Researchers from Oak Ridge National Laboratory
and the University of Tennessee have found a way to cast relatively large
structures from a type of steel whose atomic structure is amorphous, like
glass, rather than the usual orderly crystalline structure of metal.
Amorphous metal alloys are generally stronger and harder than
their crystalline cousins; they enable light sports equipment and strong
medical implants. Amorphous metals are also not magnetic.
Current amorphous alloys are relatively expensive because they
are made from metals like zirconium and palladium. The new steel alloy
is around seven times cheaper than these, and is also stronger and has
higher resistance to corrosion and heat, according to the researchers.
The trick to making structures from amorphous metal is keeping
the metal atoms from arranging themselves into an orderly crystalline
form as it turns from liquid to solid. Past research efforts ran into
trouble when casting amorphous steel objects more than 4 millimeters across.
The researchers used a mix of metals that allows them to drop-cast
their alloy to produce glassy steel rods as large as 12 millimeters. Steel
is a mix of iron and carbon and often contains small amounts of other
elements. The researchers' iron alloy contains chromium, manganese, molybdenum,
carbon, boron and yttrium.
Key to the researchers' mix is the rare earth metal yttrium, which
allowed the mix to remain molten at lower temperatures, and slowed the
growth of crystals.
The new materials can be used for practical applications within
one to two years, according to the researchers. The work appeared in the
June 18, 2004 with issue of Physical Review Letters.
Tools design DNA-nanotube
Five photons linked
Liquid crystal IDs pathogens
drives solar cell
spark efficient LEDs
Nanotubes make fluid
DNA copier uses
Method makes stronger
View from the High Ground Q&A
How It Works
News | Blog
Buy an ad link