Structure of dislocations in tantalum and tantalum-nitrogen alloys

Journal Article · Mon Dec 01 04:00:00 EST 1975 · Acta Metall., v. 23, no. 12, pp. 1461-1468

DOI:https://doi.org/10.1016/0001-6160(75)90155-8· OSTI ID:4087358

Welsch, G; Gibala, R; Mitchell, T E

Weak-beam electron microscopy of Ta and Ta--N crystals deformed at 77$sup 0$K shows that the image widths of $sup 1$$/$$sub 2$[111] screw dislocations are approximately 10 to 25 A, regardless of the nitrogen concentration between approximately 5 and 15,000 at. ppM. Annealing treatments designed to decorate screw dislocations with nitrogen atmospheres have no effect on the widths. Furthermore, no dissociations are observed at the nodes of the dislocation reactions $sup 1$$/$$sub 2$[111] + $sup 1$$/$$sub 2$[1 anti 11] = [100]. It is concluded that the splitting of screw dislocation cores of approximately 50 A observed by field ion microscopy is enhanced by the local electric field; actual dissociations must be much smaller. Models of interstitial hardening in bcc metals which rely on interstitial-enhanced core expansion of screw dislocations are also not supported by the present results. (auth)

• Research Organization: Case Western Reserve Univ., Cleveland
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-020793
• OSTI ID: 4087358
• Journal Information: Acta Metall., v. 23, no. 12, pp. 1461-1468, Journal Name: Acta Metall., v. 23, no. 12, pp. 1461-1468; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

*TANTALUM NITRIDES-- CRYSTAL STRUCTURE
*TANTALUM-- CRYSTAL STRUCTURE
360102* --Materials--Metals & Alloys--Structure & Phase Studies
ANNEALING
BCC LATTICES
DEFORMATION
DISLOCATIONS
ELECTRIC FIELDS
ELECTRON MICROSCOPY
HARDENING
INTERSTITIALS
ION MICROSCOPY
MEDIUM TEMPERATURE
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
SCREW DISLOCATIONS