Home 
News Archive Archiv 2011 International Interest in Research Results of Leoben Materials Scientist
News Archive Archiv 2011 International Interest in Research Results of Leoben Materials Scientist | International Interest in Research Results of Leoben Materials Scientist |
|
|
The scientific work of the Leoben materials scientist Dr. Daniel Kiener met with great interest on an international scale. Following a publication in the scientific journal "Nature Materials" in early summer, new research results by the assistant professor have now been presented in the renowned journal "Nano Letters". Dr. Kiener and his colleague Dr. Andrew M. Minor from the University of California in Berkeley, CA, USA were able to contribute to solving a much disputed issue in his field of research. The scientific community was long challenged by explaining the uncommon mechanical properties of microscopic samples: What makes tiny volumes so extraordinarily strong? This issue lead to the emergence of two major schools of thought. One group argued that in miniaturized samples accordingly small dislocations (the carrier of plastic deformation) will lead to the extraordinarily strength, while the other envisioned that only pristine volumes could exhibit such high strength. The material scientist Dr. Kiener and Dr. Minor from the University of California in Berkeley, CA, USA developed a new method to show that both sides are partly right. In detail, the scientists developed a technique for performing quantitative nano-tensile tests with samples being only 100-200 nm thin (a billion nm equals one m). The tests were performed in situ in a transmission electron microscope, which allows live imaging of individual crystal defects due to its atomic resolution. The results show that the loaded material gets stronger once it contains fewer defects. However, the specimen never got totally defect free, although it sustained stresses above 2 GPa, which it more than a hundred times the macroscopic bulk value. "We measure an increase in material strength with a reduction in defect density, but still observe dislocations as carrier of the plastic deformation," Kiener explained. "These results are important for a basic understanding of the mechanical properties on a nanometer scale, as this limits the reliability of many products in our daily life, such as the nano-electronic components in your cell phone, laptop, ebook, etc. " he continued. These results were published in the renowned journal Nanoletters: ‚Source truncation and exhaustion: Insights from quantitative in-situ TEM tensile testing’ by D. Kiener and A.M. Minor and can be freely accessed thanks to support from the Austrian Science Fund (FWF). Further information: Ass.Prof. Dipl.-Ing. Dr.mont. Daniel Kiener Lehrstuhl für Materialphysik der Montanuniversität Leoben E-Mail: daniel.kiener[at]unileoben.ac.at Tel.: +43/(0)3842/804 412 Article in "Nano Letters"  Ass.Prof. Dipl.-Ing. Dr.mont. Daniel Kiener (Copyright: Foto Wilke Leoben | Mediendienst.com) |