Dislocation sources in ordered intermetallics
- Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
- GKSS-Research Centre, Geesthacht (Germany). Inst. for Materials Research
- Technical Univ. Hamburg-Harburg, Hamburg (Germany)
An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Alexander von Humboldt-Stiftung, Bonn (Germany)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 373933
- Report Number(s):
- CONF-961017--6; ON: DE96015049
- Country of Publication:
- United States
- Language:
- English
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