SUBSTRUCTURE AND MECHANICAL PROPERTIES OF REFRACTORY METALS

Technical Report · Sun Apr 01 04:00:00 EST 1962

OSTI ID:4776328

Lement, B S; Thomas, D A; Weissmann, S; Owen, W S; Hirsch, P B

Coordinated program on substructural characteristics of W, Mo, Ta, and Nb was carried out by ManLabs, M.I.T. Rutgers, U. Liverpool (Eng.) and U. Cambridge (Eng.) by means of advanced microscopic, x-ray diffraction, and mechanical testing techniques. Initial increase in hardness during recovery of heavily deformed W wire is ascribed to segregation of interstitials to dislocations and to microtwinning. Sharp drop in ductility on 1100 deg C anneal is attributed to rise in transition temperature to above room temperature due to increase in fiber width. Competing processes of polygonization and strain induced fiber boundary migration occur up to 1400 deg C. In Ta single crystals, the maximum principal strain changes from positive to negative on deforming below and above the upper yield point respectively. Binding energy between dislocations and interstitials in Ta is about 0.53 ev. For low interstitial contents, k/sub y/ increases as the dislocation density is decreased by higher annealing above recrystallization; for high interstitial contents, k/sub y/ is not affected. The activation energy for annealing-out of dislocation loops in Ta and Nb is about 3 ev. (auth)

• Research Organization: Manufacturing Labs., Inc., Cambridge, Mass.
• NSA Number: NSA-17-003499
• OSTI ID: 4776328
• Report Number(s): WADD-TR-61-181(Pt.II)
• Country of Publication: United States
• Language: English

Related Subjects

ANNEALING
BINDING ENERGY
CONFIGURATION
DEFECTS
DEFORMATION
DIFFRACTION
DISLOCATIONS
DISTRIBUTION
DUCTILITY
FIBERS
HARDNESS
HIGH TEMPERATURE
INTERSTITIAL ATOMS
INTERSTITIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
MICROSCOPY
MOLYBDENUM
MONOCRYSTALS
NIOBIUM
RECOVERY
RECRYSTALLIZATION
REFRACTORIES
SEGREGATION
TANTALUM
THERMODYNAMICS
THICKNESS
TUNGSTEN
WIRES
X RADIATION