Dresden 2020 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 22: Liquid and Amorphous Metals - Metallic Glass

MM 22.4: Talk

Tuesday, March 17, 2020, 11:00–11:15, IFW D

Impact of cryogenic cycling on plastically deformed Pd40 Ni40 P20 bulk metallic glass as studied by tracer diffusion measurements — •Afrouz Hassanpour, Sergiy Divinski, and Gerhard Wilde — Institute of Materials Physics University of Münster Wilhelm-Klemm-Str. 10 48149 Münster Germany

Rejuvenation via cryogenic cycling is an intensively investigated, but still obscure phenomenon for bulk metallic glasses. The calorimetric response of cryo-cycled as-cast and relaxation-annealed PdNiP glasses was found to remain practically unchanged. In the present work, tracer diffusion is used as a probe of structural changes induced by cryo-cycling in PdNiP glasses plastically deformed by high-pressure torsion and cold rolling. The penetration profiles for 57Co atoms reveal specific changes when samples were subjected to cryogenic cycling including both volume and short-circuit (shear band) diffusion contributions. The results substantiate a distinct impact of the cryogenic thermocycling on shear transformation zones and shear band structures, with the latter being characterized by significantly enhanced diffusion coefficients. Thus, the shear bands reveal a kind of kinetic rejuvenation induced by cryo-cycling and apparently a higher susceptibilitay for structural modifications through cryo-cycling as compared with undeformed material, at least for the model PdNiP glass.