New ‘High-Entropy’ Alloy Is As Light As Aluminum, As Strong as Titanium Alloys
High-entropy alloys are materials that consist of five or more metals in approximately equal amounts. These alloys are currently the focus of significant attention in materials science and engineering because they can have desirable properties.
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.
“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.”
There are a wide range of uses for strong, lightweight materials, such as in vehicles or prosthetic devices.
“We still have a lot of research to do to fully characterize this material and explore the best processing methods for it,” Koch says.
At this point, the primary problem with the alloy is that it is made of 20 percent scandium, which is extremely expensive.
“One thing we’ll be looking at is whether scandium can be replaced or eliminated from the alloy,” Koch says.
The paper “A Novel Low Density, High Hardness, High-Entropy Alloy with Close-packed Single-phase Nanocrystalline Structures,” is published online in the open-access journal Materials Research Letters. Lead author of the paper is Dr. Khaled Youssef of Qatar University. Co-authors include Alexander Zaddach and Changning Niu, Ph.D. students at NC State; and Douglas Irving, an associate professor of material science and engineering at NC State. The work was supported in part by the National Science Foundation under grant number DMR-1104930.
-shipman-
Note to Editors: The study abstract follows.
“A Novel Low Density, High Hardness, High-Entropy Alloy with Close-packed Single-phase Nanocrystalline Structures”
Authors: Khaled M. Youssef, Qatar University; Alexander J. Zaddach, Changning Niu, Douglas L. Irving, and Carl C. Koch, North Carolina State University
Published: online Dec. 9, Materials Research Letters
DOI: 10.1080/21663831.2014.985855
Abstract: A low density, nanocrystalline high-entropy alloy, Al20Li20Mg10Sc20Ti30 was produced by mechanical alloying. It formed a single-phase fcc structure during ball milling and transformed to single-phase hcp upon annealing. The alloy has an estimated strength-to-weight ratio that is significantly higher than other nanocrystalline alloys and is comparable to ceramics. High hardness is retained after annealing.
Media Contact
More Information:
http://news.ncsu.edu/2014/12/koch-high-entropy-alloy-2014/All latest news from the category: Materials Sciences
Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.
innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.
Newest articles
“Nanostitches” enable lighter and tougher composite materials
In research that may lead to next-generation airplanes and spacecraft, MIT engineers used carbon nanotubes to prevent cracking in multilayered composites. To save on fuel and reduce aircraft emissions, engineers…
Trash to treasure
Researchers turn metal waste into catalyst for hydrogen. Scientists have found a way to transform metal waste into a highly efficient catalyst to make hydrogen from water, a discovery that…
Real-time detection of infectious disease viruses
… by searching for molecular fingerprinting. A research team consisting of Professor Kyoung-Duck Park and Taeyoung Moon and Huitae Joo, PhD candidates, from the Department of Physics at Pohang University…