Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 46: Liquid and Amorphous Metals

MM 46.5: Vortrag

Mittwoch, 14. März 2018, 18:00–18:15, TC 010

Abnormal structural relaxation spectrum observed by dynamic mechanical analysis in an Au-based bulk metallic glass — •Maximilian Frey, Nico Neuber, Isabella Gallino, and Ralf Busch — Chair of Metallic Materials, Saarland University, C6.3, 66123 Saarbrücken, Germany

The structural relaxation time spectrum of a recently developed gold-based metallic glass former is investigated via isochronal temperature scans performed with a dynamic mechanical analyzer. The α-relaxation event for each applied measurement frequency manifests as a maximum in the loss modulus curve. The respective frequency-temperature data points are pictured in an Arrhenius plot and used to evaluate the temperature dependence of the structural relaxation time in the framework of Angell's fragility concept. At low measurement frequencies, the supercooled liquid exhibits a strong temperature dependence, which is in agreement with recent results obtained by calorimetric and thermomechanical studies. For intermediate frequencies, the single maximum peaks of the loss modulus curves perform an unusual splitting in several distinguishable peaks. By further increasing the measuring frequencies, the normal single peak appearance is restored, but with a distinctly more fragile temperature behavior. Calorimetric and thermomechanical studies are performed and compared to the dynamic mechanical data set. Taking recent literature findings for similar alloys into account, the results can be most likely interpreted as the fingerprint of a strong-to-fragile transition event.