Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 58: Liquid and Amorphous Metals

MM 58.1: Talk

Thursday, March 15, 2018, 11:45–12:00, TC 010

Mechanical and thermal properties of PdNiP based bulk metallic glasses — •Niklas Nollmann, Vitalij Hieronymus-Schmidt, Jonas Lübke, Harald Rösner, and Gerhard Wilde — WWU Münster

At low temperatures and high stresses bulk metallic glasses (BMGs) deform inhomogeneously and suffer from a lack of ductility making BMGs unsuitable for many applications. This inhomogeneous deformation can be described in the frame work of a ’fictive temperature’ concept with free volume as a key parameter. An increment or redistribution of the present free volume can be achieved in different ways: i) cryogenic rejuvenation or ii) micro-alloying [2]) may lead to enhanced ductility. In our study we investigated Pd₄₀Ni₄₀P₂₀ based bulk metallic glasses in detail: Adding small amounts of Iron or Cobalt to the Pd₄₀Ni₄₀P₂₀ metallic glass leads to huge changes in ductility. These effects on the mechanical properties by micro-alloying were monitored in bending and compression tests. We also calculated the critical fictive temperature for these different Pd₄₀Ni₄₀P₂₀ based BMGs to show the influence of annealing on the plasticity which is directly linked to the influence of free volume. Moreover, the effects of different degrees of cryogenic rejuvenation due to changes in cycle numbers and resting times at different temperatures of the same metallic glass were investigated with respect to the amount of free volume and the mechanical properties.