Ni-Mo-C合金中に析出するMo₂Cの透過電子顕微鏡観察

抄録

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 {00·1}_Mo2C and six side planes of {10·0}_Mo2C type. The plate forms on {111}_Ni matrix planes. Its orientation relationship with the matrix is (00·1)_Mo2C\varparallel(111)_Ni, [11·0]_Mo2C\varparallel[1\bar10]_Ni.
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.