Category:Research

From Northwestern University Center for Atom-Probe Tomography
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Atomic reconstruction of an MgO ceramic precipitate in a Cu metal matrix (the matrix atoms are omitted for the sake of clarity). From J. Ruesing, J. T. Sebastian, O. C. Hellman, and D. N. Seidman, "Three-Dimensional Investigations of Ceramic/Metal Heterophase Interfaces by Atom-Probe Microscopy," Microscopy and Microanalysis 6, 445-451 (2000). Data collected using the 3DAP and rendered using Apex.

We are interested in understanding physical and mechanical phenomena associated with internal interfaces, e.g., interfacial energies, segregation, phase transformations, and creep. In addition to interfacial properties, we are studying the temporal evolution of microstructures. Materials systems studied include multiphase and multicomponent metallic alloys (model Ni-base superalloys, and Al-Sc- and Ti-Al-based alloys) and ceramic/metal heterostructures (e.g. MgO/Cu, Al2O3/Nb, TiAl/carbides and MoN/Fe ). Experimental methods employed for the characterization of both structure and chemistry on a nanometer scale are high-resolution electron, analytical electron and three-dimensional atom-probe (one of three in the States) microscopies. In parallel with the experiments we are studying the same systems on the same length scales by a variety of computer simulation techniques. Specifically kinetic Monte Carlo simulation is used to study precipitation of the gamma prime phase in nickel-base superalloys and the Al3Sc intermetallic in Al(Sc) based alloys. First-principles local-density-functional theory methods are also employed to predict interfacial properties of ceramic/metal interfaces.

Some of our research can be seen in nuggets.

Research Topics: Ceramic/Metal Interfaces, High Temperature Aluminum Alloys, Kinetic Monte Carlo Simulations, Magnetic Multilayers, Nanoscale Precipitation-Strengthened Steels, Ni-Based Superalloys, Semiconducting Materials