A5038651709- Solidification and crystal growth phenomena
- Aluminum Alloy Microstructure Properties
- nanoparticles nucleation surface interactions
- Microstructure and mechanical properties
- Theoretical and Computational Physics
- Adhesion, Friction, and Surface Interactions
- Advancements in Solid Oxide Fuel Cells
- Microstructure and Mechanical Properties of Steels
- Hydrogen embrittlement and corrosion behaviors in metals
- Advancements in Battery Materials
- Metallurgy and Material Forming
- Machine Learning in Materials Science
- Advanced Battery Materials and Technologies
- Numerical methods in engineering
- High Temperature Alloys and Creep
- High-pressure geophysics and materials
- Metallurgical Processes and Thermodynamics
- Quantum many-body systems
- Advanced Battery Technologies Research
- Fluid Dynamics and Thin Films
- Material Properties and Failure Mechanisms
- Advanced Mathematical Modeling in Engineering
- Brake Systems and Friction Analysis
- Force Microscopy Techniques and Applications
- earthquake and tectonic studies
Forschungszentrum Jülich
2016-2025
Jülich Aachen Research Alliance
2017-2024
RWTH Aachen University
2017-2024
Max-Planck-Institut für Nachhaltige Materialien
2010-2018
Max Planck Society
2011-2016
Materials Design (France)
2011-2016
Ruhr University Bochum
2009-2013
Northeastern University
2008-2010
Qatar University
2009
Institute for Solid State Physics and Optics
2007
Fracture is a fundamental mechanism of materials failure. Propagating cracks can exhibit rich dynamical behavior controlled by subtle interplay between microscopic failure processes in the crack tip region and macroscopic elasticity. We review recent approaches to understand dynamics using phase field method. This method, developed originally for transformations, has well-known advantage avoiding explicit front tracking making material interfaces spatially diffuse. In fracture context, this...
We use the phase-field-crystal (PFC) method to investigate equilibrium premelting and nonequilibrium shearing behaviors of $[001]$ symmetric tilt grain boundaries (GBs) at high homologous temperature over complete range misorientation $0<\ensuremath{\theta}<{90}^{\ensuremath{\circ}}$ in classical models bcc Fe. characterize dependence premelted layer width $W$ as a function misorientation. In addition, we compute thermodynamic disjoining potential whose derivative with respect represents...
We present a continuum theory which predicts the steady state propagation of cracks. The overcomes usual problem finite time cusp singularity Grinfeld instability by inclusion elastodynamic effects restore selection tip radius and velocity. developed phase field model for elastically induced transitions; in limit small or vanishing elastic coefficients new phase, fracture can be studied. simulations confirm analytical predictions fast crack propagation.
We present a continuum theory to describe elastically induced phase transitions between coherent solid phases. In the limit of vanishing elastic constants in one phases, model can be used fracture on basis late stage Asaro-Tiller-Grinfeld instability. Starting from sharp interface formulation we derive equations and dissipative kinetics. develop field simulate these processes numerically; limit, it reproduces desired motion boundary conditions. perform large scale simulations eliminate...
The description of surface-diffusion controlled dynamics via the phase-field method is less trivial than it appears at first sight. A seemingly straightforward approach from literature shown to fail produce correct asymptotics, albeit in a subtle manner. Two models are constructed that approximate known sharp-interface equations without adding undesired constraints. Linear stability planar interface investigated for resulting and reduce desired limit. Finally, numerical simulations standard...
The onset of frictional instabilities, e.g. earthquakes nucleation, is intimately related to velocity-weakening friction, in which the resistance interfaces decreases with increasing slip velocity. While this response has been studied extensively, less attention given steady-state velocity-strengthening spite its potential importance for various aspects phenomena such as propagation speed interfacial rupture fronts and amount stored energy released by them. In note we suggest that a...
We investigate the ability of frame-invariant amplitude equations [G. H. Gunaratne, Q. Ouyang, and Swinney, Phys. Rev. E {\bf 50}, 2802 (1994)] to describe quantitatively evolution polycrystalline microstructures we extend this approach include interaction between composition stress. Validations for elemental materials studies Asaro-Tiller-Grinfeld morphological instability a stressed crystal surface, growth from melt, grain boundary energies over wide range misorientation, motion coupled...
The strength and stability of frictional interfaces, ranging from tribological systems to earthquake faults, are intimately related the underlying spatially extended dynamics. Here we provide a comprehensive theoretical account, both analytic numeric, spatiotemporal interfacial dynamics in realistic rate-and-state friction model, featuring velocity-weakening velocity-strengthening behaviors. Slowly extending, loading-rate-dependent creep patches undergo linear instability at critical...
The prediction of the degradation lithium-ion batteries is essential for various applications and optimized recycling schemes. In order to address this issue, study aims predict cycle lives using only data from early cycles. To reach such an objective, experimental raw 121 commercial lithium iron phosphate/graphite cells are gathered literature. analyzed, suitable input features generated use different machine learning algorithms. A final accuracy 99.81% life obtained with extremely...
