Defects and the functionality of metallic structural thin films

20130927_H242-R4-s1_650C-24h_AFRL(Ar)_005_bf_67kx-property-processing relationships are at the heart of traditional materials science and engineering.  In the field of metallurgy, careful refinement of these parameters over many decades have lead to many high performance alloys that can operate at high homologous temperatures, under severe corrosive conditions and extreme mechanical loads.  As the scale of these structural alloys shrinks for applications including microelectromechanical systems (MEMS) and protective coatings, we are working to expand our understanding of fundamental relationships between the nonequilibrium microstructures, which are typical of films/structures at this scale, and the evolution of film properties.  This work involves thin film processing, shaping and characterization using sputtering methods, current assisted densification schemes, electron microscopy and particularly small-scale mechanical characterization techniques.

Deformation mechanisms in high performance ceramics

Ferroelastic toughening is an important yet elusive deformation mechanism in conventional thermal barrier coatings based on yttria stabilized zirconia.  This mechanism, dependent on crystal symmetry, is also present in many electroceramics systems.  The pheonomenon itself was identified many decades ago; Ferroelastic twinning in Ce,Ti-stabilized zirconia.tiffhowever, we still lack a fundamental understanding of the controlling parameters necessary to effectively design tougher ceramics.  We are striving to understand how microstructural effects such as grain size, orientation and phase constituency may impact the activation of ferroelasticity.  To do this, we are using advanced microscopy techniques including electron backscatter diffraction, nanodiffraction, and small-scale mechanical cyclic loading configurations.

Development of Novel Surfaces to Mitigate Carbonaceous Deposits on Structural Alloys

Deposition of carbonaceous materials during extraction, refinement or use of oil onto structural alloys is a tricky, yet critical challenge to the continued safe use of oil products. We are developing novel surface modifications to conventional structural alloys that may reduce these depositions.



Dynamic structural evolution in extreme gradients

15min_composite+HRWhen we think of energy and materials batteries and photovoltaics are often the first to come to mind. What about the advanced materials suite that enablecurrent energy production routes?  How can improved materials durability or functionality lead to more efficient gas turbine engines or more reliable nuclear reactors?  In this group we are studying the evolution of mechanical properties as a function of phase and microstructural evolution under thermal gradients for protective coatings and other structural materials.