Accession Number : AD0610468

Title :   STUDY OF LOCAL-ORDER AND SOLID-SOLUTION STRENGTHENING IN COLUMBIUM ALLOYS.

Descriptive Note : Rept. for 1 May 63-30 Apr 64,

Corporate Author : BATTELLE MEMORIAL INST COLUMBUS OHIO

Personal Author(s) : Rudman,P. S.

Report Date : 22 JAN 1965

Pagination or Media Count : 37

Abstract : This research program attempted to establish whether Fisher's 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.

Descriptors :   (*NIOBIUM ALLOYS, HARDENING), (*VANADIUM ALLOYS, HARDENING), SOLID SOLUTIONS, CRYSTAL LATTICES, X RAY DIFFRACTION, SCATTERING, TITANIUM ALLOYS, MOLYBDENUM ALLOYS, TUNGSTEN ALLOYS, DIFFUSION, PHASE STUDIES, THEORY, MATHEMATICAL MODELS

Distribution Statement : APPROVED FOR PUBLIC RELEASE