mohsenzaeem's blog

Directional solidification of Al-11 at % Cu is investigated by molecular dynamics (MD) simulations utilizing second nearest neighbor modified embedded atom method (2NN-MEAM) interatomic potential. The condition for directional solidification is produced by imposing dissimilar temperatures at the model boundaries along the [1 0 0] solidification direction to create a temperature gradient. During solidification, the solid-liquid front travels through the Al-Cu liquid along the [1 0 0] direction towards the high temperature end.

Shape memory ceramics, such as yttria-stabilized tetragonal zirconia (YSTZ), offer unique properties including ultra-high operating temperatures and high resistance to oxidation. However, they are susceptible to formation of defects during manufacturing and/or by mechanical deformation. To completely take advantage of their shape memory properties, it is necessary to fully understand the nano-structural evolution of defects under external stimuli. In this study, defect evolution behaviors in YSTZ nanopillars are investigated by atomistic simulations.

We studied the oxidation behavior of face-centered cubic Al0.3CoCrCuFeNi high entropy alloy through first-principles calculations. Three surface orientations were chosen for oxidation, and all the possible combinations of atomic positions at these surfaces were considered. The adsorption energy of oxygen adhesion to the studied surfaces was the lowest for the sites with more neighboring Cr atoms, and the second most favorite site for oxygen adsorption had more neighboring Al atoms.

Formation of solidification defects and their evolution in uniaxial tensile deformation of solidified polycrystalline aluminum (Al) were investigated by molecular dynamics (MD) simulations. First, solidification process was simulated both isothermally and with different quench rates. At the initial stages of nucleation, coherent twin boundaries and/or fivefold twins formed depending on the quench rate or the undercooling temperature. The solidified polycrystalline Al consisted of randomly distributed grains, twin boundaries, and vacancies.

A PostDoc/Research Assistant Professor Position is available immediately on DFT/Phase Field Modeling at the Colorado School of Mines. The applicants should have a PhD degree in Mechanical Engineering, Materials Science or in a relevant field, with a strong background in DFT calculations and phase-field modeling. The project involves simulating structures/phases, kinetics and nano/microstructural evolution in advanced manufacturing.

Shape memory ceramics are a unique family of shape memory materials with a wide variety of applications, such as ultra-high energy dissipation and high-temperature actuation. Along with significant progress in the experimental study of zirconia-based shape memory ceramics in recent years, computational simulations have exhibited powerful capabilities in revealing nano/microstructure-dependent deformation and failure mechanisms in these materials.

N. Zhang, Y. Hong, S. Yazdanparast, and M. Asle Zaeem. Superior structural, elastic and electronic properties of 2D titanium nitride MXenes over carbide MXenes: A comprehensive first principles study. 2D Materials 5 (2018) 045004

Homogeneous nucleation from aluminum (Al) melt was investigated by million-atom molecular dynamics (MD) simulations utilizing the second nearest neighbor modified embedded atom method (MEAM) potentials. The natural spontaneous homogenous nucleation from the Al melt was produced without any influence of pressure, free surface effects and impurities. Initially isothermal crystal nucleation from undercooled melt was studied at different constant temperatures, and later superheated Al melt was quenched with different cooling rates.