New metallic glass is both hard and elastic

A metallic glass known as SAM2X5-630 developed by researchers at the University of Southern California (USC) has the ability to be hard, as well as elastic. This remarkable dual-ability makes the substance an ideal material from which to develop a wide range of innovative products.

The material was developed by heating a powdered iron composite up to 1,166 degrees Fahrenheit, followed by rapid cooling. The raw material is heated through the application of a large jolt of electricity, which randomizes the molecules without liquefying the substance.

By heating the material to this exact temperature, and cooling at a specific rate, researchers were able to create a substance which contains molecules in a near-random arrangement, with occasional regions of order.

"It has almost no internal structure, like glass, but you see tiny regions of crystallization. We have no idea why a small amount of crystalline regions in these bulk metallic glasses makes such a big difference under shock loading," said Veronica Eliasson from the USC Viterbi School of Engineering.

This metallic glass is able to withstand heavy impacts without fracturing. Of all known varieties of bulk metallic glasses (BMG's), SAM2X5-630 is able to withstand the greatest impact forces without fracturing. The amount of force required to permanently deform this material is nearly 60 times as great as stainless steel. It is also more than 2.5 times as resilient as tungsten carbide, a high-strengthceramic used in front-line military equipment.

Researchers believe the new metallic glass may be used to construct a new generation of body armor, as well as protective layers for spacecraft. New drill bits could also be constructed, using the unique properties of the new material.

The first amorphous metal was developed in 1960 by researchers at Caltech. Because cooling of the material needs to take place within a small fraction of a second to avoid crystallization, early forms of metallic glass could only be produced in thin layers or wires. Later technology allowed the development of thicker samples, known as BMG's. In more than 55 years of development, several raw materials have been used in the manufacture of metallic glasses.

Development of the new elastic glass was published in the journal Nature Scientific Reports.