IMS Seminar - Avinash M. Dongare (North Carolina State Univ) in Storrs Mansfield on Jun 14, 2012 10:30 AM

"Nanostructured Materials in Extreme Environments: An Atomic Scale Perspective" The improvement in the reliability, lifetime, and efficiency of future energy and defense technologies calls for the design of structural materials that can perform and survive in extremes of high pressure, strain rates, and temperature. Nanostructured materials (nanocrystalline metals, ceramic-particle reinforced metal-matrix nano-composites, etc.), due to their high strength, stiffness, and wear resistance, are an emerging class of materials for applications in the next-generation damage-tolerant structural materials. A reliable performance of these materials requires optimization of the microstructure at the atomic scales that will give the desired properties at the macro-scales. As a result, the White House’s Materials Genome Initiative (MGI) has identified the need for integrated computational, experimental and data informatics tools to significantly reduce the time required for the design of advanced materials by reducing the amount of experimentation needed, and address the most pressing challenges of national importance. My talk will discuss the capability of atomistic simulations to predict the behavior of nanostructured materials in mechanical extremes of high strain rates and high pressures. The detailed atomic level deformation mechanisms, the macro-scale yield behavior, and the micromechanisms related to failure under dynamic loading conditions as characterized using molecular dynamics (MD) simulations will be discussed. The modeling of the behavior of systems with mixed-type of interactions (metal-covalent/ceramic) at the atomic scales, for example, in ceramic-particle reinforced metal-matrix nanocomposites, however, is limited to mostly density functional theory (DFT) calculations. The limitation is largely due to the lack of accurate and computationally efficient interatomic potentials to model the complex multi-component interactions in these materials. A new class of interatomic potentials called the “angular-dependent embedded atom method (A-EAM)” is developed to enable the study of systems with mixed-type of interactions using MD and Monte Carlo simulations. The formulation of the A-EAM potential, the prediction of thermodynamic properties and the ability to investigate the strengthening and failure behavior of ceramic (Si)-particle reinforced metal (Al)-matrix composites at high strain rates and high pressures will be discussed. These simulations provide insights into the effect of length-scales, chemistry and distribution of nanoscale interfaces on the properties and behavior of these materials. I will also discuss my ongoing efforts in the development of multi-scale modeling techniques based on coarse-graining of interatomic potentials to extend the time and/or length scales of current simulations and provide the missing link between the atomistic and continuum (macroscopic) descriptions.

More information available at: http://www.ims.uconn.eduContact Information For further information regarding this event, please contact: Maria Mejiasmaria.mejias@uconn.edu