According to a novel study by Rice scientists Peter Wolynes and former graduate student Apiwat Wisitsorasak lays a foundation to estimate how all sorts of glass morphy over time when they are placed under mechanical stress. Their formulas could aid researchers and manufacturers make glass better for particular applications.
Metallic glasses are alloys that possess a glass-like disordered structure rather than just the polycrystalline structures of familiar metals. They can be both ductile and brittle to degrees and can be prepared into intricate shapes, such as the heads of golf clubs. Unlike window glass, they are highly conductive and may be essential for electronics.
Outwardly, glass may appear solid, but the random assortment of molecules inside is always moving. Wolvnes says, “It has been popular for decades that when compressed, glasses will prepare shear bands, lines that localize the strain. Numerous ideas have been placed forwards about this occurs, but now the Rice group can explain the procedure employing a basic theory of how glasses prepare based on energy landscapes.
Wolynes has regulated his long-term study of the molecular properties of the glass at the Rice’s Centre for Theoretical Biological Physics, where he also introduced the physics of energy landscapes for DNA and protein folding. His motivation for the novel study was to witness if the formation of shear bands could be explained through regular computations that illustrate how stress transforms the rate of atomic rearrangement in the glass.
“My immediate interest is to reveal that this procedure of the shear bands, which is a noticeable thing in metallic substances, can be comprehended as a part of the unified theory of glasses,” he confirms. The theory, formed over decades by Wolynes and his team members, illustrated numerous aspects of how glasses prepare when a liquid is cooled.
He considered two factors prompt the formation of shear bands in metallic glasses. ‘One is that when glass is prepared, it is a little weaker in few places than the others. In that respect, the bands are partially programmed into the glass. The other factor is the randomness,” he says. “Entire chemical reactions need concentrating energy in few specific mode of movement, but movement in glass is particularly intricate, so you have to wait around for an activating event to occur by chance. You need a kind of nucleation event.”
These potentially random ‘activation events’, molecular couplings that occur naturally as a supercooled liquid flows, become rare when the glass settles into its structure but ramp up when the glass is stressed. The events boost the cooperative motion of adjacent molecules and ultimately lead to shear bands
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