Researchers have developed a super-strong steel that acts more like glass -- and can be used to shield satellites from meteorites, drill through stubborn rock formations or bust through bad guys' underground liars.
The new new steel alloy can withstand pressure and stress of up to 12.5 giga-Pascals (equivalent to about 125,000 atmospheres of pressure) without a scratch, according to researchers at the University of California, San Diego and University of Southern California, who published their findings recently in the journal Nature Scientific Reports.
In comparison, stainless steel has an limit of 0.2 giga-Pascals, while tungsten carbide (a high-strength ceramic used in military armor) is 4.5 giga-Pascals. Only diamonds are tougher, but not so practical for armor or anything else.
"Our material contains additional elements which are not in regular steel," said Olivia Graeve, a professor of mechanical engineering at the Jacobs School of Engineering at UC San Diego. "It has boron, tungsten, silicon, all of these elements allow the material to loose its crystalline structure and become an amorphous metal."
Amorphous metals are a class of materials developed a few decades ago that are extremely tough without becoming brittle.The researchers believe their work on the steel alloy, named SAM2X5-630, is the first to investigate how amorphous steels respond to shock.
The new steel has some regions where the atoms of iron and carbon (elements of steel) are "amorphous" and other areas where they are in a crystalline structure -- like metallic glass.
In fact the steel was fabricated by turning the iron compound is a powder, placed in a dye, and then zapped with a powerful electric current. The jolt superheated the atoms to the point of binding without liquefying it.
The Pentagon's Defense Threat Reduction Agency funded research into this material as a shield for nuclear waste casks that were designed to be stored at the Yucca Mountain nuclear facility, a project that Congress effectively killed in 2008.
The other idea was to use it for a bunker-busting projectile, according to Joe Poon, professor of physics the University of Virginia who has worked on similar amorphous metal research projects.
"One idea is you have some projectile made of super duper materials and it can penetrate the cave or the wall in Afghanistan or other places," Poon said.
Even though the war in Afghanistan is winding down and the nuclear storage problem hasn't been settled, Graeve says the new material has an unexpected side benefit -- it doesn't rust. That means the material could be used in ships or submarines as well.
"There's no oxidization," Graeve said. "Anything that is exposed to salty water, you can coat with this material. It's 1 million times more corrosion resistant than stainless steel."