The latest publications

Ultramicroscopy 223 (2021) 113220
© The Authors

Plasmon energy losses in shear bands of metallic glass

This work reveals subtle energy shifts of the Plasmon peak in sheared zones of a metallic glass elaborated by automated routines based on an open source python module (Hyperspy). The signals are characteristic fingerprints and therefore suitable to visualize deformation features in amorphous materials such as shear bands. A model is presented based on Baym theory that suggests two reasons for the plasmon energy shifts.

M. Grove, M. Peterlechner, H. Rösner, R. Imlau, A. Zaccone, G. Wilde

Surface Engineering
© The Authors

A review on coronavirus survivability on material’s surfaces: present research scenarios, technologies and future directions

The present work provides a critical survey about the severity of indirect contact mode transmission and survivability of various coronavirus families on different material surfaces. The possible direction for future research needed to develop antiviral material surfaces that can be regularly used to tackle such pandemic outbreaks is identified. Also, the missing link between the biologist’s approach and the material scientist’s approach in tackling such pandemics is discussed along with scopes and challenges in future interdisciplinary research.

Mohammed Adnan Hasan, A. Carmel Mary Esther, Arjun Dey & Anoop Kumar Mukhopadhyay

Nano Select
© The Authors

A microwave-based one-pot process for homogeneous surface coating: improved electrochemical performance of Li(Ni1/3Mn1/3Co1/3)O2 with a nano-scaled ZnO:Al layer

In this work, a versatile process based on microwave-assisted sol–gel synthesis is introduced in order to apply a surface coating on cathode material for lithium-ion batteries. Here, a nano-scaled Al-doped ZnO (AZO) layer is coated homogeneously onto Li(Ni1/3Mn1/3Co1/3)O2 (NMC111) powder electrode at temperatures below 210 0C within a few minutes. The AZO protective coating on NMC111 powder electrode significantly reduces capacity fading during cycling in the voltage range of 3.0-4.5 V. Furthermore, applying optimal quantities of the coating agent on NMC111 lead to enhanced specific capacities compared to the uncoated material.

Michael Wolff, Sandra Lobe, Christian Dellen, Sven Uhlenbruck, Caue Ribeiro, Xavier H. Guichard, Markus Niederberger, Ardavan Makvandi, Martin Peterlechner, Gerhard Wilde, Dina Fattakhova-Rohlfing, Olivier Guillon

Microscopy and Microanalysis (2020), 1–10

Comparison of Experimental STEM Conditions for Fluctuation Electron Microscopy

STEM Fluktuationselektronenmikroskopie Messungen wurden an amorphen Silizium sowie an dem metallischen Glas PdNiP unter verschiedenen experimentellen Bedingungen durchgeführt. Dabei zeigt sich unter anderem, dass eine Vegrößerung des Elektronenstrahls durch Defokus für diese Messtechnik ungeeignet ist, da dies in einer reduzierten normalisierten Varianz resultiert. Weiterhin spielt die Kohärenz des Elektronenstrahls eine wichtige Rolle für die Experimente. Diese kann durch geometrische Optik an einem mehrlinsigen System theoretisch beschrieben werden. Die theoretischen Erkenntnisse werden durch Fits an experimentelle Elektronenstrahlprofile bestätigt.

Dražen Radić, Sven Hilke, Martin Peterlechner, Matthias Posselt, Gerhard Wilde and Hartmut Bracht

Scripta Materialia 187 (2020) 57 - 62

Tracer diffusion in single crystalline CoCrFeNi and CoCrFeMnNi high-entropy alloys: Kinetic hints towards a low-temperature phase instability of the solid-solution?

Tracer-diffusion of all constituting elements in single-crystalline CoCrFeNi and CoCrFeMnNi is measured in a temperature range from
923 K to 1373 K. Deviations of the otherwise linear Arrhenius-type dependencies indicate the existence of a low-temperature modification of the equiatomic solid-solution phase in CoCrFeMnNi.
Insights into the potential mechanisms of the kinetic anomaly are provided by the determination of the temperature-dependent correlation factors of all elements are determined within the framework of the random alloy model.

Daniel Gaertner, Josua Kottke, Yury Chumlyakov, Fabian Hergemöller, Gerhard Wilde, Sergiy V. Divinski

Acta Materialia, Volume 194, 1 August 2020, Pages 236-248

Experimental and theoretical study of tracer diffusion in a series of (CoCrFeMn)100-xNix alloys

In this paper, the tracer diffusion of all constituting elements is studied at various temperatures in a series of (CoCrFeMn)100-xNix alloys with compositions ranging from pure Ni to the equiatomic CoCrFeMnNi high-entropy alloy. At a given homologous temperature, the measured tracer diffusion coefficients change non-monotonically along the transition from pure Ni to the concentrated alloys and finally to the equiatomic CoCrFeMnNi alloy. This is explained by atomistic Monte-Carlo simulations based on a modified embedded-atom potentials, which reveal that local heterogeneities of the atomic configurations around a vacancy cause correlation effects and induce significant deviations from predictions of the random alloy model.

Josua Kottke, Daniel Utt, Mathilde Laurent-Brocq, Adnan Fareed, Daniel Gaertner, Loïc Perrière, Łukasz Rogal, Alexander Stukowski, Karsten Albe, Sergiy V. Divinski, Gerhard Wilde

Acta Materialia 195 (2020) 446-453

X-ray photon correlation spectroscopy revealing the change of relaxation dynamics of a severely deformed Pd-based bulk metallic glass

This work reveals that the relaxation dynamics of a Pd40Ni40P20 (at.%) bulk metallic glass is accelerated by about a half order of magnitude after plastic deformation by high-pressure torsion processing. A crossover from a stress-dominated to a diffusion-dominated relaxation process occurs with increasing temperature. Deformation-induced changes in topology are responsible for the rejuvenation and the accelerated dynamics.

H. Zhou, S. Hilke, E. Pineda, M. Peterlechner, Y. Chushkin, S. Shanmugam, G. Wilde

Scripta Materialia 188 (2020) 50–53

The role of minor alloying in the plasticity of bulk metallic glasses

Während mit Röntgenbeugung oder selected area electron diffraction keine Unterschiede gefunden und damit keine Korrelation mit der Verformbarkeit erklärt werden kann, liefert Fluktuationselektronenmikroskopie eindeutige Beweise dafür, dass geringfügige Zugaben von Fe oder Co zum ternären Pd40Ni40P20 einen großen Einfluss auf die Mikrostruktur haben. Die Mikrostruktur ist durch die mittelreichweitige Ordnung (MRO) mit Korrelationen der Glasstrukturen über den typischerweise angegebenen 2 nm Bereich hinaus und vor allem durch die jeweilige Diversität charakterisiert, was die Duktilität des Materials direkt beeinflusst. Es wird eine Art MRO-Superstruktur diskutiert. Dies wiederum macht kleinere Zulegierungen sehr vielversprechend, um die Eigenschaften von metallischen Gläsern mittels MRO-Engineering zu optimieren.

Sven Hilke, Harald Rösner, Gerhard Wilde