Akademik Məlumat İdarəetmə Sistemi
Acta Materialia, vol.47, no.7, pp.2067-2075, 1999 (SCI-Expanded, Scopus)
The energetic and structural characteristics of atomic ordering processes in Fe0.5(Al1-nXn)0.5 intermetallics have been qualitatively analyzed based on the statistico-thermodynamical theory of ordering by means of a quasi-chemical method combined with electronic theory in the pseudopotential approximation. The effects of ternary impurities on order-disorder phase transformation temperature and the characteristics of atomic short-range order in Fe-Al type intermetallics have been calculated. Impurity elements in Fe0.5(Al1-nXn)0.5 where X = Ni, Co, Mn, Cr, Ti, Si, Zr, Hf, Nb, Ta, Re, Mo or W, are considered up to 1 at.% concentration. The results of the calculation indicate that the impurity elements, X, with regard to their lattice site occupancy characteristics (SRO) can be divided into two groups; XI = Ni, Co, Mn or Cr element atoms substitute mainly for Al sublattice sites, whereas XII = Ti, Si, Zr, Hf, Nb, Ta, Re, Mo or W element atoms substitute preferentially for Fe sublattice sites in Fe0.5(Al1-nXn)0.5 intermetallics. It has been found that the absolute values of partial ordering energies of the WAl-X(R1) and WFe-X(R1) have a profound effect on the order-disorder transition temperature of Fe0.5(Al1-nXn)0.5 alloys that would either increase or remain unchanged depending on the type and content of the ternary substitutional alloying elements. The impurities X = Zr, Hf, Nb, Ta, Re, Mo or W which are preferentially distributed Fe sublattice sites are more effective in increasing order-disorder transition temperature in Fe-Al(B2) intermetallics. The results of the present calculation are in good qualitative agreement with experimental observation for most of the third component impurity elements X in Fe0.5(Al1-nXn)0.5 intermetallics.