University of Cambridge

Vanadium Carbide in Tempered Martensite

S. Yamasaki and H.K.D.H. Bhadeshia



Crystal Structure of Vanadium Carbide

Vanadium carbide (VC) has a cubic-F lattice with a motif of a vanadium atom at 0,0,0 and a carbon atom at 0,0,0.5. However, although illustrated here as a stoichiometric carbide, the carbon concentration tends to be less than 50%. There are also ordering reactions that occur in the carbide which are not illustrated here. The lattice parameter is assumed to be 0.4159 nm. The blue atoms represent vanadium and carbon is designated black.

101
Vanadium carbide: projection of crystal structure along 101 direction
111
Vanadium carbide: projection of crystal structure along a 111 direction
cube
Vanadium carbide: projection of crystal structure along a cube edge


Transmission Electron Microscopy

The following micrographs are taken from thin-foil samples studied using a transmission electron microscope.

0175-01V-2-291
Tempered martensite in Fe-V-C steel.
0179-01V-2-295
Tempered martensite in Fe-V-C steel.
0183-01V-2-299
Tempered martensite in Fe-V-C steel.
0376-01V-3-220
Tempered martensite in Fe-V-C steel.
0382-01V-3-226
Tempered martensite in Fe-V-C steel.
0384-01V-3-228n
Tempered martensite in Fe-V-C steel.
0686-01V-4-337
Tempered martensite in Fe-V-C steel.
0687-01V-4-338
Tempered martensite in Fe-V-C steel.
0693-01V-4-344
Tempered martensite in Fe-V-C steel.
0868-01V-5-426
Tempered martensite in Fe-V-C steel.
0869-01V-5-427
Tempered martensite in Fe-V-C steel.
0872-01V-5-430
Tempered martensite in Fe-V-C steel.
1079-01V-6-420
Tempered martensite in Fe-V-C steel.
1081-01V-6-422
Tempered martensite in Fe-V-C steel.
1082-01V-6-423
Tempered martensite in Fe-V-C steel.
1195-01V-3-492
Tempered martensite in Fe-V-C steel.
1198-01V-3-495
Tempered martensite in Fe-V-C steel.
1200-01V-3-497
Tempered martensite in Fe-V-C steel.

Titanium-vanadium carbide in steel


A. R. Waugh

An imaging atom-probe study of a mixed carbide particle in a steel containing titanium and vanadium. Bob wanted to confirm that there is a disturbance in the trajectories of the carbon at the edges of the particle, since the carbon distribution goes beyond the boundaries of the carbide particle. The possibility of such an aberration had been suggested to him by P. Turner.



Photographs courtesy of Dr Sally Waugh.

Titanium/vanadium carbide in steel, imaged while the specimen is at 60 K.
titanium carbide, vanadium carbide, mixed carbide, steel, A. R. Waugh

Neon field-ion image.
.

titanium carbide, vanadium carbide, mixed carbide, steel, A. R. Waugh

An image with just the Fe2+ ions, showing the absence of iron in
the carbide particle.

titanium carbide, vanadium carbide, mixed carbide, steel, A. R. Waugh

An image using the carbon C2+ ions.

titanium carbide, vanadium carbide, mixed carbide, steel, A. R. Waugh

Combined image of the C2+ ions superimposed on the field-ion image.



titanium carbide, vanadium carbide, mixed carbide, steel, A. R. Waugh

Schematic of imaging atom probe apparatus.











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