The Structural Metallic Materials Group at Northwestern University, supervised by Prof. David C. Dunand, focuses on the mechanical behavior of metallic alloys, composites and foams/microlattices. Concurrent research also addresses advanced processing techniques (e.g., to fabricate novel composites and foams) and microstructure characterization (e.g., to link the observed microstructure to the measured mechanical properties).

[View Completed Projects]

Additive Manufacturing of Alloys

*recently completed project/researcher graduated

Selective laser melting

Oxide Dispersion Strengthened Superalloys

Jennie Glerum and Dr. Christoph Kenel; co-advised by Dr. Jonathan Almer

We are investigating aluminum ODS alloys: first alumina dispersoids in a pure aluminum matrix, and then alumina and yttria dispersoids in an Al-Sc matrix capable of Al3Sc precipitation in solid state.

Near eutectic Al-Ce alloys

Tiffany Wu, co-advised by Dr. Alex Plotkowski and Dr. Ryan Dehoff, Oak Ridge National Laboratory

Near eutectic Al-Ce alloys cast in bulk form show good strength and ductility. Our research focus on these alloys manufactured via selective laser melting and containing ternary and quaternary alloying additions. Preliminary research done at ORNL has showed promising strengths in eutectic Al-Ce-TM system, whose microstructures and mechanical properties (including creep) are being investigated

3D ink printing/sintering

Metals and alloys

Chun-Te Wu and Dr. Christoph Kenel

3D ink extrusion printing is studied as an emerging processing technique to fabricate metals and complex alloys from pre-alloyed, elemental or compound powders. Combining different oxides or hydrides allows to create alloys directly from blended feedstock, further reducing the costs and risks related to fine metal powders typically used in beam-based AM.

Ceramics and composites

Dingchang Zhang, Simon Moser, Dr. Christoph Kenel, *Pengyu Chen, *Prof. Binna Song, *Jens Sesseg, and *Micha Calvo

3D-extrusion ink-printing combines the formulation and 3D deposition of an extrudable ink containing metal, ceramic or composite powders with an isothermal sintering step. This allows to process brittle alloys, ceramics and composites that cannot be processed by beam-based AM

Freeze-Casting of Metals and Ceramics

*recently completed project/researcher graduated

Freeze-Casting of Iron Foams for Iron-Air Batteries

Stephen Wilke, Jacob Mack, *Pedro Javier Lloreda Juardo, *Teakyung Um, *Robert Lundberg, and *Amelia Plunk

We are investigating freeze casting to create iron foams with various pore morphologies designed to improve the lifetime of materials used in high-temperature redox processes, like iron-air batteries and chemical looping combustion. We are using in operando X-ray microtomography to study the evolution of structure, porosity, and extent of reaction in freeze-cast, lamellar iron foams during redox cycling.

Microstructural Evolution in Freeze-Cast Materials

Kristen Scotti, Cristabella Wolff, and Jacob Mack; co-advised by Prof. Peter Voorhees

As part of NASA's Materials Lab Open Science Campaign, directional solidification experiments will be conducted on the International Space Station, and freeze-casted samples will be sent back to Northwestern University for microstructural investigation. The aim of this work is to produce benchmark data necessary to advance the freeze-casting technology for both terrestrial and space-based materials processing, including producing data applicable for testing three existing freeze-casting models.

Ice-templating of TiO2

Kristen Scotti, Pierce Pettit, *Emily Northard, *Amelia Plunk, *Lauren Kearney, *Jared Burns, and *Matthew Ocana

We are using aqueous suspensions of titanium dioxide as a model suspension system to study the effect of gravity on microstructures templated during directional solidification of ice-templated materials. We previously conducted experiments on reduced gravity parabolic flights and investigated the effect of solidification direction under normal terrestrial gravity; currently, we are investigating the effect of water's density inversion at 4 °C on TiO2 microstructures.

SpaceICE ("Interface Convective Effects") CubeSat Mission

Kristen Scotti, Chelsea Ye, Lawrence Luo, Bohan Yao, *Dominic Herincx, *Jessica Li, *Robert Lundberg, *Teddy Broeren, *Andy McIntosh, *Lauren Kearney, and in collaboration with University of Illinois at Urbana-Champaign

In partnership with the University of Illinois, Urbana-Champaign and Bradley University, directional solidification experiments will be conducted on a CubeSat (a small satellite that orbits Earth); the satellite will is expected to launch with NASA's CubeSat Launch Initiative in 2022.

