Density Functional Theory

HΨ = EΨ

E-V curveE0 V0 B B’

International Travel

Wha

t w

e 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”

NSFBio-compatible Titanium Alloys

Other Projects

DARPAModeling of Ti-6Al-4V for Additive Manufacturing

Finite temperature predictions

Phonon dispersions, band structures, etc.

Phonon Perturbations

S(T) and Cp(T)

CALPHAD Phase DescriptionG=A+BT+CTlnT+DT2+ET-1

Formation EnergyΔfH=EAB-EA-EB

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

G T,V F0K V Fion T,V PV

GGA+U

Modeling across length scales

Curr

ent

proj

ects

Input: Crystal Structure

VASP

Output: Electronic structure

Thermo-Calc

Output: Phase diagram

YPHON

Calculate: Thermo-dynamic PropertiesZhong, CALPHAD, 2005

Arroyave, PRB, 2006

Computational Materials System Design 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 xLi2MnO3∙(1-x)LiMO2 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.

Ti TaWt. % Ta

Youn

g’s

Mod

ulus

, GPa

α (hcp)

β (bcc)1

2

186 GPa

bcc

hcp

bcc

-60

-20

20

60

100

140

180

220

0 20 40 60 80 100

Fedotov et al. (Expt.) Zhou et al. (Expt.) Ikehata et al. (Calc.) Wu et al. (Calc.)Shang et al. (Calc.)

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;

NSFHigh 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 andkinetic models are developed and used to predict the metastable phasecompositions that occur during the additive manufacture of Ti-6Al-4V. These models will also be extended to compositionally-graded (gradient) alloys.