EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

This talk will first distinguish the most relevant issues concerning uncertainty in developing models for structure-property relations of materials to support development and deployment in applications. Both model form uncertainty and uncertainty of model parameters will be considered, with a focus on nonequilibrium dislocation-mediated properties/responses of metallic systems. We will...

Enhancing trust in in silico approaches is a fundamental challenge. The uncertainties associated with simulations and mathematical models limit the degree of confidence in their outcomes. Thus, quantifying these uncertainties will play an important role in empowering this approach, in particular when considering models of material systems that will be implanted into the body. The ability of...

Motivated by the limitations of conventional coarse-grained molecular dynamics for simulation of large systems of nanoparticles and the challenges in efficiently representing general pair potentials for rigid bodies, we present a method for interpolating general rigid body pair potentials, based on a specialized type of deep neural network, that maintains essential properties such as...

Electro-magnetic induction heating is a challenge to model, due to the nonlinear nature of the magnetic hysteresis curve and the temperature dependency of this curve and several other electro-physical properties, which lead to a recursive cycle of influence between the electro-magnetic and thermal physics domains. Further intricacies arise once phases and stresses are considered. The heating...

I will present a methodology of constructing phase diagrams by machine-learning the free energy function from data resulting from molecular simulations (such as lattice dynamics, phase coexistence simulations, or phonon calculations). In a nutshell, the methodology can be described as thermodynamic integration, but with active sampling and uncertainty estimation capabilities. This methodology...

Interstitial diffusion occurs in a variety of applications as gaseous nitriding (diffusion of nitrogen atoms), oxidation of metals (diffusion of oxygen atoms), or structural embrittlement due to hydrogen (diffusion of hydrogen atoms). Today, the effect of stresses (whether applied or residual) is important studies in several research applications to improve the mechanical characteristics of...

The use of bainitic steels in the steel industry has significantly increased over time due to their potential to combine high strength and high ductility. Therefore, modelling the complex microstructural transformation of bainite has been a topic of intensive research over the last years. Bainite occurs as upper and lower bainite, distinguished by the size and place of carbides precipitation....

The phase-field method has provided a powerful tool for studying grain growth over the last decades. Thanks to its diffuse character, it has been efficiently applied to the modelling of microstructure evolutions involving complicated topological transformations, without explicitly tracking the interface positions. However, in order to numerically resolve the diffuse interfaces, an interface...

In welding processes, a large melt pool is developed when the heat source passes the top surface of the weld part. Fluid flows develop thereafter in this domain mainly induced by the Marangoni effect. This fluid flow has influences on the microstructure evolution during solidification stage. Up to now, despite its significant effect, few researches take into account the fluid flow phenomenon...

Introducing metastable austenite in steels can be essential for obtaining improved mechanical properties such as ductility, toughness and fatigue resistance [1]. The austenite to martensite transformation leads to increased plastic deformation by means of the transformation induced plasticity (TRIP) effect. The prediction of the deformation induced by the martensitic transformation process is...

A thermodynamically rigorous model is proposed to simulate dislocation dynamics in crystalline materials subjected to rapid/gradual temperature changes. The proposed model, called the Thermal Field Dislocation Mechanics (T-FDM) model [1], is a strong coupling of the FDM approach [2] with the heat transfer problem based on the concept of thermal quasi-dislocations [3]. Its novelty lies in its...

Modeling of induction hardening is a complicated task due to involvement of multiple physical processes. One has to solve the highly nonlinear coupled electromagnetic, thermal, mechanical and metallurgical problems with proper boundary conditions. Finite element methods (FEM) are a good choice for a physics-based description of complex systems such as Induction hardening. However, the full...

The growing requirements in the power density of gears, driven by the wind industry, enhance the need for further development of the methods for assessing the risk of material failure. Broadly applied, the case-hardening process provides beneficial compressive residual stresses and hardness to the gear’s tooth surface. However, the subsequent tensile residual stresses introduced in the...

Heat treatment and grinding are usually the last steps in the manufacturing chain of highly loaded mechanical components, which have a significant impact on the component’s performance. For instance, the load carrying capacity of case-hardened gears strongly depends on the surface integrity in terms of microstructure, hardness and residual stresses. The surface layer is exposed to a...

Inter-granular failure of nickel (Ni) single grain boundaries (GBs) due to the segregation of sulfur (S), hydrogen (H) and their co-segregation has been investigated by means of Density Functional Theory (DFT) calculations and micro cantilever bending test. The results of DFT calculations have been used in a McLean-isotherm-based thermokinetic model to estimate S and H content at a...

The propagation of short cracks in FCC metals is highly influenced by the surrounding microstructure, particularly the one generated by 3D dislocation configuration. A reliable tool to model crack - dislocation microstructure interaction is Discrete Dislocation Dynamics (DDD). DDD is a numerical method to simulate the movement of dislocations under external loading and it is based on an...

The comprehension of fundamental mechanisms leading to the formation and evolution of extended defects such as dislocation loops and cavities is crucial to understand the behaviour of materials under extreme conditions [1,2]. Underlying phenomena are hard to capture, either by numerical simulations or by experimental approaches. Thus building a complete mathematical formalism which can be...

Nuclear fusion is potentially an important future source of energy. Critical for the development of an economically viable fusion reactor are the integrity and lifetime of the so-called divertor. Through this component, energy in the form of heat is extracted and tungsten is the commonly chosen material for it. Although tungsten behaves relatively ductile at elevated temperatures, the failure...

Si epitaxy is an important process in semiconductor technology because it enables the growth of thin crystalline layers with superior precision if the interaction of process conditions and layer growth is well understood and carefully controlled.

We present simulation models of reactor scale computational fluid dynamics (CFD), coupled with surface chemistry models for the growth of Si and...

We present a multiscale method for the simulation of thin film deposition processes, which couples atomistic simulation methods with event-based stochastic modelling. Our approach aims at physical vapor deposition (PVD) processes, but extends to chemical vapor deposition (CVD), atomic layer deposition (ALD) processes, and possibly liquid-phase deposition and etching processes.

Popular...

Phonon transport is fully determining the elastic wave propagation and the thermal conductivity in non-metallic crystalline solids. A typical phonon spectrum involves phonons with a mean free path from nanometers up to millimeters [1], which are frequently comparable or larger than the relevant material or structural length scales. At this length scales, the diffusive picture is replaced by...

The thermo-fluid simulation of metal transfer and melt pool with gas metal arc heat source gives access to an in-depth understanding of the process. However, to be reliable the computed data must be validated with experimental measurements. The common validation method largely depends on the conformance of the fusion zone profile between the computed and the post-build metallographic...

With the development of electronics miniaturization, magnetic components are strongly emerging as major parts for supplying the torque in the mini-operating system. Further, a three-dimensional flux design should be required for the hard-magnetic components having two or more anisotropic axes, in order to operate efficiently within the limited component size. In this respect, magnetic metal...