsten (W) is currently the main candidate for the application as plasma‐facing material due to its several advanced properties. To overcome the brittleness of W, randomly distributed short W fiber‐reinforced W (Wf/W) composites have been developed using field‐assisted sintering technology (FAST). Herein, Wf/W materials with different fiber volume fraction (20–60%) are manufactured by FAST process to study the fiber volume fraction influence on the composite properties. Wf/W with ductile fibers and brittle fibers is produced using different tool setups during the production. Three‐point bending tests on prenotched samples, 4‐point bending tests, and tensile tests have been performed to determine the fracture behavior and flexural/tensile strength of the material. Wf/W materials with 30–40% fiber volume fraction exhibit a promising pseudoductile behavior, similar to fiber‐reinforced ceramic composites. However, Wf/W with 20% and >50% fiber volume fraction shows only a limited extrinsic toughening effect. In terms of flexural strength, with increasing fiber volume fraction, the tensile/flexural strength does not show a clear increasing tendency, or even lightly decreases.

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Fusion Materials Development at Forschungszentrum Jülich

Coenen

2020

Adv Eng Mater

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Material issues pose a significant challenge for the design of future fusion reactors. From a historic point of view, the material mix used for the first wall of a fusion reactor has continually evolved, from original steel vessels to carbon and other low-Z materials such as beryllium to tungsten as the primary candidate for a reactor's first wall armor and divertor material. For materials considered for fusion applications, a highly integrated approach is necessary. Resilience against neutron damage, good power exhaust, and oxidation resistance during accidental air ingress are design relevant issues while deciding on new materials or improving upon baseline materials. Neutron-induced effects, e.g., transmutation adding to embrittlement, retention, and changes to thermomechanical properties, are crucial to material performance. In this contribution, the recent progress (2013-2019) in fusion materials development for current and future fusion devices, at Forschungszentrum Jülich GmbH, with activities focussing on advanced materials and their characterization is given. It is a continuation and extension of the work given by Coenen et al.

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Improved pseudo-ductile behavior of powder metallurgical tungsten short fiber-reinforced tungsten (W/W)

Cited by 43 publications

References 26 publications

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites

Fiber Volume Fraction Influence on Randomly Distributed Short Fiber Tungsten Fiber‐Reinforced Tungsten Composites

Fusion Materials Development at Forschungszentrum Jülich

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