Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Discovery of disordered nanolayers in intermetallic alloys: Resolving alloys' strength-ductility trade-off and thermal instability

(A) Atom maps reconstructed using 3D-APT show the distribution of each element. Iron (Fe), cobalt (Co), and boron (B) are enriched (darker in colour) at the nanolayer, whereas nickel (Ni), aluminum (Al), and titanium (Ti) are depleted (lighter in colour) correspondingly. (B) and (C) also show the same results.

CREDIT
Photo source: DOI number: 10.1126/science.abb6830
(A) Atom maps reconstructed using 3D-APT show the distribution of each element. Iron (Fe), cobalt (Co), and boron (B) are enriched (darker in colour) at the nanolayer, whereas nickel (Ni), aluminum (Al), and titanium (Ti) are depleted (lighter in colour) correspondingly. (B) and (C) also show the same results. CREDIT Photo source: DOI number: 10.1126/science.abb6830

Abstract:
Intermetallic alloys potentially have high strength in a high-temperature environment. But they generally suffer poor ductility at ambient and low temperatures, hence limiting their applications in aerospace and other engineering fields. Yet, a research team led by scientists of City University of Hong Kong (CityU) has recently discovered the disordered nanoscale layers at grain boundaries in the ordered intermetallic alloys. The nanolayers can not only resolve the irreconcilable conflict between strength and ductility effectively, but also maintain the alloy's strength with an excellent thermal stability at high temperatures. Designing similar nanolayers may open a pathway for the design of new structural materials with optimal alloy properties.

Discovery of disordered nanolayers in intermetallic alloys: Resolving alloys' strength-ductility trade-off and thermal instability

Hong Kong, China | Posted on July 24th, 2020

This research was led by Professor Liu Chain-tsuan, CityU's University Distinguished Professor and Senior Fellow of the Hong Kong Institute for Advanced Study (HKIAS). The findings were just published in the prestigious scientific journal Science, titled "Ultrahigh-strength and ductile superlattice alloys with nanoscale disordered interfaces".

Just like metals, the inner structure of intermetallic alloys is made of individual crystalline areas knows as "grains". The usual brittleness in intermetallic alloys is generally ascribed to the cracking along their grain boundaries during tensile deformation. Adding the element boron to the intermetallic alloys has been one of the traditional approaches to overcome the brittleness. Professor Liu was actually one of those who studied this approach 30 years ago. At that time, he found that the addition of boron to binary intermetallic alloys (constituting two elements, like Ni3Al) enhances the grain boundary cohesion, hence improving their overall ductility.

A surprising experimental result

In recent years, Professor Liu has achieved many great advances in developing bulk intermetallic alloys (intermetallic alloy is also called superlattice alloy, constructed with long-range, atomically close-packed ordered structure). These materials with good strengths are highly attractive for high-temperature structural applications, but generally suffer from serious brittleness at ambient temperatures, as well as rapid grain coarsening (i.e. growth in grain size) and softening at high temperatures. So this time, Professor Liu and his team have developed the novel "interfacial nanoscale disordering" strategy in multi-element intermetallic alloys, which enables the high strength, large ductility at room temperature and also excellent thermal stability at elevated temperatures.

"What we originally tried to do is to enhance the grain boundary cohesion through optimizing the amount of boron," said Dr Yang Tao, a postdoc research fellow at CityU's Department of Mechanical Engineering (MNE) and IAS, who is also one of the co-first authors of the paper. "We expected that, as we increased the amount of boron, the alloy would retain ultrahigh strength due to its multi-element constituents."

According to conventional wisdom, adding trace amounts (0.1 to 0.5 atomic percent (at. %)) of boron substantially improves their tensile ductility by increasing grain-boundary cohesion. When excessive amounts of boron were added, this traditional approach would not work. "But when we added excessive amounts of boron to the present multicomponent intermetallic alloys, we obtained completely different results. At one point I wondered whether something went wrong during the experiments," Dr Yang recalled.

