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Ab initio determined materials-design limits
Combining Experimental and Computational Methods in the Development of Fe3Al-based Materials
Ab initio based description of the stacking fault properties in high-Mn steels
Chemical trends for hydrogen in metals
Theoretical study of Strain Effects on ELNES and Electronic structure of AlGaN alloys
Ab-initio based growth simulations of III-Nitride nanostructures
Grain Boundary dynamics from atomistic calculations
Third order elastic constants of III-Nitride alloys
Electric activity of charged dislocations in GaN
Band alignment of ScN and GaN semiconductors
Growth simulations of thermodynamically highly unstable nitride based alloys
Influence of defects on the energetics and dynamics of hydrogen in manganese steels
Ab initio up to the melting point
Ab initio calculation of magnetic excitations
Multi-physics modeling of strain-induced interactions in interstitial solid solutions
Multiscale Library S/PHI/nX
Continuum models to investigate optical properties of semiconductor nanostructures
First-principles studies of hydrogen in metals
Ab initio study of corrosion: Adsorbate phases on surfaces and phase diagrams
First-principles study of Fe-Al alloys
Phase stability and mechanical properties of biocompatible Ti-alloys
Ab initio calculations of structural and magnetic phases of iron
First-Principles Study of the Carbon-Carbon Interaction in Iron
Solid-Solid Interfaces
Hydrogen in GaN-based LEDs
Atomistic calculations of the mechanical properties of chitin molecules
GW band alignment
Multiscale Simulations of Hydrogen embrittlement
Magnetic shape memory alloys
Defect structures and EPR parameters in Si-based solar cells
Ab initio study of polyelectrolyte/nanoclay interactions
Generation of optimal LCAO basis sets
EXX calculations for defects
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First-principles study of Fe-Al alloys

First-principles study of Fe-Al alloys

M. Friak. J. Neugebauer in cooperation with M. Palm and F. Stein

The project is a part of joint inter-departmental reserach activity at the Institute aimed at developing new lightweight Fe-Al based alloys.

Iron aluminides represent a promising class of intermetallics with great potential for substituting stainless steels for applications at elevated and high temperatures. Noteworthy in this respect is their excellent chemical resistance with respect to corrosion and sulfidation processes, low cost of the constituents, high strength, and a lower density compared to that of many other iron-based materials [1]. Previous attempts to further reduce the density of the Fe-Al-materials have been hampered by the fact that the dependence of the alloy composition as a function of the lattice constant is rather complex: several experimental studies observed an anomalous, strongly non-linear behavior over a large part of the composition range [2-3] (see the figure below). The study of the volume-composition dependence has been also complicated by the fact that the functional behavior of the dependence turned out to be not unique but to depend on the processing history (i.e. the thermal and mechanical treatment) of the sample studied (see the black and red symbols in the right-side graph in the figure below).

In order to to identify the origin of the observed anomaly the theoretical calculations of Fe-Al alloys with various compositions and local order employing density functional theory are performed. In this  theoretical study the focus is on the Fe-rich part of the Fe-Al phase diagram where all the structures are derived from the cubic body centered (bcc) structure of pure iron. As two examples,  the Fe3Al in the D03 structure and FeAl in the B2 lattice are shown in the left column in the figure above. The ab initio results are planned to be used to construct a cluster expansion [4] of the total energy, magnetic moment as well as equilibrium volume of the Fe-Al alloys in a cooperation with PD Dr. S. Mueller from the Universitaet Erlangen-Nuernberg.

References

  1. Deevi, S.C.; Sikka, V.K.; Intermetallics 4, 357 (1996).
  2. Taylor, A.; Jones, R.; J. Phys. Chem. Solids 6, 16 (1958).
  3. Palm, M.; PhD-thesis, Max-Planck-Institut fuer Eisenforschung, GmbH, Duesseldorf (1990).
  4. J. M. Sanchez, F. Ducastelle, D. Gratias, Physica A 128, 334 (1984).
This page is maintained by Martin Friak. Last update: 13.01.2009