Non-toxic shot-stopper

An engineering professor at the University of California, San Diego has described in the March issue of JOM (the Journal of the Minerals, Metals and Materials Society) the unique properties of a new type of metallic laminate.

According to Kenneth S. Vecchio, author of the paper and a professor of mechanical and aerospace engineering in UCSD's Jacobs School of Engineering, the material can serve as armour and as a replacement for beryllium, a strong but toxic metal commonly used in demanding aerospace applications.

"The new material we developed is environmentally safe, and while its stiffness equals that of steel, it's only half as dense," said Vecchio. "It performs spectacularly in our depth-of-penetration ballistics tests, but we think its greatest potential may derive from its unique ability to have its structure and properties tailored to meet a wide variety of application-specific engineering requirements."

The new material is made primarily of two lightweight metals. Vecchio alternated layers of aluminium and titanium alloy foils, and compressed and heated them in an inexpensive energy-conserving process. The resulting reaction generated a laminate with two layers: a hard ceramic-like "intermetallic" layer of titanium aluminide, and a pliable layer of residual titanium alloy. The layers can be stacked like one millimetre-thick pages of a book, and even contoured into desired shapes prior to heating.