Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 38: Liquid and Amorphous Metals
MM 38.2: Vortrag
Mittwoch, 28. März 2012, 15:15–15:30, H 1029
Size-dependent embrittlement in Zr-based bulk metallic glasses and its correlation to shear band velocities — •Peter Thurnheer, David Klaumünzer, Robert Maaß, and Jörg Friedrich Löffler — Laboratory of Metal Physics and Technology, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
Despite extensive research during the last decades, plastic flow in metallic glasses remains a topic of intense debate. Since all metallic glasses are brittle in tension (єp < 0.5%), experimental focus lies on compression testing, where for some alloys, such as Zr52.5Cu17.9Ni14.6Al10Ti5 (Vit105), several percent apparent plasticity can be observed. However, the amount of total plastic strain generated is found to depend highly on sample geometry, temperature and stiffness of both testing equipment and sample. Based on recent research that showed that one serration in the serrated flow regime of the stress-strain curve can be linked to the initiation, propagation and arrest of a single shear band, this work investigates the embrittlement of metallic glasses due to increasing specimen size, by analyzing the dynamics of single serrations with high temporal resolution. Samples with diameters ranging from 2 to 5 mm were tested. Similar to the case of metallic glass embrittlement as a function of increasing temperature, it was found that the total plastic strain to failure decreases with increasing sample diameter and that this decrease correlates with an increase of shear-band velocity during individual serrations.