Depleted uranium (DU) has been used for decades in anti-tank shells because its ultra-dense. But DU has been a controversial, possibly toxic, method for piercing armor -- blamed by some for so-called "Gulf War Syndrome," by others for birth defects.

A new alloy is emerging that could be a suitable substitute for DU, New Scientist reports.

The U.S. Army is expected to award a contract "for a test batch of 30-millimetre ammunition of the type used by American A-10 'tank buster' aircraft, which fired some 75 tonnes of DU during the recent Iraq conflict," according to New Scientist.

For years, it's been thought that tungsten could replace DU, since it's about as dense, but --hopefully -- not as toxic.

The problem has been that "tungsten shells flatten on impact, forming a mushroom shape. But DU rounds self-sharpen as they deform" -- making the ammunition much more effective.

"Now Liquidmetal Technologies, an R&D company based in Tampa, Florida, says it can get comparable performance from penetrators made of an exotic alloy of tungsten," says New Scientist, which claims the rounds could be ready in as soon as two years.