Researchers are constantly striving to develop building materials that are not only more durable and flexible, but also more sustainable. With that in mind, the Department of Energy Office of Science recently collaborated with the Lawrence Berkeley National Laboratory and the California Institute of Technology (Cal-Tech) to develop a resilient yet malleable new type of glass that is stronger than steel. The material can also be molded, and it bends when subjected to stress instead of shattering.
The glass is actually a microalloy and features metallic elements such as palladium. This metal has a high “bulk-to-shear” stiffness ratio that counteracts the intrinsic brittleness of glassy materials. The team that developed the material believes that by changing various ratios, they could make it even stronger.
“These results mark the first use of a new strategy for metallic glass fabrication and we believe we can use it to make glass that will be even stronger and more tough,” says Robert Ritchie, a materials scientist who led the Berkeley contribution to the research. “Because of the high bulk-to-shear modulus ratio of palladium-containing material, the energy needed to form shear bands is much lower than the energy required to turn these shear bands into cracks. The result is that glass undergoes extensive plasticity in response to stress, allowing it to bend rather than crack.”
Glass is made up of a non-crystalline, amorphous structure that makes it strong, but brittle. In comparison, metals provide microstructural obstacles that prevent cracks from forming. The new metallic glass feautures a unique chemical composition that features extensive plasticity thanks to the formation of multiple shear bands before the bands turn into cracks.
“Our game now is to try and extend this approach of inducing extensive plasticity prior to fracture to other metallic glasses through changes in composition,” Ritchie says. “The addition of the palladium provides our amorphous material with an unusual capacity for extensive plastic shielding ahead of an opening crack. This promotes a fracture toughness comparable to those of the toughest materials known. The rare combination of toughness and strength, or damage tolerance, extends beyond the benchmark ranges established by the toughest and strongest materials known.”
If that’s true, it could soon be the case that people who live in glass houses have nothing to fear at all.
+ Lawrence Berkeley National Laboratory
Via Eureka Alert
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