Joining tungsten with steel for DEMO: Simultaneous brazing by Cu-Ti amorphous foils and heat treatment

Bachurina, Diana; Сучков, А. Н.; Gurova, Julia; Savelyev, Maxim; Джумаев, П. С.; Kozlov, Ilya; Светогоров, Р. Д.; Leont’eva-Smirnova, M. V.; Sevryukov, O. N.

doi:10.1016/j.fusengdes.2020.112099

Cited by 14 publications

(8 citation statements)

References 23 publications

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“…Samples were inserted into the ampoule and a thermocouple was as close as the samples. Previously we carried out thermocycling with cooling down by water [8,11] that was used to make express comparison of joints, but in this work we decided to carry out thermocycling closer to operating conditions. RAFM steel working temperature is limited to 550 • C, so we decided to heat up the joint to 600 • C, as the joints' temperature can be higher.…”

Section: Methodsmentioning

confidence: 99%

“…Usually, intermediate layers are used to suppress a mismatch of CTE [9]. In DEMO, in order to relieve these stresses, it is proposed to use Nb [10], V [11], Ti [12], Cu [13], and Ta [14].…”

Section: Introductionmentioning

confidence: 99%

“…However, until now no fully reduced activation brazing alloy has been used, or the strength of the joint was low [21]. Instead, scientists use nickel [17,22,23] or copper [11,[24][25][26] brazing alloys, although these materials do not fully satisfy the requirement of reduced activation. To solve this problem, we are attempting to use a fully reduced activation composition, 48Ti-48Zr-4Be wt.%.…”

Section: Introductionmentioning

confidence: 99%

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Brazing Tungsten/Tantalum/RAFM Steel Joint for DEMO by Fully Reduced Activation Brazing Alloy 48Ti-48Zr-4Be

Bachurina

Сучков

Gurova

et al. 2021

Metals

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To create a DEMO reactor, it is necessary to develop high-quality technology to join tungsten with reduced-activation ferritic-martensitic (RAFM) steel (Rusfer, Eurofer, CLF-1, etc.). Difficulties arise in their direct connection due to the large difference in the coefficient of thermal expansion (CTE). To suppress the difference of CTE, intermediate interlayers are usually used, such as vanadium or tantalum, and brazing is a prospective technology to conduct the joining. The vast majority of works represent copper- or nickel-based brazing alloys, but their applicability is under significant discussion due to their activation properties. That is why, in this work, fully reduced activation 48Ti-48Zr-4Be wt.% brazing alloy was used. The following joint was made: Rusfer steel/48Ti-48Zr-4Be/Ta/48Ti-48Zr-4Be/W. The brazing was successfully carried out under a mode providing thermal heat treatment of Rusfer. Through EDS and EBSD analysis, the microstructure of the joint was determined. Shear strength of the as-joined composition was measured as 127 ± 20 MPa. The joint endured 200 thermocycles in the temperature range between 300–600 °C, but the fillet regions degraded.

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Section: Methodsmentioning

confidence: 99%

“…Usually, intermediate layers are used to suppress a mismatch of CTE [9]. In DEMO, in order to relieve these stresses, it is proposed to use Nb [10], V [11], Ti [12], Cu [13], and Ta [14].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Brazing Tungsten/Tantalum/RAFM Steel Joint for DEMO by Fully Reduced Activation Brazing Alloy 48Ti-48Zr-4Be

Bachurina

Сучков

Gurova

et al. 2021

Metals

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“…Our scientific group investigated Cu-based brazing alloys that rapidly solidified into foil. Cu-28/50Ti, Cu-12/20Sn, and Cu-12/25Ge, wt.% [12,26,33,38], and a vanadium interlayer were used to overcome the mismatch in CTE between tungsten and the Rusfer steel. In all cases, Cu-50Ti brazing alloy was used to join W with V, because Cu, Sn, and Ge do not dissolve in W, while Ti has a good solubility in W. Hence, to join V to Rusfer, other brazing alloys were investigated.…”

Section: The Latest Progress Made In Tungsten/steel Brazingmentioning

confidence: 99%

“…Thus, Fe-based and Ti-based brazing alloys with added melting-point depressants (B, Be, Si) could prospectively aid in the joining of tungsten to RAFM steel. Summarizing the review above, only a few joints can endure the stresses calculated in Section 2.3: [15,18,19,33,38,46]. The highest strength relates to the joints brazed by pure copper.…”

Section: Brazingmentioning

confidence: 99%

Overview of the Mechanical Properties of Tungsten/Steel Brazed Joints for the DEMO Fusion Reactor

Bachurina

Vorkel

Сучков

et al. 2021

Metals

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A Demonstration (DEMO) thermonuclear reactor is the next step after the International Thermonuclear Experimental Reactor (ITER). Designs for a DEMO divertor and the First Wall require the joining of tungsten to steel; this is a difficult task, however, because of the metals’ physical properties and necessary operating conditions. Brazing is a prospective technology that could be used to solve this problem. This work examines a state-of-the-art solution to the problem of joining tungsten to steel by brazing, in order to summarize best practices, identify shortcomings, and clarify mechanical property requirements. Here, we outline the ways in which brazing technology can be developed to join tungsten to steel for use in a DEMO application.

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Wettability and microstructural evolution of copper filler in W and EUROFER brazed joints

Izaguirre,

de Prado,

Sánchez

et al. 2024

Int J Adv Manuf Technol

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In terms of wettability, active systems are characterized by a reduction in interfacial energy as the time at specific conditions is increased. This article aims to investigate the evolution of wettability and microstructure, which undergoes a critical transformation at temperatures and dwell times near brazing conditions due to their significant impact on resultant mechanical properties. The objective is to enhance wettability and prevent the formation of different phases that can occur rapidly within the brazing window conditions. Up to 1105 °C, complete fusion of the filler does not occur. However, once it happens, the expansion of the copper filler in EUROFER increases up to 400%, and the contact angle reduces from 100° to 10°, indicating an active wetting behavior. On the other hand, when copper is used with tungsten, an inert behavior is observed, maintaining the contact angle around 70°. Brazed joints carried out under the most promising wetting conditions demonstrated that at 1110 °C-1 min, various phenomena began to occur. This includes solid-state diffusion of copper in the EUROFER, following the austenitic grain boundaries, and partial dissolution of Fe in the copper braze. Increasing the brazing time from 2 to 5 min achieved high interfacial adhesion properties and controlled the diffusion layer and Fe-rich band formed at the W-braze interface, resulting in the best mechanical results (295 MPa).

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Joining tungsten with steel for DEMO: Simultaneous brazing by Cu-Ti amorphous foils and heat treatment

Cited by 14 publications

References 23 publications

Brazing Tungsten/Tantalum/RAFM Steel Joint for DEMO by Fully Reduced Activation Brazing Alloy 48Ti-48Zr-4Be

Brazing Tungsten/Tantalum/RAFM Steel Joint for DEMO by Fully Reduced Activation Brazing Alloy 48Ti-48Zr-4Be

Overview of the Mechanical Properties of Tungsten/Steel Brazed Joints for the DEMO Fusion Reactor

Wettability and microstructural evolution of copper filler in W and EUROFER brazed joints

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