Accession Number : AD0633600

Title :   DEFORMATION STRUCTURES IN ZONE-MELTED MOLYBDENUM ABOVE ROOM TEMERATURE.

Descriptive Note : Interim rept.,

Corporate Author : FRANKLIN INST RESEARCH LABS PHILADELPHIA PA

Personal Author(s) : Lawley,A.

Report Date : SEP 1965

Pagination or Media Count : 30

Abstract : Stress-strain behavior of single crystal molybdenum oriented for slip on the (011) (111) slip system has been examined at 578K; the associated glide dislocation configurations have been characterized by thin film transmission electron microscopy. A high density of prismatic loops is observed elongated along (211). Few long segments of primary screw dislocation exist, but there are serrated, angular, and cusp-shaped segments of short length. The debris of dislocation loops has the same Burgers vector as the primary screw dislocations. Dislocation tangling is restricted to the immediate vicinity of inclusions or pinned grown-in dislocations. In comparison, the slip band structure in the range 4.2 - 300K is characterized by the presence of long primary screw dislocations of Burgers vector plus or minus a/2 (111). Jog formation at 578K is most likely the result of thermally activated cross-slip. However, it is possible that the magnitude of the dislocation uncertainty perpendicular to the slip plane in molybdenum at this temperature is sufficient to provide job heights consistent with the width of the observed elongated prismatic loops. The work-hardening level is controlled by the extent of secondary slip, and by the recovery occurring through cross-slip. (Author)

Descriptors :   (*MOLYBDENUM, *CRYSTAL DEFECTS), SINGLE CRYSTALS, STRESSES, STRAIN(MECHANICS), DEFORMATION, CRYSTAL SUBSTRUCTURE, ZONE MELTING

Subject Categories : Metallurgy and Metallography
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE