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477 results on '"Pauly, S"'

3. Non-monotonic fluctuation of structural heterogeneity in metallic glass due to cyclic rapid heat treatment.

Author

Sun, K., Yuan, X. D., Zhang, N. Z., Jia, Y. F., Tseng, J. C., Kosiba, K., Jia, Y. D., Shuai, C., Pauly, S., and Wang, G.

Subjects
GLASS transition temperature, METALLIC glasses, MOLECULAR dynamics, HEAT treatment, X-ray diffraction
Abstract

Flash-annealing (FA) of metallic glasses (MGs) allows one to modulate their disordered structure. Here, we have flash-annealed a CuZr-based MG below the glass transition temperature at different cycles and generated MGs with various heterogeneous structures. We quantified the glassy structure via the relaxation enthalpy, ΔrelH, which did not significantly change for MGs flash-annealed at a low number of cycles. Their hardness monotonically reduced. However, when more than ten FA cycles were applied, ΔrelH, perceivably decreased, while corresponding hardness increased. High-energy x-ray diffraction analysis revealed that the medium-range ordering of the corresponding structure initially rose and then decreased with an increasing number of FA cycles. This structural change is accompanied by first a hardness decrease followed by an increase. Molecular dynamics simulations showed that throughout the shift from low to high cycles, the structural non-uniformity changed from being non-uniform to more uniform. Through a combination of experiments and simulations, we have shown the non-monotonic relationship between the structural heterogeneity of MGs and cyclic treatments, contributing to a better understanding of the relationship between structural control techniques, microstructure, and properties. [ABSTRACT FROM AUTHOR]

Published
2025
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5. Transformation-mediated Plasticity in CuZr based Metallic Glass Composites: A Quantitative Mechanistic Understanding

Author

Sun, B. A., Song, K. K., Pauly, S., Gararella, P., Liu, C. T., Eckert, J., and Yang, Y.

Subjects
Condensed Matter - Materials Science
Abstract

In this paper, we present a thorough stress analysis of the Cu-Zr metallic-glass composite with embedded B2 particles subject to a martensitic transformation. Within the framework of the Eshelby theory, we are able to explain, in a quantitative manner, (1) the formation of three types of shear bands with distinct morphologies as observed experimentally in the severely deformed Cu-Zr metallic-glass composite and (2) the work hardening ability of the Cu-Zr metallic-glass composite as related to the coupled effects of elastic back stress and elastic mismatch caused by the martensitic transformation. Furthermore, we also discuss the issues about the stress affected zone of the individual B2 phase and the stability of the crystalline-amorphous interface. Given the general agreement between the theoretical and experimental findings, we believe that the outcome of our current work can lead to a deeper understanding of the transformation-induced plasticity in the Cu-Zr based metallic glass composites, which should be very useful to the design of the metallic-glass composites with improved ductility., Comment: 32 pages, 11 figures

Published
2016

8. Influence of the Ag concentration on the medium-range order in a CuZrAlAg bulk metallic glass.

Author

Gammer, C, Escher, B, Ebner, C, Minor, AM, Karnthaler, HP, Eckert, J, Pauly, S, and Rentenberger, C

Subjects
Biochemistry and Cell Biology, Other Physical Sciences
Abstract

Fluctuation electron microscopy of bulk metallic glasses of CuZrAl(Ag) demonstrates that medium-range order is sensitive to minor compositional changes. By analyzing nanodiffraction patterns medium-range order is detected with crystal-like motifs based on the B2 CuZr structure and its distorted structures resembling the martensitic ones. This result demonstrates some structural homology between the metallic glass and its high temperature crystalline phase. The amount of medium-range order seems slightly affected with increasing Ag concentration (0, 2, 5 at.%) but the structural motifs of the medium-range ordered clusters become more diverse at the highest Ag concentration. The decrease of dominant clusters is consistent with the destabilization of the B2 structure measured by calorimetry and accounts for the increased glass-forming ability.

Published
2017

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