UCLA Engineers Show New Path to Make Glass as Tough as Metal

Discovery set new record in fracture resistance
propensity of disordered materials

Mathieu Bauchy
Diagram showing the concept of an energy landscape and resulting brittle and ductile fractures.

Jun 17, 2021

UCLA Samueli Newsroom
Through new atomic-level computer simulations, UCLA engineers have opened a path toward developing stronger and tougher glass that can be more ductile than the existing kind.

In a study published in Materials Horizons this past February, the researchers from UCLA and other organizations identified the microscopic reasons that made disordered materials – whose atomic structures are not as perfectly aligned as those of crystals — either brittle and therefore easy to shatter such as glass, or more ductile like steel. This is a significant new finding since brittleness is the main drawback of glass.

“For the first time, we have identified the microscopic origin that governs the brittle-versus-ductile propensity of disordered materials,” said the study leader Mathieu Bauchy.

“For the first time, we have identified the microscopic origin that governs the brittle-versus-ductile propensity of disordered materials,” said the study leader Mathieu Bauchy, an associate professor of civil and environmental engineering at the UCLA Samueli School of Engineering. “This knowledge could revolutionize the design of glass that is still transparent, but tough like metal.”

The research breakthrough could usher in new ways to design buildings with load-bearing windows and other glass structures. Findings from this research can also transform the types of glass used for tough but ultra-flexible electronic screens and fiber optics, as well as new generations of shatter-resistant windshields for cars.

The researchers first ran atomic simulations to access certain microscopic details that are otherwise hidden. They then used an “energy landscape” concept that illustrates the energy of a material in terms of a topographic surface. This is similar to how a topographic map shows the different altitudes of mountains and valleys.

“Based on this observation, we found that the brittle-versus-ductile nature of disordered materials is encoded in the roughness of their energy landscape,” said Bauchy, who is also a computational materials scientist and the director of the UCLA Physics of AmoRphous and Inorganic Solids Lab. “Materials exhibiting ‘rough’ landscapes, with lots of steep mountains and deep valleys, are more brittle than materials that have smooth and flat energy landscapes.”

Building on the results of the theoretical study, Bauchy’s research group, along with collaborators from Denmark’s Aalborg University, are now designing new types of glass that are less brittle than existing ones. The joint effort led to the discovery of a novel transparent glass that set a world-record in fracture resistance — doubling the durability of current smartphone protective screens — while maintaining the glass’ transparency. In April 2021, the researchers published their findings in ACS Applied Materials & Interfaces.

While the theoretical study focused on glass, Bauchy noted that the same theory holds true for a wide range of disordered materials — from gels, pastes and cements to certain metallic glasses and some semiconductor materials.

Longwen Tang, a postdoctoral scientist and member of Bauchy’s research group is the Materials Horizon paper’s lead author. Wei Zhou, a professor of water resources and hydropower engineering at Wuhan University in China, is the study’s co-corresponding author. Other authors on the paper include Han Liu and Tao Du, current and former UCLA civil engineering graduate students respectively; Gang Ma of Wuhan University; and Normand Mousseau of the University of Montreal in Quebec, Canada. The research was supported in part by the National Science Foundation.