High temperature oxidation behavior of W–Cr–Nb Alloys in the Temperature Range of 800–1200°C

Telu, Suresh; Mitra, Rahul; Pabi, S.K.

doi:10.1016/j.ijrmhm.2012.12.008

Cited by 23 publications

(5 citation statements)

References 16 publications

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“…Several fabrication strategies have been studied so far. Most of the techniques used in the production of bulk smart alloys include mechanical alloying (MA) of the elemental powders of tungsten and alloying elements [235][236][237][238][239][240][241][242][243], followed by either by sintering [238] or by hot isostatic pressing (HIP) [235][236][237].…”

Section: Bulk Smart Alloy Systemsmentioning

confidence: 99%

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Development of advanced high heat flux and plasma-facing materials

et al. 2017

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Plasma-facing materials and components in a fusion reactor are the interface between the plasma and the material part. The operational conditions in this environment are probably the most challenging parameters for any material: high power loads and large particle and neutron fluxes are simultaneously impinging at their surfaces. To realize fusion in a tokamak or stellarator reactor, given the proven geometries and technological solutions, requires an improvement of the thermo-mechanical capabilities of currently available materials. In its first part this article describes the requirements and needs for new, advanced materials for the plasma-facing components. Starting points are capabilities and limitations of tungsten-based alloys and structurally stabilized materials. Furthermore, material requirements from the fusion-specific loading scenarios of a divertor in a water-cooled configuration are described, defining directions for the material development. Finally, safety requirements for a fusion reactor with its specific accident scenarios and their potential environmental impact lead to the definition of inherently passive materials, avoiding release of radioactive material through intrinsic material properties. The second part of this article demonstrates current material development lines answering the fusion-specific requirements for high heat flux materials. New composite materials, in particular fiber-reinforced and laminated structures, as well as mechanically alloyed tungsten materials, allow the extension of the thermo-mechanical operation space towards regions of extreme steady-state and transient loads. Self-passivating

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Section: Bulk Smart Alloy Systemsmentioning

confidence: 99%

“…Bulk W-Cr-Y O 2 3 alloys were manufactured by mechanical alloying of W, Cr and Y O 2 3 powders according to [239][240][241][242][243]. The MA resulted in ultra-fine grain alloyed powders with the grain size of 30-50 nm.…”

Section: Bulk Smart Alloy Systemsmentioning

confidence: 99%

Development of advanced high heat flux and plasma-facing materials

et al. 2017

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“…In metallographic cross section two layers are observed, in accordance with ref. [2][3][4][9][10][11][12]: an inner (dark contrast) Cr 2 O 3 layer and an outer Cr 2 WO 6 mixed-oxide layer, each about 50m thick. Both appear continuous and adherent.…”

Section: Microstructurementioning

confidence: 99%

“…However, they are severely sensitive to oxidation at elevated temperatures. Muramatsu and Takedu [1], Diliberto et al [2] and Telu et al [3,4] studied W-Cr and W-Cr-Nb alloys, respectively. They found that W-30wt% Cr (equivalent to W-50at% Cr) possess better oxidation resistance than other alloys.…”

Section: Introductionmentioning

confidence: 99%

On the Mechanism of Oxidation Resistance of W-Cr-Pd Alloys

Kafri

Makonovitsky

Shneck

2018

DDF

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While studying activation sintering of tungsten, Evans [5] and Ito and Furusawa [6] revealed that W-Cr-Pd alloys exhibit unexpected oxidation resistance at elevated temperatures. The role of palladium in stimulating oxidation resistance in W-Cr alloys is the main aim of the present contribution. As previously observed, at 800 °C these alloys form a relatively dense protective scale that consists of an inner layer of Cr2O3, an intermediate layer of Cr2WO6 and an external layer of WO3. At 1200 °C only Cr2WO6 layer is found, since the Cr2O3 and WO3 evaporate. To determine the role of paladium, W and W-Pd alloys were coated with Cr layers and undergone diffusion experiments. An extraordinary affinity between the Cr and Pd was revealed, manifested by extremely fast inward diffusion of Cr along grain boundaries. In a second experiment the dissolution of Cr into W grains at 1300°C was followed and found to take place preferentially along grain boundaries. These observations assess that the Pd segregated at grain boundaries provides fast diffusion channels for Cr to the free surface and it imparts the significant improvement of the oxidation resistance of W alloys, as suggested by Lee and Simkovitz [10-12].

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“…With these considerations in mind, the list of acceptable alloying elements in tungsten is reduced to only a few, including Ta, V, Cr, Ti, Si [14][15][16][17][18][19]. Among these possible alloying elements, Cr should be specifically mentioned for its possible contribution to the improvement of tungsten oxidation resistance [20][21][22][23]. It is indeed well-known that chromium has a natural tendency to form a thin protective oxide layer that passivates the material, which is the basic principle of its use in stainless steel.…”

Section: Introductionmentioning

confidence: 99%

SHS Synthesis, SPS Densification and Mechanical Properties of Nanometric Tungsten

Dine

Bernard

Herlin

et al. 2021

Metals

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Recent studies have shown that low grain sizes are favorable to improve ductility and machinability in tungsten, as well as a resistance to ablation and spallation, which are key properties for the use of this material in a thermonuclear fusion environment (Tokamaks such as ITER). However, as one of the possible incidents during Tokamak operation is the leakage of air or water from the cooling system inside the chamber, resulting in the so-called loss of vacuum accident (LOVA), extensive oxidation may arise on tungsten components, and the use of an alloy with improved oxidation resistance is therefore highly desirable. As current production routes are not suitable for the fabrication of bulk nanostructured tungsten or tungsten alloys samples, we have proposed a new methodology based on powder metallurgy, including the powder synthesis, the densification procedure, and preliminary mechanical testing, which was successfully applied to pure tungsten. A similar study is hereby presented on tungsten-chromium alloys with up to 6 wt.% Cr. Results show that full tungsten densification may be obtained by SPS at a temperature lower than 1600 °C. The resulting morphology strongly depends on the amount of the alloying element, presenting a possible second phase of chromium oxide, but always keeps a partial nanostructure inherited from the synthesized powders. Such microstructure had previously been identified as being favorable to the use of these materials in fusion environments and for improved mechanical properties, including hardness, yield strength and ductility, all of which is confirmed by the present study.

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High temperature oxidation behavior of W–Cr–Nb Alloys in the Temperature Range of 800–1200°C

Cited by 23 publications

References 16 publications

Development of advanced high heat flux and plasma-facing materials

Development of advanced high heat flux and plasma-facing materials

On the Mechanism of Oxidation Resistance of W-Cr-Pd Alloys

SHS Synthesis, SPS Densification and Mechanical Properties of Nanometric Tungsten

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