Samad Vakili

• Doctor of Engineering
• Postdoctoral Researcher at Max Planck Institute for Sustainable Materials

The phase-field method is used as a basis to develop a strictly mass conserving, yet simple, model for simulation of two-phase flow. The model is aimed to be applied for the study of structure evolution in metallic foams. In this regard, the critical issue is to control the rate of bubble coalescence compared to concurrent processes such as their r...

This paper represents a model for microstructure formation in metallic foams based on the multi-phase-field approach. The model allows to naturally account for the effect of additives which prevent two gas bubbles from coalescence. By applying a non-merging criterion to the phase fields and at the same time raising the free energy penalty associate...

There are several facets of aluminum when it comes to sustainability. While it helps to save fuel due to its low density, producing it from ores is very energy-intensive. Recycling it shifts the balance towards higher sustainability, because the energy needed to melt aluminum from scrap is only about 5% of that consumed in ore reduction. The amount...

Fracture in aluminum alloys with precipitates involves at least two mechanisms, namely, ductile fracture of the aluminum-rich matrix and brittle fracture of the precipitates. In this work, a coupled crystal plasticity-phase field model for mixed ductile-brittle failure modes is formulated and used to investigate the effect of precipitate morphology...

Within diffuse interface models for multiphase problems, the curvature of the phase boundary can be expressed as the difference of two terms, a Laplacian and a second, gradient, term of the diffuse interface variable, ø. In phase field simulations of microstructure evolution, the second term is often replaced by f’(ø) = df/dø, where f(ø) is the pot...

The complex interplay between chemistry, microstructure, and behavior of many engineering materials has been investigated predominantly by experimental methods. Parallel to the increase in computer power, advances in computational modeling methods have resulted in a level of sophistication which is comparable to that of experiments. At the continuu...

The present work addresses a new approach for modeling microstructure formation in metallic foams by coupling the multi-phase-field method with fluid dynamics. The developed model allows for studying bubbles’ rearrangement during the foam formation via slowing down the coalescence process. However, this is only achieved by the expense of reducing t...

This paper represents a model for microstructure formation in metallic foams based on the multi-phase-field (MPF) approach. By the use of a no-coalescence boundary condition within this MPF-framework, it is possible to completely prevent coalescence of bubbles and thus focus on the formation of a closed porous microstructure. A modification of this...

The phase-field method is used as a basis to develop a strictly mass conserving, yet simple, model for simulation of two-phase flow. The model is aimed to be applied for the study of structure evolution in metallic foams. In this regard, the critical issue is to control the rate of bubble coalescence compared to concurrent processes such as their r...

Corrosion resistance of AISI M2 high speed steel samples plasma nitrided in different process gas composition was studied using polarization test. In order to evaluate inherent properties of diffusion zone, the white layer, i.e. compound layer, was removed. Phase structure and surface hardness of samples were characterized using X-Ray diffraction a...

In this paper, the influence of nitrogen content in the plasma gas on the corrosion resistance of austenitic stainlesss steel (304) was studied. plasma nitriding was performed using a direct current (DC) glow discharge reactor at temperatures of 450˚C and 500˚C using H2-N2 gas mixture containing different nitrogen concentration of 25%, 50%, and 75%...