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[casi] 'Safe' Alternative To Uranium Shells

Public release date: 30-Jul-2003

Contact: Claire Bowles
New Scientist
'Safe' alternative to uranium shells
Contraversial anti-tank shells tipped with depleted uranium may be phased out if an alternative 
material proves its worth. The US Army is expected to award a contract this week for the 
manufacture of prototype ammunition incorporating a "liquid metal" alloy. The new rounds could be 
in service within two years.

Campaigners have complained for years about the potential health effects of DU- it has been linked 
to everything from Gulf War syndrome to birth defects. But the health connection is disputed and 
the military defends its use of DU. All the same, the US Army's Tank-automotive and Armaments 
Command is looking for alternatives in case political pressures force it to abandon DU.

DU has been the material of choice for anti-tank ammunition since the 1970s because it has twice 
the density of lead. And it has two key advantages over pure tungsten, which has a similar density. 
Tungsten shells flatten on impact, forming a mushroom shape. But DU rounds self-sharpen as they 
deform because material breaks away in a way that preserves the shell's shape, a phenomenon known 
as "adiabatic shear banding". DU rounds are also pyrophoric- the fragments ignite in air, torching 
the interior of the target vehicle.

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.

Normally, solid metals are a lattice of tiny crystals. The size of the crystals affects the 
properties of the material which tends to fracture along the boundaries between them. Instead of 
such a metal, the company wants to use an amorphous alloy that has a random arrangement of atoms, 
as in a glass or liquid.

Amorphous tungsten alloy has many of the properties that make DU such an effective penetrator: it 
is self-sharpening and it should also be pyrophoric, says Steve Collier, president of Liquidmetal's 
defence arm.

The new contract is 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.

While many will welcome an alternative to DU, questions remain over the safety of tungsten. 
Fragments of tungsten embedded in flesh have been shown to cause tumours by Alexandra Miller and 
her colleagues at the Armed Forces Radiobiology Research Institute in Bethesda, Maryland. However, 
the toxicity of tungsten when inhaled is believed to be much lower than that of uranium or lead.

"Clearly, tungsten is not radioactive like DU, so there is no hazard from radioactivity," says 
Peter Collins, director of the Royal Society's Science Policy Group. But most casualties will be 
caused in battle, he says: "The most obvious health hazard from any of these things is being hit by 


Author: David Hambling

New Scientist issue: 2 AUGUST 2003

UK CONTACT - Claire Bowles, New Scientist Press Office, London:
Tel: 44-0-20-7331-2751 or email

US CONTACT - Michelle Soucy, New Scientist Boston Office:
Tel: 1-617-558-4939 or email


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