Formation of niobium carbides in high-dose carbon-ion-implanted and annealed niobium

Conference · Mon Oct 30 04:00:00 EST 1989

DOI:https://doi.org/10.1557/PROC-157-795· OSTI ID:5449117

Huang, J. S.

Polycrystalline niobium was implanted with 200-keV C{sup +} ions to a total fluence of 7 {times} 10{sup 17} carbon ions per cm{sup 2}(C/cm{sup 2}). Auger electron spectroscopy (AES) analysis showed that the carbon concentration varied from 5 to 50 at. % within a depth of about 4000 {Angstrom}. Glancing-angle x-ray diffraction analysis (XRDA) and transmission electron microscopy (TEM) analysis indicated that no Nb{sub 2}C phase was formed and that a buried fcc NbC layer was formed in the region where carbon content exceeds about 40 at. %. The absence of Nb{sub 2}C was attributed to the low diffusivity of carbon atoms and the fact that it could form only as an intermetallic compound. As a result of the TEM analysis and the fact that the diffusivity of carbon is very small, the formation of NbC is described as a type of diffusionless martensitic transformation. When the implanted samples were annealed at 1273 K for 1 h, the implanted carbon redistributed, the NbC phase disappeared, and an orthorhombic Nb{sub 2}C phase formed as spherical precipitates. 14 refs., 3 figs., 1 tab.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5449117
• Report Number(s): UCRL-102036; CONF-891119--28; ON: DE90003601
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360106* -- Metals & Alloys-- Radiation Effects
ANNEALING
AUGER ELECTRON SPECTROSCOPY
CARBIDES
CARBON COMPOUNDS
CARBON IONS
CHARGED PARTICLES
CRYSTAL STRUCTURE
ELECTRON SPECTROSCOPY
ELEMENTS
HEAT TREATMENTS
ION IMPLANTATION
IONS
METALS
NIOBIUM
NIOBIUM CARBIDES
NIOBIUM COMPOUNDS
PHASE STUDIES
REFRACTORY METAL COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS