Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > New Model Should Expedite Development of Temperature-Stable Nano-Alloys

The model correctly predicted the material on the left would not be stable at high temperatures and that the material on the right would retain its nanoscale grain size. Click to enlarge.Image: Mostafa Saber.
The model correctly predicted the material on the left would not be stable at high temperatures and that the material on the right would retain its nanoscale grain size. Click to enlarge.

Image: Mostafa Saber.

Abstract:
"A Predictive Model for Thermodynamic Stability of Grain Size in Nanocrystalline Ternary Alloys"

Authors: Mostafa Saber, Hasan Kotan, Carl C. Koch, and Ronald O. Scattergood, North Carolina State University

Published: online Sept. 12, Journal of Applied Physics

DOI: 10.1063/1.4821040

Abstract: This work presents a model for evaluating thermodynamic stabilization of ternary nanocrystalline alloys. It is applicable to alloy systems containing strongly segregating size misfit solutes with a significant enthalpy of elastic strain and/or immiscible solutes with a positive mixing enthalpy. On the basis of a regular solution model, the chemical and elastic strain energy contributions are incorporated into the mixing enthalpy [delta]Hmix, and the mixing entropy [delta]Smix is obtained using the ideal solution approximation. The Gibbs mixing free energy [delta]Gmix is minimized with respect to simultaneous variations in grain size and solute segregation parameters. The Lagrange multiplier method is used to obtain numerical solutions for the minimum [delta]Gmix corresponding to an equilibrium grain size for given alloy compositions. The numerical solutions will serve as a guideline for choosing solutes and assessing the possibility of thermodynamic stabilization. The temperature dependence of the nanocrystalline grain size and interfacial solute excess can be evaluated for selected ternary systems. Model predictions are presented using available input data for a wide range of solvent-solute combinations. The model predictions are compared to experimental results for Cu-Zn-Zr, Fe-Cr-Zr and Fe-Ni-Zr alloys where thermodynamic stabilization might be effective.

New Model Should Expedite Development of Temperature-Stable Nano-Alloys

Raleigh, NC | Posted on September 16th, 2013

Researchers from North Carolina State University have developed a new theoretical model that will speed the development of new nanomaterial alloys that retain their advantageous properties at elevated temperatures.

Nanoscale materials are made up of tiny crystals, or grains, that are less than 100 nanometers in diameter. These materials are of interest to researchers, designers and manufacturers because two materials can have the same chemical composition but very different mechanical properties depending on their grain size. For example, materials with nanoscale grains can be harder and stronger than chemically identical materials with larger grains.

But widespread use of nanoscale materials has long been handicapped by the tendency of nanoscale grains to grow when exposed to elevated temperatures - thereby losing their desired mechanical properties.

This is a problem because creating bulk materials from powdered nanomaterials involves exposure to high temperatures, and even nanomaterials made using other techniques may be exposed to elevated temperatures. The grains in some nanomaterials can even grow - and lose their desired properties - when exposed to room temperature for an extended period of time.

A team of NC State researchers decided to tackle the problem by exploring a concept that had been discussed in the research community for some time: stabilizing nanomaterials by introducing small amounts of an additional element. The idea is that this additional element would serve as a stabilizing agent, migrating to the grain boundaries - or interfaces between grains - and preventing the grains from growing at elevated temperatures. Implementing that concept had been daunting, since there are thousands of possible combinations of these elements.

To turn that idea into a practical solution, the researchers developed a theoretical model to identify suitable candidates that can be used as stabilizing agents.

The theoretical model focuses on alloys that consist of two elements, such as iron and chromium, then allows users to see what would happen if a third element is added to the mix. If users plug the atomic size and thermodynamic properties of each element into the model, the model predicts the grain size of the alloy at any given temperature.

"This model allows anyone to design alloys in a targeted and effective way without having to resort to a trial-and-error approach," says Dr. Ron Scattergood, a professor of materials science and engineering at NC State and senior author of a paper describing the work. "And our experimental results confirm the accuracy of the model."

"We are already using the model in our investigations into lightweight aluminum alloys and high-temperature alloys for nuclear energy applications," says Dr. Mostafa Saber, lead author of the study and a postdoctoral research scholar in materials science and engineering at NC State.

The paper, "A Predictive Model for Thermodynamic Stability of Grain Size in Nanocrystalline Ternary Alloys," was published online Sept. 12 in the Journal of Applied Physics. The paper was co-authored by Dr. Hasan Kotan, a former Ph.D. student and postdoctoral researcher at NC State, and Dr. Carl Koch, Kobe Steel Distinguished Professor of Materials Science and Engineering at NC State. The research was supported by the National Science Foundation and the U.S. Department of Energy.

-shipman-

####

For more information, please click here

Contacts:
Matt Shipman

919-515-6386

Dr. Mostafa Saber
919.515.7217


Dr. Ron Scattergood
919.515.7843

Copyright © North Carolina State University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Download the paper, “A Predictive Model for Thermodynamic Stability of Grain Size in Nanocrystalline Ternary Alloys.”:

Related News Press

News and information

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

Deadline Announced for Registration in 7th Int'l Nanotechnology Festival in Iran July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Discoveries

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

Materials/Metamaterials

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

NUS scientists use low cost technique to improve properties and functions of nanomaterials: By 'drawing' micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applicat July 22nd, 2014

Steam from the sun: New spongelike structure converts solar energy into steam July 21st, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Announcements

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

Deadline Announced for Registration in 7th Int'l Nanotechnology Festival in Iran July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nano-sized Chip "Sniffs Out" Explosives Far Better than Trained Dogs: TAU researcher's groundbreaking sensor detects miniscule concentrations of hazardous materials in the air July 23rd, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE