Borrowing a method from the field of drug discovery, a team of researchers has developed a material that combines the best properties of ceramics, metals and plastics.
The material, an alloy of iridium, nickel and tantalum, is a bulk metallic glass, an amorphous material made from complex, multicomponent alloys. It has the strength of a ceramic, one of the hardest known materials on Earth and many times stronger than steel. But unlike ceramics, it’s ductile and conductive like metals and it can be molded like a plastic. The results of the research are published today in Nature.
“We were able to develop a material that combines the best of all three material classes,” said Jan Schroers, professor of mechanical engineering & materials science. “The strength combined with plastic-like processing is the most shocking property of the material – it’s unprecedented.”
The researchers created it with what’s known as combinatorial methods, which allow researchers to consider a large number of samples and quickly identify the useful ones. Combinatorial methods first gained prominence in drug discovery as a way to efficiently evaluate and synthesize many small molecules of interest. The materials science community has long been interested in combinatorial methods for their potential to quickly discover new and better materials. In practice, though, the failure rate of identifying desired materials has been high, since the samples often don’t represent the material when scaled for practical application.
Traditional methods for working with iridium and tantalum are extremely limited because both have very high melting points. “With our technique, they are as easy to make as aluminum or copper,” says Yanhui Liu, who has led the six-year development of the method, first as research scientist in Schroers’ lab at Yale and now as a professor at the Chinese Academy of Sciences.
Key to their success is a rapid screening method based on measuring electrical resistivity. It relies on a correlation between a material’s glass-forming ability and its electrical resistivity. Instead of making and characterizing approximately one alloy per day, the team could consider 100 to 1000 alloys. That meant they could significantly speed up the selection process and develop novel materials with multiple fascinating properties.
With the aim of developing a high-strength material that can be processed like plastics, the team created a material that not only has unprecedentedly high strength for metals, but is also heat-resistant to beyond 1,300 degrees Fahrenheit. That suggests a high potential for applications in extreme environments and such uses as high-precision molds. Other applications they’re considering for this particular alloy include catalysts or electrochemical devices. Much of their focus, though, will center on developing more novel materials with sought-after properties.
In addition to its other properties, the material was also developed to be extremely resistant to corrosion.
“Stainless steel is the benchmark for corrosion and our material is many orders of magnitude higher in corrosion resistance,” Yanhui Liu said. “That makes it a fantastic material for both harsh environments and for ambient conditions.”