C. Cem Tasan

In Cem Tasan’s laboratory at MIT, research often stems from an industry-related engineering problem. For example, steel manufacturers often look to simultaneously increase the strength, ductility, or formability of their metals. Strength allows your components to sustain high loads while formability enables you to make more complex shapes. But high strength usually results in degraded formability. Tasan and his team collaborate with industry partners to understand how different microstructures behave, which, among other things, allows them to provide guidelines to improve strength and ductility at the same time. “We create setups for microscopes to imitate engineering problems faced by industry,” he says. “But we dig deeper into the fundamentals, which allows us to provide new answers. Often, industry is not in a position to dive as deep as we can in the lab.”

Regarding industry-academia collaborations, Tasan notes that it is not always straightforward for industry and academia to connect, but, he says, “At MIT we are lucky to have the Industrial Liaison Program (MIT ILP). In my experience, MIT ILP has been crucial when it comes to bringing industry and its challenges to our campus, which allows my group to propose novel solutions.”

Tasan notes that his research is also often driven by sheer curiosity. Tasan lab’s in-situ characterization capabilities allow them to make samples of nearly any metal that interests them and put it in a scanning electron microscope to see how its microstructure evolves in real-time. “Very often, we’re inspired and surprised by what unfolds,” he says. For example, Tasan and his group have witnessed a specific two-step phase transformation in one of the designed alloys they were testing. Seeing a new sequential transformation mechanism like this often opens the door to new ideas related to application.

Tasan tempers expectations with a dose of reality: “Of course, we have to be honest; application solutions are not always easy: there are many requirements to be able to use a new metal in a new application. But coming up with new design concepts based on curiosity-driven research is the first step on the journey towards new solutions to engineering challenges.”

Before joining the faculty at MIT, Tasan studied metallurgical engineering at the Middle East Technical University in Ankara. From there, he moved to the Netherlands, where he earned his PhD in the mechanics of materials at Eindhoven University of Technology. He went on to complete his postdoctoral research in Germany at the Max Planck Institute for Iron Research.

Metals are special because the structure-property relationships at the core of material science can be most easily studied in metals with the tools available to us. I’m fascinated and inspired by those connections and the surprises hidden in the microstructures of metals. 

One aspect of Tasan’s work involves developing new methods to demonstrate the structure of metals as they evolve under different boundary conditions (e.g., stress, temperature). Recently, he and his team of researchers developed a method (“a miniaturized setup, really,” he says) that allowed them to electrochemically charge hydrogen to metals while studying their structure in a scanning electron microscope.

“Using our setup in the electron microscope as you charge hydrogen to a metal—a steel or a titanium alloy, for instance—you can see the microstructural changes that take place as hydrogen goes into the microstructure,” Tasan explains. Despite being a small, light atom, hydrogen can significantly impact the structure of metals. “If you were to try to do this type of characterization of hydrogen effects in a before-and-after fashion, you wouldn't be able to understand many of these changes. Being able to do this in the electron microscope, we can actually see the changes as they take place.”

Novel techniques like the in-- hydrogen charging setup, allow Tasan to lay bare the underlying physics that govern metallurgic properties. “In titanium alloys, if hydrogen enters the microstructure, it typically ends up with a formation of hydrides,” he explains. But hydrides cause embrittlement, which is undesired. “Now, if you carry out the type of tests we do with the setup that we designed, we can see the differences in hydride formation in different microstructural constitutes, which gives you insights about hydrogen diffusion pathways, where hydrogen is collected or trapped, and how hydrides eventually form.” This type of key insight into the physical mechanisms of metals derived from in-situ methods developed in Tasan’s lab enables the design of new damage-resistant alloys.

Metallurgy has existed for thousands of years, but even today, the design concepts for metals are largely derived from trial-and-error processes. However, the Tasan group, armed with new insights into the mechanisms of metals (thanks to their novel in-situ methods) is opening the door to novel design concepts for materials and material systems. For instance, Tasan and his collaborators are simultaneously designing new hydrogen barrier coatings, surface roughening treatments, and hydrogen trapping microstructures—all to reduce the likelihood of hydrogen embrittlement in key metallic materials.

Given the fact that we are confronting the engineering challenges associated with a transition towards a hydrogen-based economy, transporting hydrogen, for example, the scientific findings and technologies designed in Tasan’s lab might provide a solution that would allow us to use existing natural gas pipelines to safely transport hydrogen despite the threat of embrittlement.

Looking to the future, Tasan says, “There isn't a week that goes by where we don't hear about a new metals challenge or a problem that we can use our techniques to dig deeper. Thus, several activities are currently being initiated in my lab, both digging deeper into the science but also coming up with technological solutions, engineering solutions. The future is bright!”