Structure/Property Relationships in High Strength Nanostructured Spinodal FeNiMnAl Alloys

Funded by the Department of Energy

The objective of this project is to understand the microstructure and deformation mechanisms controlling the strength and ductility in a range of recently-discovered, very high strength, FeNiMnAl spinodal alloys, and to model their mechanical behavior either by using existing theoretical models or, more likely, by developing a new model. The work involves

  1. Determining the critical resolved shear stress of single crystals of several FeNiMnAl spinodal alloys aged for various times at different temperatures.
  2. Microstructural characterization of the as-cast and aged alloys using a combination of state-of-the-art techniques and instruments including: x-ray diffraction using a rotating anode X-ray set; a field emission gun (FEG) transmission electron microscope (TEM) with convergent beam electron diffraction (CBED) and energy dispersive x-ray spectroscopy (EDS); a high resolution (HR) TEM; a FEG HR scanning transmission electron microscope (STEM) with CBED and EDS; and a Local Electrode Atom Probe (LEAP). These will provide information on the crystal structures, lattice parameters, coherency strains, interface structure, and wavelength and amplitude of the spinodally-decomposed phases.
  3. Determining the deformation mechanisms of the alloys after different ageing treatments using: slip line analysis using a FEG scanning electron microscope (SEM); post-mortem TEM dislocation analysis; and TEM in-situ straining studies.
  4. Using the above results to evaluate existing models of strengthening in spinodal alloys in a more thorough and comprehensive fashion than previously attempted, and, if necessary (as is likely), developing a new model based on the experimentally-observed deformation mechanisms.

The project involves collaboration with Drs. M.K. Miller, K. More and A. Payzant at the Oak Ridge National Laboratory through the SHaRE program, and Dr. R. Zhang and Prof. S. Ringer at the University of Sydney, Australia through the AMMRF-TAP program.