Phase stability, point defects and site preference of FeAl and NiAl with ternary additions

Technical Report · Sat Dec 31 04:00:00 EST 1994

OSTI ID:52827

Fu, C L; Zou, J ^[1]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

First-principles calculations have been used to investigate the defect properties and the site preference of FeAl and NiAl with ternary additions. It is found that a ``triple-defect`` structure model becomes invalid in describing the defect structure of FeAl (which is weakly ordered). The calculated mono-vacancy concentration on the Fe sites is lower than available experimental values by an order of magnitude, which may suggest the formation of defect complexes or the need of sufficiently long annealing time to anneal out quenched-in vacancies. For the site preference of ternary additions in FeAl, Cr and Ti are found to occupy Al sublattices, whereas Ni has a distinct preference for the Fe sites. The substitutional behavior of ternary elements in FeAl is consistent with the trend in the calculated heat-of-formation. For Fe addition in Al-rich NiAl, Fe atoms occupy Ni sublattices exclusively. The site preference of Fe addition in Ni-rich NiAl is dependent on alloy composition and temperature. At low temperatures, Fe atoms are found to preferentially occupy Al sublattices in Ni-rich alloys.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 52827
• Report Number(s): CONF-941144--141; ON: DE95009694
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CALCULATION METHODS
CHROMIUM ADDITIONS
CRYSTAL STRUCTURE
INTERMETALLIC COMPOUNDS
IRON ADDITIONS
IRON ALLOYS
NICKEL ADDITIONS
NICKEL ALLOYS
THEORETICAL DATA
TITANIUM ADDITIONS