Makoto Kikuchi1, Tohru Tanaka2 and Ryohei Tanaka1
1Department of Metallurgy, Faculty of Engineering, Tokyo Institute of Technology, Tokyo
Morphology of Mo2C precipitated in a Ni-9.0 at%Mo-0.83 at%C alloy aged at 900°C has been studied by means of transmission electron microscopy. The shape of intragranularly precipitated Mo2C is a thin hexagonal plate having two broad faces of 00 ⋅ 1Mo_2C and six side planes of 10 ⋅ 0Mo_2C type. The plate forms on 111Ni matrix planes. Its orientation relationship with the matrix is (00⋅1)Mo_2C//(111)Ni, [11⋅0]Mo_2C//[1
The growth direction as well as the orientation relationship of Mo2C fibres observed in isothermally transformed Fe-Mo-C alloys by other investigators has been discussed on the basis of the present observations.
The stacking fault energy of Mo2C is estimated to be relatively small. This accounts for the frequently observed stacking fault in the Mo2C plate precipitated in the present alloy.
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