Accession Number : AD0633722

Title :   MECHANICAL PROPERTIES OF TANTALUM SINGLE CRYSTALS,

Corporate Author : CASE INST OF TECH CLEVELAND OHIO

Personal Author(s) : Spitzig,W. A. ; Mitchell,T. E.

Report Date : 1965

Pagination or Media Count : 263

Abstract : Three-stage hardening has been found to occur in tantalum single crystals deformed in tension over a limited range of orientations, temperatures and strain-rates. The orientation range is for crystals oriented favorably for single glide. The temperature range corresponds to T/Tm and equal to or about 0.10 to 0.18. The work-hardening rate in stage II is about G/600. The dislocation structure in tantalum single crystals exhibiting three-stage hardening has been investigated by transmission electron microscopy. In stage I tangles of dislocations containing many straight screw dislocations are seen lying parallel to the slip plane. In stage II an elongated cell structure develops with tangles of dislocations increasing in density and becoming linked together. Misorientations across cell boundaries become increasingly apparent with increasing deformation in stages II and III. A quantitative theory of work-hardening is presented for stage II in body-centered cubic metals which is an adaptation of a recent theory proposed by Hirsch. (Author)

Descriptors :   (*TANTALUM, *SINGLE CRYSTALS), MECHANICAL PROPERTIES, HARDENING, CRYSTAL DEFECTS, DEFORMATION, ELECTRON MICROSCOPY, STRAIN(MECHANICS), STRESSES

Subject Categories : Metallurgy and Metallography
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE