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Generalized stacking fault energies, ductilities, and twinnabilities of CoCrFeNi-based face-centered cubic high entropy alloys

Effects of Cu, Mn, Al, Ti, Mo on generalized stacking fault energies, Rice-criterion ductilities, and twinabilities of CoCrFeNi-based face-centered cubic high entropy alloys were investigated using density functional theory calculations. The calculated barrier energies and twinnabilities revealed that the addition of Ti or Mo increased the tendency of dislocation glide and deformation twinning, while addition of Mn, Cu and relatively high amount of Al facilitated dislocation gliding and martensitic transformation. Low amount of Al resulted in only dislocation gliding.

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Effects of specimen size and yttria concentration on mechanical properties of single crystalline yttria-stabilized tetragonal zirconia nanopillars

The nanoscale plastic deformation of yttria-stabilized tetragonal zirconia (YSTZ) is highly dependent on the crystallographic orientations, i.e., dislocation is induced when the loading direction is 45° tilted to {111} and {101} slip planes, while tetragonal to monoclinic phase transformation dominates the plastic deformation when loading direction is perpendicular to the slip planes.

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Investigating phase formations in cast AlFeCoNiCu high entropy alloys by combination of computational modeling and experiments

Selection and thermal stability of phases are important in design of high entropy alloys (HEA). In this study, phase formations in cast AlFeCoNiCu HEA were investigated. Ab-initio molecular dynamics (AIMD) simulations were used to determine crystal structures of phases at different temperatures in equiatomic composition of AlFeCoNiCu. The AIMD results showed a possible coexistence of a face-centered cubic (fcc) phase and a bodycentered cubic (bcc) phase at the room temperature and indicated stabilization of a single fcc phase above 1070 K at the equiatomic composition of AlFeCoNiCu.

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Call for Abstracts, ASME 2017 IMECE, 3-9 November 2017, Tampa, Florida

Call for Abstracts, ASME 2017 IMECE, 3-9 November 2017, Tampa, Florida

Track: Materials: Genetics to Structures

Symposium: 11‐6 Phase Transformations in Materials Processing and Their Effects on Mechanical Properties

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Call for Abstracts, ASME 2017 IMECE (Tampa, Florida): Phase Transformations in Materials Processing and Their Effects on Mechanical Properties

Call for Abstracts, ASME 2017 IMECE, 3-9 November 2017, Tampa, Florida

Track: Materials: Genetics to Structures

Symposium: 11‐6 Phase Transformations in Materials Processing and Their Effects on Mechanical Properties

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Effects of SiC, SiO2and CNTs nanoadditives on the properties of porous alumina-zirconia ceramics produced by a hybrid freeze casting-space holder method

Highly porous alumina-zirconia ceramics were produced by adding space-holder materials during freeze casting. To increase the strength of porous ceramics, different amounts of nanoadditives (silicon carbide-SiC, silica-SiO2, and multi-wall carbon nanotubes-CNTs) were added. Space-holder materials were removed by preheating, and solid samples were produced by sintering. Up to 68% porosity was achieved when 40% space-holder was added to the solid load of slurry. Wall thicknesses between pores were more uniform and thinner when nanoadditives were added.

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Quantitative phase-field crystal modeling of solid-liquid interfaces for FCC metals

This work deals with the quantification and application of the modified two-mode phase-field crystal model (M2PFC; Asadi and Asle Zaeem, 2015) for face-centered cubic (FCC) metals at their melting point. The connection of M2PFC model to the classical density functional theory is explained in this article. M2PFC model in its dimensionless form contains three parameters (two independent and one dependent) which are determined using an iterative procedure based on the molecular dynamics and experimental data.

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Formation path of delta hydrides in zirconium by multiphase field modeling

A multiphase field model is developed to study the effects of metastable ζ and γ hydrides on the nucleation and growth of the stable δ hydrides in α zirconium matrix.  Acta Materialia 123 (2017) 235-244 

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Call for Abstracts_ Martensitic Transformations in Non-Metallic Materials in ICOMAT 2017_Chicago July 9-14, 2017

Call for abstracts for the symposium on Martensitic Transformations in Non-Metallic Materials in the International Conference on Martensitic Transformations (ICOMAT) 2017.

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Competing mechanisms between dislocation and phase transformation in plastic deformation of single crystalline yttria-stabilized tetragonal zirconia nanopillars

Molecular dynamics (MD) is employed to investigate the plastic deformation mechanisms of single crystalline yttria-stabilized tetragonal zirconia (YSTZ) nanopillars under uniaxial compression. Simulation results show that the nanoscale plastic deformation of YSTZ is strongly dependent on the crystallographic orientation of zirconia nanopillars. For the first time, the experimental explored tetragonal to monoclinic phase transformation is reproduced by MD simulations in some particular loading directions.

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Two PhD positions are available immediately in Computational Mechanics & Materials

Two PhD positions are available immediately in Computational Mechanics & Materials.

One project (NSF grant) is about multi-phase field modeling of formation and evolution of intermetallics and oxides at high temperatures in advanced high strength steels. Another project (NSF grant) is about multi-phase field modeling of evolution of oxide bifilms in solidification of metals. 

 

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The anisotropy of hexagonal close-packed and liquid interface free energy using molecular dynamics simulations based on modified embedded-atom method

This work aims to comprehensively study the anisotropy of the hexagonal close-packed (HCP)-liquid interface free energy using molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM). As a case study, all the simulations are performed for Magnesium (Mg). The solid-liquid coexisting approach is used to accurately calculate the melting point and melting properties. Then, the capillary fluctuation method (CFM) is used to determine the HCP-liquid interface free energy and anisotropy parameters.

