Super strong nanometals are beginning to play an important role in making cars even lighter, enabling them to stand collisions without fatal consequences for the passengers. A PhD student at Risψ DTU has discovered a new phenomenon that will make nanometals more useful in practice.
Today, the body of an ordinary family car consists of 193 different types of steel. The steel for each part of the car has been carefully selected and optimised. It is important, for example, that all parts are as light as possible because of the fuel consumption, whereas other parts of the car have to be super strong in order to protect passengers in a collision.
Super strong nanostructured metals are now entering the scene, aimed at making cars even lighter, enabling them to stand collisions in a better way without fatal consequences for the passengers. Research into this field is being conducted worldwide. Recently, a young PhD student from the Materials Research Division at Risψ DTU took research a step further by discovering a new phenomenon. The new discovery could speed up the practical application of strong nanometals and has been published in the journal Proceedings of the Royal Society in London.
The research task of the young student, Tianbo Yu, is to determine the stability in new nanostructured metals, which are indeed very strong, but also tend to become softer, even at low temperatures. This is due to the fact that microscopic metal grains of nanostructured metals are not stable -- a problem of which Tianbo Yu's discovery now provides an explanation.
The fine structure consists of many small metal grains. The boundaries between these metal grains can move, also at room temperature. At the same time a coarsening of the structure takes place and the strength of the nanometal is consequently weakened. Tianbo Yu's has now shown that the boundaries of the grains can be locked, when small particles are present and that the solution is technologically feasible. This has paved the way for car components to be made of nanometals.
"We are cooperating with a Danish company and also a Danish consulting engineering company with the purpose of developing light and strong aluminium materials with a view to their application in light vehicles where especially deformation at high rate as in a collision is in focus. The new findings will be included in this work," says Dorte Juul Jensen, head of division and Dr. Techn. She is happy that the excellent findings also have practical applications.
Tianbo Yu comes from Tsinghua University in Beijing -- a leading university within technical scientific research. His studies in Denmark have been financed by the Danish National Research Foundation, which also supports a Danish-Chinese basic research centre in the Materials Research Division, where Tianbo Yu is now employed.
Tianbo Yu is a dedicated and talented researcher, who wishes to pursue a research career in Denmark. His wife is a student at RU (Roskilde University) and along with their studies, they both have decided to put a lot of effort into learning Danish; and they have become good at it. -- All in all, a success for science as well as globalisation.
The above story is based on materials provided by Risoe National Laboratory for Sustainable Energy, the Technical University of Denmark. Note: Materials may be edited for content and length.
- T. Yu, N. Hansen, X. Huang. Recovery by triple junction motion in aluminium deformed to ultrahigh strains. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2011; DOI: 10.1098/rspa.2011.0097
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