Interview: How additive manufacturing can make fusion components more resilient
03.06.2026
Plasma-loaded components are among the most demanding parts of future fusion power plants: they have to withstand extreme thermal, mechanical and radiation-related stresses. Dr. Georg Schlick from the Fraunhofer Institute for Casting, Composite and Processing Technology IGCV in Augsburg explains the role that additive manufacturing, tungsten-copper structures and multi-material concepts can play in this.
Dr. Schlick, when we look at the components inside a fusion power plant: What conditions do these components actually have to deal with?
In many areas, the stresses in fusion plants exceed what is known from conventional energy technology applications. Heat loads of up to 20 MW/m² are specified for internal wall and divertor areas, and even higher in short-term load cases. These heat flows lead to pronounced temperature gradients and thus to considerable thermally induced stresses. Added to this are plasma-wall interactions, which can lead to material erosion and surface changes.
Heat and mechanical stresses are one thing; we are already familiar with them from other high-tech areas such as aerospace. What additional challenges does fusion pose for the materials used?
An additional special feature of nuclear fusion is the intense neutron exposure. This influences the microstructure of the materials used, changes mechanical properties and limits the choice of possible material systems. At the same time, materials must be selected in such a way that undesirable radiation-induced activation effects and the transmutation of elements are kept to a minimum. This results in a narrow material technology requirement profile that must take into account high temperature properties as well as radiation resistance and low activatability. Against this background, tungsten has largely established itself as a central material for plasma-loaded areas due to its high melting temperature and low sputtering rate.
This means that tungsten is set on the plasma side, but is also considered difficult to process. How can such components still be manufactured efficiently and integrated into functioning components?
Yes, the processing of tungsten is challenging. Conventional process routes are predominantly based on powder metallurgical processes, in particular sintering and downstream forming steps. Against this background, the Fraunhofer IGCV has been pursuing approaches that allow complex tungsten structures to be additively manufactured and specifically coupled with copper-based heat sinks. The aim is to achieve a functional transition between the plasma-side surface and the heat-dissipating structure. This is particularly relevant because tungsten and copper differ significantly in terms of their thermal expansion and direct connections are only able to withstand cyclic thermal loads to a limited extent.
How can this transition between the very different materials be solved constructively?
One research focus was on the additive production of lattice-like intermediate structures made of tungsten using laser powder bed fusion. In subsequent steps, these were infiltrated with copper to produce composite systems with improved thermomechanical behavior. In high heat flux tests, corresponding test specimens were examined that combine rolled tungsten elements with additively manufactured, copper-infiltrated transition structures. The results show that such architectures have the potential to improve the control of thermal loads.
So far, that sounds like a combination of several production steps. Is the development also moving in the direction of direct material combinations in the construction process?
Beyond the combination of separately manufactured material areas, additive manufacturing opens up the prospect of processing different materials directly within a manufacturing process in a locally defined manner. In cooperation with industrial partners, process approaches have been investigated in which different metallic powders are successively introduced and selectively melted within a single layer.
What is already possible today with such multi-material structures and where does the need for research begin?
This approach offers the possibility of building three-dimensional multi-material structures with high functional integration and substituting conventional multi-stage joining or infiltration processes. Complex metallic material combinations of copper and up to two other materials (e.g. steel or nickel-based alloys) have already been realized. The transfer to the tungsten-copper system, which is particularly relevant for fusion applications, is the subject of ongoing research work. Due to the very different thermophysical and process-related properties of the two materials, there is still a considerable need for development in this area. Nevertheless, this approach in particular opens up great potential for future component architectures designed to meet load requirements.
In addition to the combination of materials, it is also important to dissipate heat reliably. What does this mean for the geometry of such components?
In addition to the directly plasma-loaded high-load areas, complex cooling structures are also of central importance for future fusion systems. Copper-based heat sinks and heat sinks in particular must safely dissipate high thermal loads and at the same time be provided in a geometrically highly integrated form. Additive manufacturing processes offer considerable degrees of freedom for this, as they enable the production of internal channel structures and functionally integrated geometries that are difficult or impossible to realize with conventional manufacturing processes.
When such complex copper structures are additively manufactured: What needs to be demonstrated and mastered afterwards?
As part of the work, large-volume and complex copper structures were also developed, such as those that are important in the Wendelstein 7-X environment. While such components have so far often been constructed and joined from a large number of individual parts, additive manufacturing allows the realization of largely monolithic components. However, this poses specific challenges. These include, in particular, the achievable helium leak tightness, the complete removal of unmelted powder residues from internal channels, suitable post-treatment strategies and in-process quality assurance.
In your opinion, what are the next steps that need to be taken to turn such approaches into reliable process chains?
For future industrial use, it will be crucial to transfer the developed approaches into robust, scalable and economically viable process chains. In addition to the further qualification of additively manufactured multi-material systems in terms of materials and processes, validation under realistic thermal and mechanical load conditions will play a key role. Additive manufacturing can thus become a key technology for the realization of high-performance fusion components.
