As Managing Director of the Max Planck Institute for Iron Research, Dierk Raabe is on the lookout for materials with intelligent properties.

^{(Interview: Judy Born)}

What does the Institute do?

We conduct basic research, like all the institutes belonging to the Max Planck Society. In our case, the research involves investigating metallic materials with a focus on iron and iron-related materials.

What distinguishes the Max Planck Institute for Iron Research from others?

We cooperate with the industry to a great extent. And our connection to it is growing because we also receive basic funding from the steel industry for our projects.

As Managing Director, do you conduct research yourself?

Yes, I do. In this position one has to take care to be more than just a manager or an administrator. Research has to be sustainable, meaning that it takes perseverance, among other things. Work on a single development can drag on for decades. I can’t be everywhere at once, but I do still play a very active part in my own research programs.

What’s the last thing you researched?

Correlating atom probe tomography. This approach is based on the idea that in principle you can recognize every single atom as a chemical species and assign it a position in the material. If, for example, there are hydrogen atoms in a high-strength material, this can lead to failures that may have catastrophic consequences. Think about the undercarriage of an aircraft, for example. Atom probe tomography makes it possible to dismantle metals atom by atom and determine their behavior. Even minor changes to the atomic contents of a given material can sometimes lead to massive changes in the material.

You are also researching what are known as ‘self-healing’ steels. What are those?

This approach is based on observations of the human body. When we get injured, our body is usually able to heal itself. Take, for example, a broken bone or a laceration on the skin. Our body recognizes that the tension between the cells has changed at the site of the injury and it activates mechanisms whose purpose is to put things back in order.

And can the same process be translated to inorganic materials?

Absolutely! The advantage is that atoms don’t stay in one place, but wander to and fro. Their mobility and binding energy vary depending on their environment, which can be influenced by increasing the temperature, for example. We are currently conducting tests on steels and nickel materials that were designed for high temperatures and will be used in the making of turbines for power generation. In practice this means that when I introduce specific, sufficiently flexible atoms into a material and the turbine sustains a small tear or a pore, then these atoms will wander in larger numbers to the site of the defect and seal it up under ideal circumstances, provided the defect is small enough.

So steel is a clever material...

There is a term for this: smart materials. It refers to materials whose purpose changes when their boundary conditions change. For example, there are magnesium alloys that disintegrate and dissolve inside the body. Imagine an implant that only needs to be in the body temporarily, for example, screws that help a broken bone mend. If the wound grows together, the doctor will have to operate to remove the screws. But there’s no need for an operation if they dissolve on their own.

... and does steel still have a future?

Of course! There is enormous demand for steel worldwide. High-rises and plants of all shapes and sizes, bridges, and many more things would be unthinkable without steel. The biggest challenge for the steel industry in Europe is lightweight construction, because a large percentage of our sales come from automobile production. The construction industry is especially interested in intelligent materials. I’m thinking of communicating steels, which use acoustic properties or changes in resistance to inform engineers immediately when renovation is needed. Damage to bridges and high-rises can be recognized and repaired at an early stage. And in the future we will be dealing with smart buildings, too.