Metallic glass can be used as an adhesive to bond different materials together, new research shows. The work could develop into a strategy for manufacturing and customizing the properties of composites.
A long-term goal of materials scientists is the production of materials with special properties. To accomplish this, the formation of composites by combining two or more materials has emerged. To date, due to their thermoplasticity, thermoplastic polymers are the most common binders or adhesives used to make composite materials. Crystalline metallic materials have excellent mechanical properties, which makes them desirable components of composite materials, but their lack of thermoplasticity has hitherto prevented their use as binders.
When investigating the thermoplastic properties of metallic glasses, Jiang Ma and his group at Shenzhen University in China found that they behave similarly to polymers. “That’s why the idea arose to combine materials with metallic glasses,” says Ma.
Now Ma’s team has developed a metallic lanthanum-based glass that also contains aluminum, nickel, copper and cobalt. It is a metallic solid material at room temperature and becomes viscous when heated. To use the material as an adhesive, the researchers mixed small particles of the metallic glass with particles of the components of a composite material and then applied heat and pressure. They tuned the mechanical, magnetic, and electrical properties of the resulting composite by changing the relative amount of metallic glass in the composite. “The manufacturing process is very simple, requiring relatively low temperatures and voltages,” explains Ma. “No additional additives are required; therefore, the composition of the composites can be precisely controlled. This allows the power to be regulated precisely. ‘
Researchers used the metallic glass to bond a number of materials, including high entropy alloys, ceramic insulators, and iron-based metallic glasses. However, Ma says it is not limited to these. “Almost all solid materials can be glued together with the metallic glass adhesive, so this work is important.”
The work shows that “a metallic glass in particle form can be mixed with another phase and compressed into composite materials when hot. Choosing a lanthanum-based metallic glass with a low glass transition temperature makes molding and bonding easier, ‘comments Lindsay Greer, materials chemist at the University of Cambridge, UK. But adds, “It remains to be seen whether other metallic glasses could be used and whether the resulting composites can outperform their conventional counterparts.”