P.W.M. Peters (Sp), D. Muchilo, J. Hemptenmacher, H. Schurmann, German Aerospace Center (DLR),
Cologne (Germany)
The divertor in the fusion reactor is a component, which is extremely loaded especially in terms of heat flux. In
experimental fusion reactors these components have to conduct a heat flux of 15-20MW/m2. For the
experimental fusion reactor ITER the CuCr1Zr-alloy was selected from the available copper alloys as a heat sink
material for the divertor. The maximum service temperature of this alloy is limited to about 450°C as a result of
the influence of overaging taking place at high temperatures and long periods of time.
For future fusion power reactors new heat sink materials with improved mechanical properties and higher
temperature capabilities are required. One of the possibilities to improve the mechanical properties and the
temperature capabilities of the CuCr1Zr alloy is to reinforce the alloy with high strength fibres or wires. In the
scheme of the European integrated project “ExtreMat” DLR develops SiC-fibre and W-wire reinforced CuCr1Zr.
Two types of SiC-fibres are used: the SCS-6-fibre of Specialty Materials, USA and the SiC-fibre SM-1240 produced
by TISICS Sigma, England. The first fibre has a protection coating consisting mainly of carbon, whereas the
protection coating of SM-1240 is a double layer with a carbon- and TiB-layer. Composite materials are produced
making use of SiC-fibres (or W-wires), which are coated with the alloy in a magnetron sputter device. Coated
fibres (or wires) are stacked in a preform and the preform is sealed by vacuum welding. In a final step the
material is consolidated by hot isostatic pressing.
The work to be presented deals with the optimization of the interfaces. These optimization processes are the
application of additional interfacial layers on the fibre to improve fibre/matrix bonding and additional thermal
treatments of the processed materials. The analyses of the different interfaces are performed making use of the
EDX-detector attached to the scanning- and the transmission-electron-microscope. The Cr-content is enriched on
the fibre/matrix interface and influences most likely the fibre/matrix bonding. An evaluation of the mechanical
properties of the interface is realized with the aid of push-out experiments. A comparison is made with the
fibre/matrix interface properties for composites produced with a pure copper matrix.