Designing metallic alloys to do more

Jagannathan Rajagopalan’s research has led to nine granted patents and new ways to design metallic alloys for applications in electronics, robotics and biomedical devices.

Because of this work, Rajagopalan, an associate professor of mechanical and aerospace engineering in the School for Engineering of Matter, Transport and Energy, part of the Ira A. Fulton Schools of Engineering at Arizona State University, has been elected as a 2026 National Academy of Inventors senior member.

He says the recognition came as a surprise. Partly because his work focuses less on building products and more on characterizing and tailoring the microstructure of materials, an area of study key to various modern technologies, including phones, cars, planes and biomedical devices. His research examines how materials’ microstructure can be manipulated to improve their properties and performance.

Rajagopalan points to his first patent as a turning point in his career.

To the naked eye, a piece of metal such as copper or a nickel-aluminum alloy may appear smooth and uniform. At smaller scales, however, it is made up of millions of sand-like crystal structures — known as grains — of different sizes, shapes and orientations. These crystals are the fundamental structural units of a metal alloy.

Within each grain, atoms are arranged in a repeating, three-dimensional pattern known as a lattice. The size, shape and orientation of the grains influence how a material behaves, including whether it bends, breaks, conducts electricity or resists heat.

But controlling how these grains form and are distributed within a material is not straightforward.

In his patent, Rajagopalan introduced a new approach to directly control the size, distribution and orientation of grains in thin films of metallic alloys, which are integral components of semiconductor chips, solar panels, TV screens, sunglasses and more. He says the approach opens doors to designing materials for specific uses rather than adapting existing ones.

“For example, we work on nickel-titanium films and being able to tailor their microstructure enables us to precisely control the temperatures at which they morph from one configuration to another and how much force they apply while doing so. This has major implications for soft robotics and biomedical devices,” he says. “These films, for example, can be used as microgrippers in minimally invasive surgery or coatings in stents that are used to open up arteries.”

Rajagopalan’s approach to controlling a material’s microstructure begins with an unconventional starting point: a metallic glass, an amorphous material in which atoms are arranged randomly rather than in an ordered, repeating structure.

By starting from a blank slate, he can decide where grains form within the material, controlling their size, shape and distribution for a specific application. One way Rajagopalan creates these films is by building the material layer by layer.

To make a nickel-titanium film using this method, he starts with separate cylindrical disks of nickel and titanium called sputtering targets, which are installed inside a magnetron sputtering system. He then introduces argon gas, which is ionized by an electric field. The argon ions bombard the nickel and titanium targets, ejecting atoms from them in the process.

These atoms travel through the sputtering chamber and are deposited on a substrate such as a silicon wafer. Since the atoms lose energy when they contact the substrate, they remain frozen in place at the random locations where they land, instead of forming an ordered lattice. This creates an amorphous nickel-titanium layer.

Rajagopalan then deposits an extremely thin layer of a pure metal, such as chromium or tungsten, which forms tiny crystalline seeds on the surface of the amorphous nickel-titanium layer. He repeats the process, depositing another amorphous nickel-titanium layer with seed layers, many times to achieve a specific goal. The crystalline seeds serve as templates that determine where grains will begin to form in the nickel-titanium layers when the material is later heated.

“As the temperature increases, nickel and titanium atoms gain enough energy to move and begin organizing around these seeds and grow into grains,” Rajagopalan says. “By controlling the location and distribution of these seeds during deposition, we can effectively dictate where new grains form throughout the material with a level of precision not possible using traditional methods.”

This innovative approach, along with others, is central to Rajagopalan’s selection as a 2026 National Academy of Inventors senior member.

By becoming an NAI senior member, Rajagopalan joins a group of renowned researchers who translate fundamental discoveries into innovations with significant potential for real-world impact.

He joins 945 researchers representing more than 100 institutions worldwide, collectively holding nearly 11,000 U.S. patents.

The recognition highlights not just the number of patents he holds, but also the way his work connects the fundamental understanding of materials’ microstructure with practical applications. For the past 14 years at ASU, Rajagopalan has been developing tools that other researchers and industries can build on, enabling new possibilities in fields ranging from medicine to electronics.

Looking ahead, Rajagopalan is exploring ways to develop metallic glass films that remain amorphous even at high temperatures, with a particular interest in computing applications.

For example, in semiconductor devices, different materials — such as copper and silicon — are often layered together. Over time and under high temperatures, atoms from one layer can begin to diffuse into another, degrading chip performance or causing failure.

“A stable metallic glass layer can act as a barrier between them,” he says. “These structures could have many other applications, including the ability to withstand stress and impact at high temperatures."

Terry Alford, the associate director of the School for Engineering of Matter, Transport and Energy, who nominated Rajagopalan for the honor, congratulates him and highlights the potential impact of his work.

“I am excited that Jagan was selected as an NAI senior member,” Alford says. “His approach to controlling materials’ microstructure is innovative, and his patents are proof of the immense potential impact of his work. I look forward to the contributions he will make to his field and society as a NAI senior member.”