Mitsuru Tanino1 and Tokuhiko Nishida1
1Tokyo Research Institute of Yawata Iron and Steel Co., Ltd., Kawasaki
Direct observations were carried out to study the morphology of vanadium carbide V4C3 and the crystallographic orientation relationship between the carbide and matrix in an iron-5% vanadium alloy, containing a small amount of carbon, which was aged at 600°C for various times after quenching from 1200°C into 10% iced brine. The results are as follows: (1) The as-quenched structure consists of simple ferrite and contains a few irregularly distributed dislocations only. Dislocation loops, helical dislocations and precipitates are not present. (2) Large numbers of square or rectangular-shaped thin platelets appear, accompanied by a slight increase in hardness on aging at 600°C. (3) These very thin platelets are identified as vanadium carbide V4C3 containing a small amount of nitrogen by chemical analysis and X-ray diffraction of extracted residues. (4) A definite crystallographic orientation relationship between vanadium carbide and ferrite matrix was determined by analysing a number of electron diffraction patterns as shown in the following:
|(100)V4C3 || (100) α -Fe, V4C3 ||  α -Fe, V4C3 ||  α -Fe.|
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