Art of glass

‘Most of us think of glasses as brittle, but our finding shows that any glass can be made ductile or brittle,’ said Jan Schroers, a professor of mechanical engineering and materials science at Yale University , who led the research with Golden Kumar, a professor at Texas Tech University. ‘We identified a special temperature that tells you whether you form a ductile or brittle glass.’

They claim the key to forming a ductile glass is cooling it fast but exactly how fast depends on the nature of the specific glass.

Focusing on a new group of glasses known as bulk metallic glasses (BMGs) researchers are said to have studied the effect of a so-called critical fictive temperature (CFT) on the glasses’ mechanical properties at room temperature.

When forming from liquid, there is a temperature at which glass becomes too viscous for reconfiguration and freezes. This temperature is called the glass transition temperature. Based on experiments with three representative bulk metallic glasses, the researchers said there is also, for each distinct alloy, a critical temperature that determines the brittleness or plasticity of the glass. According to Yale, this is the CFT.