Abstract

MKHONTO, C.S.; CHAUKE, H.R.  and  NGOEPE, P.E.. First-principles studies of Fe-Al-X (X = Pt, Ru) alloys. J. S. Afr. Inst. Min. Metall. [online]. 2017, vol.117, n.10, pp.963-967. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2017/v117n10a6.

The Fe-Al based alloys have recently attracted a lot of attention due to their excellent resistance to oxidation at high temperatures. However, they suffer limited room temperature ductility and a sharp drop in strength above 600°C. The current study employed a density functional theory approach to investigate the stability of FeAl-X alloys. We employed virtual crystal approximation to model various atomic concentrations (0 s X <5) of both Pt and Ru; this will allow more precise predictions on the materials' behaviour. Density of states was used to describe the behaviour of each phase near the Fermi level; these phases were observed at different percentage compositions. The FeAl composition is most favourable since it displays positive shear moduli, condition of mechanical stability. Addition of Pt and Ru was found to significantly improve the ductility of the Fe-Al-X compound for 0.2 and 0.5 at.% compositions, respectively.

Keywords : FeAl-X alloys; DFT; heats of formation; thermodynamic stability; density of states; elastic constants; X-ray diffraction patterns.

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