Thermonuclear fusion produced when two atomic nuclei of light elements combine to produce heavier elements, which give off a huge quantity of energy promises to be a possible solution to the current energy crisis.

In order that this reaction can occur, it is necessary to supply an enormous amount of energy, so temperatures of many millions of degrees can be reached, allowing nuclei to come close enough to overcome their natural repulsion and become condensed in a plasma state.

“This plasma, which reaches temperatures near that of the stars, around 100m degrees, does nottouch the walls of the reactors because they would melt,” explained one of the project researchers, Dr Vanessa de Castro, (right) from the UC3M Physics Department.

In order to confine the plasma within the reactor it is held by magnetic fields. “Even so the walls must resist some very high temperatures as well as the effects of the irradiation from the neutrons from the reaction, for which we have to produce new materials that can withstand these extreme conditions,” she remarked.

The ITER project (under construction) and successor, DEMO (scheduled for 2035) propose development of fusion reactors that are economically viable. This work depends on, among other things, the development of these new structural materials capable of withstanding damage by irradiation and elevated temperatures resulting from the fusion reaction.

The scientific community has begun to develop new reduced - activation material for use in these reactors, but it is still unknown if some of them will be viable under such hostile conditions. One of the most important candidates is oxide dispersion-strengthened, reduced-activation ferrite steel, called ODS steel. 



The mechanic behaviour of the ODS steels depends enormously on their microstructure, which until now has not been rigorously controlled. Until recently, studies on the microstructure of these steels have been on the micrometric scale. The deca-nanometric scale is more relevant to understanding the phenomena that occur under irradiation.

“We are now using our knowledge in nuclear structural materials and advanced techniques of nano analysis to characterise diverse new generation ODS steels on the nano-metric scale,” note the researchers, who have added nano-metric particles to these steels (between 1 and 50 nm), which help to improve the mechanical properties and increase their resistance.

The results of the research have been recently published in a special number of the journal Materials Science and Technology dedicated to the atomic scale characterisation of steels.

Characterisation of these materials is carried out using transmission electron microscope (TEM), which allows particles to be seen when they are added to the material. Studies can be undertaken to optimise the  distribution of the particles,  check its chemical composition is good, or  whether by changing it, better material is obtained or if any interaction of these particles with defects produces improved material.

“We extract the information that allows us to explain why material behaves in one way or another, because the fact that it has bad mechanical properties could be related to the particles not being well-distributed”, ESTRUMAT’s Professor de Castro, points out.

The objective of this Advanced Structural Materials consortium, composed of five research groups from four universities and a Madrid Region research institute, is to provide a framework of scientific-technological activity in the area of advanced materials structures for applications in engineering.



This research, funded by the Ministry of Science and Innovation, is focused on the study of oxide nano particles which are present in these steels, and the damage caused by radiation of these materials. The analyses carried out up to now show, for example, that the particles have a core-shell type structure consistent in an yttrium(Y) -rich nucleus surrounded by a chrome (Cr)-enriched area.