The influence of different processing routes and grain size distributions on the character boundaries in Li7La3Zr2O12 (LLZO) potential failure through formation percolating lithium metal networks solid electrolyte are investigated. Therefore, high quality hot-pressed pellets synthesised with two distributions. Based electron backscatter diffraction measurements, boundary network including distribution its connectivity via triple junctions analysed concerning Li plating along certain...
We demonstrate the use and benefits of quantum annealing approaches for determination equilibrated microstructures in shape memory alloys other materials with long-range elastic interaction between coherent grains their different martensite variants phases. After a one dimensional illustration general approach, which requires to formulate energy system terms an Ising Hamiltonian, we distant dependent interactions predict variant selection transformation eigenstrains. The results performance...
Abstract (La,Sr)(Co,Fe)O 3‐δ is very common as cathode material in SOFC applications. Sr this type of reactive to form secondary phases with other oxides, which affect micro‐structures and properties the materials, GDC layers ZrO 2 ‐based electrolytes. The Sr‐related degradation issues, Cr poisoning volatile species formation, are studied. As supplement existing experimental knowledge on poisoning, specific thermodynamic aspects for discussed. calculations show that partial pressure pCrO 3...
Quantum annealing is an efficient technology to determine ground state configurations of discrete binary optimization problems, described through Ising Hamiltonians. Here we show that-at very low computational cost-finite temperature properties can be calculated. The approach most at temperatures, where conventional approaches like Metropolis Monte Carlo sampling suffer from high rejection rates and therefore large statistical noise. To demonstrate the general approach, apply it spin glasses chains.
A key issue in understanding and effectively managing hydrogen embrittlement complex alloys is identifying exploiting the critical role of various defects involved. chemo-mechanical model for diffusion developed taking into account stress gradients material, as well microstructural trapping sites such grain boundaries dislocations. In particular, energetic parameters used this coupled approach are determined from ab initio calculations. Complementary experimental investigations that...
We investigate the multiorder parameter phase field model of Steinbach and Pezzolla [Physica D 134, 385 (1999)] concerning its ability to describe grain boundary premelting. For a single order situation solid-melt interfaces are always attractive, which allows us have (unstable) equilibrium solid-melt-solid coexistence above bulk melting point. The temperature-dependent melt layer thickness disjoining potential, interface interaction, affected by choice thermal coupling function measure...
Anode-supported solid oxide fuel cells with different Cr protection layers on the metallic interconnect were operated in a short stack at 700°C for 1240 h. The current density was raised sequentially from 0.5 A cm−2 during first 240 h of operation to 0.75 further 1000 After operation, (La,Sr)(Co,Fe)O3-δ (LSCF) cathode analyzed respect interaction by both wet chemical and microstructural methods. For equipped interconnects coated dense APS layer, amount range few μg. porous WPS coating...
We demonstrate the use of quantum annealing for selection multiple martensite variants in a microstructure with long-range coherency stresses and external mechanical load. The general approach is illustrated martensites four different based on minimization linear elastic energy. equilibrium variant distribution then analyzed under application tensile shear strains values considered tetragonal contributions variants. interface orientations between domains can be explained using perspective...
We predict the structural interaction of crystalline solid-melt interfaces using amplitude equations which are derived from classical density functional theory or phase field crystal modeling. The solid ordering decays exponentially on scale interface thickness at interfaces; overlap two such profiles leads to a short-range interaction, is mainly carried by longest-range waves, can facilitate grain boundary premelting. calculate tail these interactions, depending relative translation...
Frictional interfaces abound in natural and man-made systems, yet their dynamics are not well-understood. Recent extensive experimental data have revealed that velocity-strengthening friction, where the steady-state frictional resistance increases with sliding velocity over some range, is a generic feature of such interfaces. This physical behavior has very recently been linked to slow stick-slip motion. Here we elucidate importance friction by theoretically studying three variants realistic...
We investigate nonlinear elastic deformations in the phase field crystal model and derived amplitude equation formulations. Two sources of nonlinearity are found, one them is based on geometric expressed through a finite strain tensor. This tensor inverse right Cauchy-Green deformation correctly describes dependence stiffness for anisotropic isotropic behavior. In one- two-dimensional situations, energy can be equivalently left The predicted low-temperature effects directly related to...
The ultrafine-grained (UFG) duplex microstructure of medium-Mn steel consists a considerable amount austenite and ferrite/martensite, achieving an extraordinary balance mechanical properties alloying cost. In the present work, two heat treatment routes were performed on cold-rolled Fe-12Mn-3Al-0.05C (wt.%) to achieve comparable with different microstructural morphologies. One was merely austenite-reverted-transformation (ART) annealing other one successive combination austenitization (AUS)...