After two decades of development, a new lightweight metallic material created by North Carolina State University engineering professor Afsaneh Rabiei and her Raleigh-based company Advanced Materials Manufacturing (AMM) has hit the industrial market.
Likening it to a metal bubble wrap, AMM their "composite metal foam" design can make almost any metal or alloy 100 times more energy absorbent, three times lighter, more radiation resistant and 7.5 times longer-lasting in extreme heat fires.
The company the product is "as strong as steel yet as lightweight as aluminum," adding that "a 100% steel composite metal foam bar will weigh the same as an equal-sized solid aluminum bar."
AMM further advertises that composite metal foams, or CMFs for short, require 70% less metal compared to solid blocks of material, making it less ecologically damaging and cheaper, particularly under President Trump's recent metal tariffs.
The material's strength, Rabiei explained, comes from its unique production, which can take two forms. The first method, casting, involves encasing hollow metal spheres in a molten form of that same metal. After cooling, they are left with a solid block of metal with many spherical air pockets inside.
The second method, powder metallurgy, is essentially the same, though instead surrounds those spheres in a pool of powdered metal which AMM melts solid.
Previous metal foam designs 鈥� what Rabiei calls "open cell foams" 鈥� were more porous than CMFs and more akin to airy metal sponges. CMFs, by contrast, are "closed cell foams," relying on the trapped air bubbles to resist compression and insulate heat.
The product's versatility has AMM marketing it to a variety of industries ranging from transportation and aerospace to sporting goods.
One use case Rabiei points to was the 2023 train derailment in East Palestine, Ohio, where hazardous material spilled out of cargo containers after a faulty wheel bearing . CMF's ability to resist puncture damage and high temperatures makes it well-suited for keeping hazardous materials in their containers, she says.
Rabiei also emphasized its utility in the defense sector, having found CMFs to perform as well as or better than their parent material when a .50 caliber bullet, from TNT or armor from a bullet.
"It's a sacrificing layer," she said. Like our bones, which are also porous, it absorbs impact to protect something precious 鈥� a brain or heart in a human body, and a whole person in a tank or car.
Rabiei began developing the design in 2003, working on it while teaching mechanical and aerospace engineering at N.C. State, a job she's held since 2000. Her ties to North Carolina and N.C. State are part of why she's so far despite offers from out of state.
"It's like my baby," she said. "I want to watch it grow."
