Regensburg 2016 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 13: Liquid and Amorphous Metals III: Mechanical properties

MM 13.2: Vortrag

Montag, 7. März 2016, 16:00–16:15, H52

Ductility changes in the bulk metallic glass former PdNiP due to micro-alloying by adding Cobalt and Iron — •Niklas Nollmann, Isabelle Binkowski, Harald Rösner, and Gerhard Wilde — Universität Münster

Deformation of bulk metallic glasses (BMGs) at low temperatures and high stresses lead to an inhomogeneous plastic flow. During plastic deformation, bulk metallic glasses show almost no ductility and fail alongside shear bands where the strain is localized. This limited ductility has led to substantial effort in order to improve the plasticity of BMGs. We investigated PdNiP based glasses which feature a rather high ductility in bending, compared to other bulk metallic glasses. By the use of micro alloying, the mechanical properties of metallic glasses can be influenced. Adding Iron or Cobalt to the PdNiP BMG leads to a huge change in ductility. To investigate the reason for these changes, the Poisson's ratios were determined by ultrasonic measurements. Interestingly, the plasticity is not reflected by the high Poisson ratio, which remained unaffected by microalloying within the accuracy of the measurement. While analyzing the dependence of the ductility of the present glasses on relaxation treatments, we utilize the fictive temperature concept to investigate the impact of minor alloying on the relative amount of free volume. Also the critical fictive temperature was measured to characterize the ductility of the new BMGs.