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postdoctoral position - phase field modeling

A postdoctoral research associate position is available immediately in the Computational Materials & Mechanics Laboratory at Missouri University of Science and Technology (Rolla), http://web.mst.edu/~aslezaeemm/

Candidates need to have a strong background in Phase Field Modeling (PFM).

Interested candidates should send their CV and two to three of their journal articles (in PFM area) to Prof. Zaeem at zaeem@mst.edu.

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Two PhD positions are available immediately in Computational Materials & Mechanics

Two PhD positions are available immediately in the Computational Materials & Mechanics Laboratory at Missouri University of Science and Technology (Rolla), http://web.mst.edu/~aslezaeemm/.

The project is about multi-phase field modeling of formation and evolution of intermetallics and oxides at high temperatures. 

 

Candidates should have a master's degree in materials science and engineering, mechanical engineering, solid-state physics, or applied mathematics. A background in phase field modeling is desired.

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Postdoc position in Computational Materials & Mechanics

A postdoctoral research associate position is available immediately in the Computational Materials & Mechanics Laboratory at Missouri University of Science and Technology (Rolla), http://web.mst.edu/~aslezaeemm/

Candidates need to have a strong background in Molecular Dynamics (MD) or Phase Field Modeling (PFM).

Interested candidates should send their CV and three of their journal articles (in MD or PFM area) to Prof. Zaeem at zaeem@mst.edu.

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Two PhD positions are available immediately - Computational Materials & Mechanics

Two PhD positions are available immediately in the Computational Materials & Mechanics Laboratory at Missouri University of Science and Technology (Rolla), http://web.mst.edu/~aslezaeemm/:

1. Multi-phase field modeling: defect formation and evolution during dendritic solidification of aluminum alloys

2. Molecular dynamics simulations of properties of oxides

 

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Call for Abstracts _TMS 2016: Additive Forming of Components - Tailoring Specific Material Properties in Low Volume Production

Advancements in additive manufacturing technology have created the ability to design and construct parts with geometries and properties that cannot be achieved through traditional machining processes. This ability has promoted new design strategies whose success relies on close integration of engineering with materials science. Of particular interest is tailoring specific material properties in low-volume production.

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A modified two-mode phase-field crystal model applied to face-centered cubic and body-centered cubic orderings

In this work, we present a modified two-mode phase-field crystal (PFC) model for nano-structural evolution of materials. The model is used to study both the face-centered cubic (FCC) and body-centered cubic (BCC) orderings, as well as the solid–liquid coexisting phenomenon. This two-mode PFC model incorporates three parameters in its formulation and damps out the dynamics of the system, except near the first two critical wavelengths.

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Effect of variant strain accommodation on the three-dimensional microstructure formation during martensitic transformation: Application to zirconia

This paper computationally investigates the effect of martensitic variant strain accommodation on the formation of microstructural and topological patterning in zirconia. We used the phase-field technique to capture the temporal and spatial evolution of embryonic formation of the monoclinic phase in tetragonal single crystals. The three-dimensional simulations were able to capture the formation of all the possible monoclinic variants. We used the multivariant single embryo as an initial condition to mitigate the lack of nucleation criteria at the mesoscale.

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Quantitative modeling of the equilibration of two-phase solid-liquid Fe by atomistic simulations on diffusive time scales

Molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM) and a phase-field crystal (PFC) model are utilized to quantitatively investigate the solid-liquid properties of Fe. A set of second nearest-neighbor MEAM parameters for high-temperature applications are developed for Fe, and the solid-liquid coexisting approach is utilized in MD simulations to accurately calculate the melting point, expansion in melting, latent heat, and solid-liquid interface free energy, and surface anisotropy.

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Two-phase solid–liquid coexistence of Ni, Cu, and Al by molecular dynamics simulations using the modified embedded-atom method

The two-phase solid–liquid coexisting structures of Ni, Cu, and Al are studied by molecular dynamics (MD) simulations using the second nearest-neighbor (2NN) modified-embedded atom method (MEAM) potential. For this purpose, the existing 2NN-MEAM parameters for Ni and Cu were modified to make them suitable for the MD simulations of the problems related to the two-phase solid–liquid coexistence of these elements.

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A Review of Quantitative Phase-Field Crystal Modeling of Solid–Liquid Structures

Phase-field crystal (PFC) is a model with atomistic-scale details acting on diffusive time scales. PFC uses the density field as its order parameter, which takes a constant value in the liquid phase and a periodic function in the solid phase. PFC naturally takes into account elasticity, solid–liquid interface free energy, surface anisotropy, and grain boundary free energy by using this single-order parameter in modeling of coexisting solid–liquid structures.

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TMS 2015 Meet the Candidate Poster Session---deadline for abstract submission is extended to December 15, 2014

The TMS Young Professionals Committee is organizing a "Meet the Candidate Poster Session" in conjunction with the general poster session of TMS 2015. This event is designed to create networking opportunities for young professionals and hopefully help them discover prospects for future employment. The deadline for abstract submission is extended to December 15, 2014. http://www.programmaster.org/TMS2015

 

The Meet the Candidate Poster Session will provide the opportunity for

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PhD positions available immediately at Missouri S&T (Rolla)

Two PhD positions are available immediately in the Computational Materials & Mechanics Laboratory at Missouri University of Science and Technology (Rolla):

1.  Density functional theory calculations: Advanced High Strength Steels

2.  Multi-phase field modeling: Boride Ceramics with Improved Fracture Toughness at Elevated Temperatures

 

Candidates should have a master's degree in mechanical engineering, materials science and engineering, solid-state physics, or applied mathematics. Experience in DFT, MD, or phase field modeling is desired.

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