Materials scientists from North Carolina State University, Raleigh, NC, and Qatar University have developed a new high-entropy metal alloy that, they say, has a higher strength-to-weight ratio than any other existing metal material. High-entropy alloys consist of five or more metals in roughly equal amounts. The researchers say that strong, lightweight materials, may be very useful in prosthetic devices, as well as many other uses.

The NC State research team combined lithium, magnesium, titanium, aluminum, and scandium to make a nanocrystalline high-entropy alloy that has low density, but very high strength, they explained.

“The density is comparable to aluminum, but it is stronger than titanium alloys,” says Dr. Carl Koch, Kobe Steel Distinguished Professor of Materials Science and Engineering at NC State and senior author of a paper on the work. “It has a combination of high strength and low density that is, as far as we can tell, unmatched by any other metallic material. The strength-to-weight ratio is comparable to some ceramics, but we think it’s tougher—less brittle—than ceramics.”

One problem they have encountered, however, is that the alloy is made of 20 percent scandium, which is extremely expensive. They are researching ways in which scandium can be replaced or eliminated to lower the material costs.