Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

State and habit of the Fe/sub 16/N/sub 2/ precipitate in b. c. c. iron: elastic theory

Journal Article · · Acta Metall.; (United States)
The linear elastic theory is used to determine the preferred habit of the ..cap alpha../sup 2/ Fe/sub 16/N/sub 2/ precipitate in ..cap alpha.. iron, assuming that the precipitate is a coherent, tetragonal phase having the form of a thin circular disc, and neglecting both surface tension effects and the difference in elastic constants between the precipitate and the iron matrix. With these approximations the precipitate habit depends on the tetragonality of the transformation strain connecting the matrix and precipitate lattices, the aspect ratio of the disc, and the elastic constants. The preferred habit of Fe/sub 16/N/sub 2/ in ..cap alpha.. iron is found to vary with the precipitate aspect ratio (K). The preferred habit changes continuously from (100) for K < 11.35 to an asymptote near (102) for large values of K. The results can explain the common (100) habit of Fe/sub 16/N/sub 2/, but predict that this habit is unstable when the precipitate aspect ratio is large. The theory is also used to calculate the lattice parameters of the precipitate when it is constrained within ..cap alpha.. iron. The results agree with experimental data and provide a simple explanation for discrepancies in the reported values of the lattice parameters of Fe/sub 16/N/sub 2/. 22 references, 5 figures.
Research Organization:
Univ. of California, Berkeley
DOE Contract Number:
AC03-76SF00098
OSTI ID:
5541395
Journal Information:
Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 32:2; ISSN AMETA
Country of Publication:
United States
Language:
English