A TITANIUM CARBOSULPHIDE PHASE IN ALLOY STEELS AND SUPERALLOYS

The morphology, optical characteristics and composition of a titanium carbo-sulphide phase ccurred in certain low-alloy steels, stainless steels and superalloyshave been investigated by optical icroscopy, TEM and EPMA. Its crystallinestructure has been identified by selected-area electron diffraction echnique. Depend-ing on the mechanism of formation, this phase exhibits two different growthhabits: latelets formed directly from the molten alloy are distributed at cast grainboundries, while very thin aminae were precipitated at austenitic grain bound-aries during cooling from a high temperature. It appears hat the amount of thisbrittle phase in the alloys can be greatly diminished by the addition of smallamounts f rare-earth elements. The composition of this phase is found as:(Ti_(1-m)X_m)_2S(C_(1-n)N_n)