Afsaneh Rabiei checks on metallic foam created in her lab. (Credit: Rabiei/North Carolina State University) The word foam doesn't necessarily convey strength, but seeing a bullet explode upon impact with composite metal foam certainly does. Researchers at North Carolina State University created a bubble-filled metal composite that combines the strength of steel with the airiness and heat-resistant properties of foam. In tests with armor-piercing bullets, a one-inch layer of the material stopped the projectile in its tracks while allowing only an 8-millimeter indentation on the other side. Afsaneh Rabiei, a professor of mechanical and aerospace engineering at North Carolina State University, claims her version of metallic foam is the strongest yet.
Foams are made mostly of air pockets — that's what makes them so light. They derive their strength from the composition and structure of the material that surrounds the air pockets, a steel alloy in this case. Rabiei has ...
