Strength, thermal defects, and solid solution hardening in nickel-containing B2 iron aluminides
- Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
- Univ. of New South Wales, Sydney, New South Wales (Australia). School of Materials Science and Engineering
- Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering
Nickel-containing ternary iron aluminides with an aluminum concentration of 45 at.% were investigated with respect to room temperature strength, equilibrium vacancy concentration, and the kinetics of vacancy removal. As compared to binary iron aluminides with the same Al concentration, nickel additions reduce the thermal equilibrium vacancy concentration at 1,273 K, whereas they increase this concentration at 973 K. Furthermore, at low temperatures such as 673 K, nickel additions increase dramatically the time needed to reach vacancy equilibrium. During prolonged annealing at 673 K, the density of <001> dislocations in Fe-45Al-3Ni (at.%) increased by an order of magnitude. This suggests that dislocations act as sinks for vacancies. At the same time, the number density of small (20--50 nm) voids decreased, indicating that they were not stable in the absence of substantial vacancy supersaturations. The findings show also that the solid solution strengthening of iron aluminides due to Ni is much weaker than previously thought.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 432988
- Report Number(s):
- CONF-961202--60; ON: DE97002633
- Country of Publication:
- United States
- Language:
- English
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