Site Preference of Ternary Additions in Ni3Si

AbstractThe site preference of Al and elements in the 3rd row of the periodic table in Ni3Si was studied in a systematic way by using electronic structure calculations based on the local density approximation. Alloying elements in this intermetallic may occupy exclusively the Ni or Si sublattices, or may exhibit no particular site preference. By performing the calculations both for spin-polarized and non-spin-polarized cases, it was found that magnetism affects the computed site substitution behavior of Mn, Fe, and Co in Ni3Si. In the case of Fe, e.g., a preference for the Ni sublattice is computed when magnetic effects are ignored, but when magnetic effects are accounted for it is found that Fe has no significant site preference Specific trends regarding the site preference across the transition metal series are shown and discussed.

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Site Preference of Ternary Additions in Ni3A1

MRS Proceedings ◽

10.1557/proc-364-327 ◽

1994 ◽

Vol 364 ◽

Author(s):

M. Sluiter ◽

M. Takahashi ◽

Y. Kawazoe

Keyword(s):

Electronic Structure ◽

Local Density ◽

Electronic Structure Calculations ◽

Alloying Elements ◽

Site Preference ◽

Density Approximation ◽

Magnetic Effects ◽

Spin Polarized ◽

Ternary Additions ◽

Structure Calculations

AbstractThe site preference of a large number of alloying elements in Ni3AI (γ′) was studied in a systematic way by using electronic structure calculations based on the local density approximation. Alloying elements in this intermetallic may occupy exclusively the Ni or Al sublattices, or may exhibit no particular site preference. By performing the calculations both for spin-polarized and non-spin-polarized cases, it was found that magnetism strongly affects the computed site substitution behavior of Mn, Fe, and Co in Ni3Al. In the case of Fe, for example, a preference for the Ni sublattice is computed when magnetic effects are ignored, but when magnetic effects are accounted for it is found that Fe has no significant site preference, in much better agreement with a large number of experimental determinations. Some trends regarding the site preference across the periodic table are shown and discussed.

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Phase Stability and Site Substitution in NB-AL Compounds

MRS Proceedings ◽

10.1557/proc-364-1111 ◽

1994 ◽

Vol 364 ◽

Author(s):

M. Sluiter ◽

M. Takahashi ◽

Y. Kawazoe

Keyword(s):

Electronic Structure ◽

Phase Stability ◽

Local Density ◽

Electronic Structure Calculations ◽

Site Preference ◽

Density Approximation ◽

Atomic Order ◽

Σ Phase ◽

Site Preferences ◽

Structure Calculations

AbstractThe site preferences of Ta, Mo, and W in A15 Nb3Al, the phase stability of off-stoichiometric A15 Nb3Al, and the atomic order of the Nb2Al D8b (σ) phase are investigated by performing electronic structure calculations based on the local density approximation. Mo, W, and Ta are found to have a preference for the Nb sublattice. Ta has the strongest site preference. It was shown that some recently proposed ground states for off-stoichiometric A15 phases are unlikely to occur in the Nb-Al system. Moreover, it was shown that the atomic order in the D8b Nb2Al phase contributes significantly to its stability.

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ON THE PREDICTION OF FERROMAGNETISM AND METAMAGNETISM IN 4d TRANSITION-METAL OVERLAYERS

Modern Physics Letters B ◽

10.1142/s0217984992000703 ◽

1992 ◽

Vol 06 (11) ◽

pp. 605-615 ◽

Cited By ~ 1

Author(s):

OLLE ERIKSSON ◽

R. C. ALBERS ◽

A. M. BORING ◽

G. W. FERNANDO ◽

B. R. COOPER

Keyword(s):

Electronic Structure ◽

Transition Metal ◽

Electronic Structure Calculations ◽

Local Spin Density Approximation ◽

Spin States ◽

Density Approximation ◽

Spin Polarized ◽

Theoretical Evidence ◽

Metal Overlayers ◽

Structure Calculations

We present theoretical evidence for ferromagnetism in Ru and Rh overlayers on Ag(001). These predictions are based on ab-initio, spin-polarized, electronic-structure calculations within the framework of the local spin-density approximation. For Tc, Ru, Rh and Pd overlayers chemisorbed on Ag(001), only Ru and Rh exhibited ferromagnetism. Several metamagnetic spin states were found for the Ru overlayers.

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Effects of ternary additions on the twin energy and site preference in γ-TiAl

Journal of Materials Research ◽

10.1557/jmr.1994.1755 ◽

1994 ◽

Vol 9 (7) ◽

pp. 1755-1760 ◽

Cited By ~ 13

Author(s):

Jian-hua Xu ◽

A.J. Freeman

Keyword(s):

Total Energy ◽

Local Density Approximation ◽

Relative Stability ◽

Local Density ◽

Site Preference ◽

Density Approximation ◽

Self Consistent ◽

Ternary Additions

Site preference and the effects of ternary additions (Mn, V, etc.) on the twin energy in γ-TiAl were studied by means of all-electron total energy self-consistent calculations based on the local density approximation. The results show that when Mn, Ti, or V substitute on the Al-sites in γ-TiAl, the twin energy is about 20–25% lower than that of stoichiometric γ-TiAl; this may explain observations of increased twinning activity in 48% Al TiAl. By contrast, when ternary additions of V (or Al) occupy Ti-sites, the twin energy has nearly the same value as that of pure γ-TiAl, which is consistent with the observation of only a few twins for Al-rich compositions. By comparing the total energy of Ti6(XAl5) and (Ti5X)Al6 supercells, it is found that the relative stability of Ti6(XAl5) over (Ti5X)Al6 (i.e., the preference for occupying Al-sites) is increased in going from Nb, V, Cr, and Ti to Mn, in agreement with observation that excess Ti occupies Al-sites, and Nb preferentially substitutes on the Ti-sites. The results indicate that Mn preferentially substitutes on the Al-sites, and V (or Cr) may occupy both Ti- and Al-sites.

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