Effect of ternary alloying elements addition on atomic ordering characteristics of Fe-Al intermetallics
- Middle East Technical Univ., Ankara (Turkey). Dept. of Metallurgical and Materials Engineering
The energetic and structural characteristics of atomic ordering processes in Fe{sub 0.5}(Al{sub 1{minus}n}X{sub n}){sub 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 Fe{sub 0.5}(Al{sub 1{minus}n}X{sub n}){sub 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: X{sub I} = Ni, Co, Mn or Cr element atoms substitute mainly for Al sublattice sites, whereas X{sub II} = Ti, Si, Zr, Hf, Nb, Ta, Re, Mo or W element atoms substitute preferentially for Fe sublattice sites in Fe{sub 0.5}(Al{sub 1{minus}n}X{sub n}){sub 0.5} intermetallics. It has been found that the absolute values of partial ordering energies of the W{sup Al-X}(R{sub 1}) and W{sup Fe-X}(R{sub 1}) have a profound effect on the order-disorder transition temperature of Fe{sub 0.5}(Al{sub 1{minus}n}X{sub n}){sub 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 Fe{sub 0.5}(Al{sub 1{minus}n}X{sub n}){sub 0.5} intermetallics.
- OSTI ID:
- 357925
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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