To the team's surprise, when increasing boron to as high as 1.5 to 2.5 at. %, these boron-doped alloys became very strong but very ductile. Experiment results revealed that the intermetallic alloys with 2 at. % of boron have an ultrahigh yield strength of 1.6 gigapascals with tensile ductility of 25% at ambient temperatures.

By studying through different transmission electron microscopies, the team discovered that when the concentration of boron ranged from 1.5 to 2.5 at. %, a distinctive nanolayer was formed between adjacent ordered grains. Each of the grains was capsulated within this ultrathin nanolayer of about 5nm thick. And the nanolayer itself has a disordered atomic structure. "This special phenomenon had never been discovered and reported before," said Professor Liu.

Their tensile tests showed that the nanolayer serves as a buffer zone between adjacent grains, which enables plastic-deformation at grain boundaries, resulting in the large tensile ductility at an ultrahigh yield strength level.

Why is the disordered nanolayer formed?

The team found that the further increase in boron has substantially enhanced the "multi-element co-segregation" - the partitioning of multiple elements along the grain boundaries. With the advanced three-dimension atom probe tomography (3D APT) at CityU, the only one of its kind in Hong Kong and southern China, they observed a high concentration of boron, iron and cobalt atoms within the nanolayers. In contrast, the nickel, aluminium and titanium were largely depleted there. This unique elemental partitioning, as a result, induced the nanoscale disordering within the nanolayer which effectively suppresses the fractures along grain boundaries and enhances the ductility.

Moreover, when evaluating the thermal response of the alloy, the team found that the increase in grain size was negligible even after 120 hours of annealing at a high temperature of 1050°C. This surprised the team again because most of the structural materials usually show the rapid growth of grain size at high temperature, resulting in strength decrease quickly.

A new pathway for developing structure materials for high-temperature uses

They believed that the nanolayer is pivotal in suppressing growth in grain size and maintain its strength at high temperature. And the thermal stability of the disordered nanolayer will render this type of alloy suitable for high-temperature structural applications.

"The discovery of this disordered nanolayer in the alloy will be impactful to the development of high-strength materials in future. In particular, this approach can be applied to structural materials for applications at high-temperature settings like aerospace, automotive, nuclear power, and chemical engineering," said Professor Liu.

###

Professor Liu is the corresponding author of the paper. The co-first authors are Dr Yang Tao and Dr Zhao Yilu from MNE department at CityU. Other co-authors from CityU included: Professor Huang Chih-ching, Chair Professor of Materials Science and Executive Director of HKIAS, Professor Kai Jijung, Chair Professor of Nuclear Engineering, Li Wanpeng from Department of Materials Science and Engineering, and Dr Luan Junhua at the Inter-University 3D APT Unit.

The funding support of the study included CityU, the Hong Kong Research Grant Council and the National Natural Science Foundation of China.

####

For more information, please click here

Contacts:
P. K. Lee

852-344-28925

Copyright © City University of Hong Kong

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 News Press

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Govt.-Legislation/Regulation/Funding/Policy

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Possible Futures

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Materials/Metamaterials/Magnetoresistance

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Research partnerships

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

'Sudden death' of quantum fluctuations defies current theories of superconductivity: Study challenges the conventional wisdom of superconducting quantum transitions January 12th, 2024

Development of zinc oxide nanopagoda array photoelectrode: photoelectrochemical water-splitting hydrogen production January 12th, 2024

Construction

Temperature-sensing building material changes color to save energy January 27th, 2023

Strain-sensing smart skin ready to deploy: Nanotube-embedded coating detects threats from wear and tear in large structures July 15th, 2022

A sunlight-driven “self-healing” anti-corrosion coating May 27th, 2022

Polymer fibers with graphene nanotubes make it possible to heat hard-to-reach, complex-shaped items February 11th, 2022

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




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project