1. Density Functional Theory HΨ = EΨ Density Functional Theory HΨ = EΨ E-V curve E 0 V 0 B B’ E-V curve E 0 V 0 B B’ International Travel What we do Why computational? broad applications | intellectually challenging | more publications | green | economical Phases Research Lab Materials Science | Physics | Chemistry | Thermodynamics 1.NSF: “SEP Collaborative: Routes to Earth Abundant Kesterite- based Thin Film Photovoltaic Materials” 2.NSF: “Computational and Experimental Investigations of Magnesium Alloys” 3.NETL: “Computer-Aided Development of Novel New Materials for High Temperature Applications” 4.US Army Research Laboratory: “Computational Thermodynamic Modeling and Phase Field Simulations for Property Prediction in Advanced Material Systems” 5.AirProducts, Inc.: “Thermodynamic modeling of perovskites” 6.US Air Force: “Corrosion protection for magnesium alloys – development of novel, environmentally compliant, magnesium coatings system with tailored properties” 7.US Air Force: “Cast Eglin Steel Development” NSF Bio-compatible Titanium Alloys Other Projects DARPA Modeling of Ti-6Al-4V for Additive Manufacturing Finite temperature predictions Phonon dispersions, band structures, etc. Phonon Perturbations S(T) and C p (T) CALPHAD Phase Description G=A+BT+CTlnT+DT 2 +ET -1 CALPHAD Phase Description G=A+BT+CTlnT+DT 2 +ET -1 Formation Energy Δ f H=E AB -E A -E B Formation Energy Δ f H=E AB -E A -E B First-principles calculations are used to predict thermochemical properties of phases where experimental data is not available *V. L. Moruzzi, J. F. Janak, and K. Schwarz, Phys. Rev. B 37, 790 (1988). VASP: PAW PBE-GGA ATAT ThermoCalc GGA+U Modeling across length scales Current projects Input: Crystal Structure VASP Output: Electronic structure Thermo-Calc Output: Phase diagram YPHON Calculate: Thermo- dynamic Properties Zhong, CALPHAD, 2005 Arroyave, PRB, 2006 Computational Materials System Design Prof. Zi-Kui Liu Prof. Zi-Kui Liu Current biomedical prosthetic devices used especially in knee and hip replacements have a higher elastic modulus than that of bone. Collaborators E V www.intechopen.com Li-ion rechargeable batteries are key constituent for high- energy-density storages needed for applications such as electronic devices. In this project we investigate a new class of Li- and Mn-rich layered cathode material residing in a multi-component space of xLi 2 MnO 3 ∙(1-x)LiMO 2 with M being Cr, Mn, Fe, Co and Ni. By using first-principles calculations the effects of these alloying elements are studied and potential outliers are searched for. In combination to calculations, cathode materials are synthesized and characterized within the collaboration with the Dept. of Mechanical and Nuclear Engineering. This can often lead to “stress shielding,” a key mechanism of implant failure. The project focuses on alloying titanium, which already has a relatively low elastic modulus, with other bio-compatible elements Mo, Nb, Sn, Ta, Zr to be able to match the elastic modulus of bone. By modeling the thermodynamic behaviors and elastic constants we hope to accelerate the design of this family of alloys. Fedotov, Phys. Met. Metall., 1985; Zhou, Mat Sci Eng A, 2004; Zhou, Mater Sci+, 2009; Zhou, Matser T, 2007; NSF High Energy Density Cathodes for Li-ion Batteries Additive manufacturing (AM) has enabled unprecedented control over the design of bulk alloys. A significant challenge associated with producing parts by laser-based AM methods is that a part's thermal history is a complex function of material properties, process parameters and part geometry. In this project thermodynamic and kinetic models are developed and used to predict the metastable phase compositions that occur during the additive manufacture of Ti-6Al-4V. These models will also be extended to compositionally-graded (gradient) alloys.