Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 69: Topical session: Dynamics, relaxation and deformation in deeply supercooled metallic liquids and glasses VII - thermodynamics and structure

MM 69.4: Talk

Thursday, March 23, 2017, 18:15–18:30, IFW A

Characterization of the Fe67Mo6Ni3.5Cr3.5P12C5.5B2.5 bulk metallic glass forming alloy — •Benedikt Bochtler, Oliver Gross, Isabella Gallino, and Ralf Busch — Saarland University, Chair of Metallic Materials, Campus C6.3, 66123 Saarbrücken, Germany

The bulk metallic glass steel Fe67Mo6Ni3.5Cr3.5P12C5.5B2.5 is characterized in detail to evaluate its general applicability [1]. This alloy was designed by Johnson et al. [2] and provides a high critical casting thickness of 13 mm. For the casting of amorphous parts, as well as the processing via thermoplastic forming, thermodynamics and viscosity of an alloy are crucial. The thermophysical properties, including the specific heat capacity, were measured using calorimetric methods. The crystallization behavior of amorphous samples upon heating was characterized by DSC and XRD and a TTT diagram was constructed. The equilibrium viscosity below the glass transition as well as volume relaxation behavior were measured by three-point beam bending and dilatometry, to assess the kinetic fragility. Viscosity in the liquid state was determined, using electromagnetic levitation in microgravity on a reduced gravity aircraft. The alloy displays a strong liquid behavior at low temperatures and a fragile behavior at high temperatures. These results are analog to the ones observed in several Zr-based bulk metallic glass forming liquids [3], indicating a strong to fragile liquid-liquid transition. Ref.: [1] B. Bochtler, et al., Acta Materialia, 118: 129-139, (2016) [2] J.H. Na, et al., US Patent App. 14/335,163; #20150020929 A1, (2015) [3] S. Wei, et al., Nature Comm, 4: 2083, (2013)