Argonne nanocrystal

Nanocrystal imaging by the Argonne National Laboratory

Nanotwins team

The nanotwin scientists gathered at a 2010 workshop.

Micrograph

Nanotwins under the electron microscope

CAS-Croucher Joint Labs

The CAS-Croucher Funding Scheme for Joint Laboratories is the outcome of an agreement between The Chinese Academy of Sciences (CAS) and the Croucher Foundati...

Nanotwinned materials display unique properties

Nano-science and technology is an internationally important scientific field with huge potential development and significance in the future. Nano-twinned metals an area of high research interest. 

Nano-twinned metals bring a chance to achieve high strength and high ductility in metals.

Professor Jian Lu

Nano-science and technology is an internationally important scientific field with huge potential development and significance in the future. Nano-twinned metals an area of high research interest.

Although metals have been known and used by mankind for thousands of years, metals are constantly being refined and improved. The ability to create structural materials of high yield strength yet with high ductility has been long-term pursuit of material scientists. However, when a metal’s strength is increased, ductility drops very quickly. Scientists are trying to address this by re-designing the material’s composition, that is, they are going small – nano- small.

Research by Professor Jian Lu and his colleagues have shown that the properties of well-known metals can be improved by refining their interior structure. Not only that, but completely new properties and combinations of properties may be achieved with these new materials. The primary aim is to understand the mechanism by which the internal structures of nano-twinned metals govern their properties by conducting advanced investigation into metals with a wide range of well-defined internal structures. As well as the pursuit of scientific understanding, the aim is that by “tailoring” nano-metals to the manipulation of properties, a number of these applications will be used in technology and industry.

The IMR-CityU Joint Laboratory is exploring ways to link emerging metals with internal structures of nanometer dimensions and new functional and structural properties with metals of relatively coarse internal structures, typical of today’s industrial materials. One example is nano-twinned copper (Cu) thin films which has high strength and high ductility in addition to good electrical conductivity. A surface load is applied copper that is in sheet, cylinder or other form to divide the grain of the material to nano size. It’s a chemical rather than a mechanical process. The process is repeated until the grain reaches nano size.

“When we define the nano materials that means the basic structure should be lower than 100 nano. We have sucessfully produced nanotwins with twin spacing around 5-10 nanometres,” says Lu.

These materials will have valuable applications in automotive, aerospace and nuclear industries. But research of this nature is a long process and can be unpredictable. “Sometimes you have good results at the beginning and then the properties can drop very quickly. For some other industries the application may be quicker, for example, automotive. But for aerospace application we need typically five to ten years to integrate a new material and for nuclear it’s even longer,” Lu explains.

Professors Jian Lu and Ke Lu began working together 15 years ago, and will continue to do so thanks to financial support from the Croucher Foundation. In addition to facilitating research in Hong Kong and the Mainland, the collaboration will bridge multiple disciplines in science and technology.