DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click HERE
to register or log in.
STUDY OF LOCAL-ORDER AND SOLID-SOLUTION STRENGTHENING IN COLUMBIUM ALLOYS.
BATTELLE MEMORIAL INST COLUMBUS OHIO
This research program attempted to establish whether Fishers local-order solution-strengthening mechanism is of importance in columbium-base alloys by correlating X-ray diffuse-scattering determinations of local order with mechanical properties. Results of the project indicated that local order can make a significant strengthening contribution, but other mechanisms can also dominate. By X-ray diffuse-scattering powder-pattern analysis, it has been determined that Cb-V alloys are nearly random. The atom-size effect was also determined, indicating there is a size accommodation in solution such that, instead of the 8.5 per cent size difference of the pure components, there is only about a 3 per cent difference. The results are discussed in terms of atom-size-accommodation mechanisms, ordering driving force, and solidsolution strengthening. Solid-solution strengthening due to atom-size difference in a substitutional binary alloy is shown to depend on composition fluctuations. An elastic model of binary solid solutions is extended to include short-range order SRO strain relaxation. It is shown that typically about half of the atom dilation and strain energy can be relaxed by SRO.
Rept. for 1 May 63-30 Apr 64,
AF33 657 8844