Accession Number : AD0607258

Title :   RECOVERY BEHAVIOR OF PURE ALUMINUM AND SELECTED BODY-CENTERED CUBIC METALS.

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

Corporate Author : LOCKHEED MISSILES AND SPACE CO SUNNYVALE CALIF

Personal Author(s) : Lytton,J. L. ; Westmacott,K. H. ; Potter,L. C.

Report Date : AUG 1964

Pagination or Media Count : 64

Abstract : The flow stress recovery of high-purity aluminum, unalloyed sintered molybdenum, Mo-1 wt % W, and electron-beam-melted columbium following a tensile prestrain was studied in terms of a fractional flow stress recovery parameter f. The flow stress recovery behavior was related to the dislocation rearrangements using transmission electron microscopy for aluminum and columbium and etch-pit techniques for molybdenum. During recovery of aluminum at 120C and 160C, nearly stable strength levels were attained, the strength level for 120C recovery being greater than that for 160C. This stabilization of flow stress was related to the formation of metastable dislocation networks bounding nearly perfect cells. The recovery of molybdenum and Mo-1 wt % W was studied at 800 and 900C, and the results showed that the tungsten addition had no effect on the recovery behavior. An etch-pit study of the dislocation substructures formed at 900C revealed that recovery was accompanied by the formation of subboundaries along certain lattice planes to form approximately square cells when viewed in the sheet plane. The recovery of columbium was studied at 800 and 900C. The flow stress decreased and then increased after reaching a minimum, especially at 900C. Network formation was shown to occur, and the observed increase of flow stress with increasing recovery time was related to the formation of a precipitate along dislocation lines.

Descriptors :   (*ALUMINUM, SHEAR STRESSES), (*MOLYBDENUM, SHEAR STRESSES), (*NIOBIUM, SHEAR STRESSES), MOLYBDENUM ALLOYS, TUNGSTEN ALLOYS, STRESSES, ELECTRON MICROSCOPY, METALLOGRAPHY, CRYSTAL SUBSTRUCTURE, CRYSTAL DEFECTS, DEFORMATION, GRAIN BOUNDARIES, HIGH TEMPERATURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE