USMS - Ultrastrong Materials

Background:

The theoretical strength of metals and ceramics is about 10% of their Young’s modulus. Although whiskers reach strength values close to this limit but they cannot be used in the design of load bearing structures. Currently the typical strength of the structural materials in use is only in the range of few % of this theoretical limit. Premature plastic deformation and failure due to flaws are the main reasons for this distinctive lower limit. For engineering applications, adequate fracture toughness is required which permits a ductile behaviour and certain strength even in the presence of flaws or cracks. The strength of the strongest metallic materials is only 10 % of the theoretical limit. Increasing the strength of metallic high strength materials by a few percent is usually associated with an unacceptable decrease in fracture toughness and results in a very flaw sensitive strength similar to that known for ceramics. In pearlitic steel wires it was possible to overcome this 10% limitation significantly. In the last years for the first time a strength of 6.3 GPa was obtained for this material which is about 30% of the theoretical limit or 3 times stronger than other high strength steels. The group of the PI has shown that these wires have an exceptional toughness equivalent to a high damage tolerance. The proposed ERC-grant should permit the analysis of the phenomena for this superior combination of strength and ductility. The knowledge of the essential required architectural features of this nano-composite and the necessary properties of the individual phases as well as their interfaces will be used to design nano-architectures also in other materials to obtain such exceptional properties. The developed skill in the generation of nano-composites from coarse constituents will be used for the production of similar nano-composites, the proof of developed concepts, and the generation of new ultra strong materials.

Acknowledgements: Funding for this research is provided by the European Research Council (ERC Advanced Grant 2013) under the grant number: 340185

Duration: 01.03.2014 - 28.2.2019