*Freeze-Casting of Silicon

*Fernando Reyes

We are working to develop and establish the freeze-casting process for silicon foams for battery applications.

High Temperature Superalloys

*recently completed project/researcher graduated

Aluminum-based superalloys

Dr. Amir R. Farkoosh, Dan Rosenthal, *Dr. Shipeng Shu, *Dr. Jacques Perrin Toinin, *Dr. Anthony De Luca, *Dr. Dinc Erdeniz, *Richard Michi, *Chanun Suwanpreecha, and *Dr. Nhon Q Vo; in collaboration with Prof. David Seidman

We investigate microstructure and creep properties of binary and ternary Al-Sc-X, Al-Ti-X and Al-Zr-X alloys with nanoscale, coherent, coarsening-resistant precipitates. Additions of submicron alumina dispersoids are also investigated.

Cobalt-based superalloys

Dr. Fei Xue, Brandon Ohl, *Dr. Jacques Perrin Toinin, *Tony Chung, *Fernando Reyes, *Francesca Long, *Chunan Li, *Hyeji Park, *Dr. James Coakley, *Dr. Peter Bocchini, and *Dr. Daniel Sauza; in collaboration with Prof. David Seidman

We are developing new high temperature alloys based on Cobalt. Methods such as creep and hardness tests are used to investigate the mechanical properties of these alloys and Atom Probe Tomography is utilized to study the structure.

Creep-Resistant Alloys

*recently completed project/researcher graduated

Creep of Thermoelectric Materials

Muath Mohammed Al Malki, co-advised by Prof. Jeffrey Snyder

We are exploring the relationship between creep deformation (during operation at stress and temperature) and thermoelectric performance degradation for various thermoelectric alloys.

Al-Ce Creep Resistant Alloys

Tiffany Wu, *Yang Liu and *Daniel Ng

Our work involves microstructural investigations and compression creep testing of Al-Ce binary alloys, with the goal of studying how Ce additions may be utilized to develop alloys with enhanced creep resistance.

Metallic Foams

*recently completed project/researcher graduated

Bulk nanostructured metals from twinned silver nanowires

Luke Prestowitz, co-advised by Prof. Jiaxing Huang

Collaborating with the Huang lab, we are building a bulk nanostructured material from silver nanowires. We use multiply-twinned nanowires, assembled into a green body, to discover new metallic materials with exceptional properties and microstructures.

Hollow Nickel-Based Alloy Micro-Tubes via Directed Kirkendall Pore Formation

Dr. Alex Chadwick, *Dr. Dinc Erdeniz, *Dr. Ashley Paz y Puente, and *Aaron Yost, in collaboration with Prof. Ashley Paz y Puente, University of Cincinnati

Typically, Kirkendall pores are considered detrimental because they deteriorate the mechanical, thermal, and electrical properties of materials, but we focus on the use of the Kirkendall effect as a novel route for the fabrication of β-NiAl(Cr) and shape memory NiTi microtubes.

Manufacturing of Aluminum foam

Youngseok Song, co-advised by Prof. Heeman Choe at Kookmin University

New project; description coming soon!

Synchrotron X-ray Tomography and Diffraction

*recently completed project/researcher graduated

Reduction and Sintering of Freeze-Cast Oxides to Create Metallic Foams

Stephen Wilke, Jacob Mack, and *Pedro Javier Lloreda Juardo

Metal foams created by freeze casting are typically prepared from oxide precursor powders, which are reduced and sintered at high temperature in the final processing step. We are using in situ X-ray microtomography to investigate the structural changes of the oxide green bodies as they are reduced and sintered to metal.

Cultural Heritage Materials

*recently completed project/researcher graduated

Investigation of Archeological Slag

Kathleen Dewan and Kristen Scotti, in collaboration with Prof. Marc Walton, Center for Scientific Studies in the Arts

Tell Atchana ("Alalakh") is an ancient city located in present-day Turkey that was occupied from the late-Early Bronze Age into the Iron Age. We are investigating slag specimens uncovered from craft quarters within this city by an excavation team led by Prof. Kutlu Aslihan Yener (University of Chicago). Here, we are attempting to reconstruct the life-cycle of these specimens in an effort to better understand the manufacturing processes that were used at Alalakh.