Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

Self-passivating, so-called smart alloys are under development for a future fusion power plant. These alloys containing tungsten, chromium and yttrium must possess an acceptable plasma performance during a regular plasma operation of a power plant and demonstrate the suppression of non-desirable oxidation of tungsten in case of an accident. The up-scaling of the bulk smart alloys to the reactor-relevant sizes has begun and the first samples with a diameter of 50 mm and thickness of 5 mm became available. The samples feature high relative density of above 99% and good homogeneity. With production of bulk samples, the research program on joining the smart alloy to the structural material was initiated. In a present study, the novel titanium–zirconium–beryllium braze was applied successfully to join the smart alloy to the Rusfer-reduced-activation steel. The braze has survived at least a hundred of cyclic thermal excursions in the range of 300–600 °C without mechanical destruction.

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“…Presently, there is no filler alloy consisting of low-activation elements only. Nickel [28] or copper [29]-based alloys are frequently used.…”

Section: Methodsmentioning

confidence: 99%

Self-passivating smart tungsten alloys for DEMO: a progress in joining and upscale for a first wall mockup

et al. 2021

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“…Prado et al have been studying the use of Cu-20Ti wt.% powder brazing alloy for joining tungsten to Eurofer steel directly [14,[39][40][41][42][43]. The filler was fabricated by laminating a mixture of pure metallic powders or mechanically alloyed powders with an organic binder.…”

Section: The Latest Progress Made In Tungsten/steel Brazingmentioning

confidence: 99%

“…By means of pure powders at a brazing mode of 960 • C for 10 min, the shear strength of the joint was measured as 145 ± 4 MPa [39]. When mechanically alloyed powders are used, the value is significantly lower-93 ± 28 MPa [41]. At the same time, the microstructures of the seams are very close, but the difference in the amount and shape of the phases formed may be the reason for such a difference.…”

Section: The Latest Progress Made In Tungsten/steel 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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“…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%

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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Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

Cited by 38 publications

References 21 publications

Self-passivating smart tungsten alloys for DEMO: a progress in joining and upscale for a first wall mockup

Self-passivating smart tungsten alloys for DEMO: a progress in joining and upscale for a first wall mockup

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

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

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