The Two-Phase Region in TiC-Mo-30%Ni Alloys

The phenomena relating to the two-phase region in TiC-Mo-30%Ni alloys have been studied in order to obtain basic information as to the properties of TiC-Mo-Ni alloy systems.TiC-(0∼30)%Mo-30%Ni alloys were vacuum-sintered at 1300°∼1450°C. The average cooling rate from sintering temperatures to 700°C was about 24°C/min.The results obtained were as follows: (1) The width and location of two-phase region in each alloy seemed not to be affected by the sintering temperatures. (2) The two-phase region of the straight alloy was in the range of 18.1 to 19.3%C(calculated in terms of the carbon content in cabide). The two-phase region in the straight alloy was extended with increasing addition of Mo. For example, the phase region of the 30%Mo alloy existed in the range of 12.7∼14.5%C. (3) The added Mo appeared to dissolve in titanium carbide in the form of Mo2C. (4) Compositions of the binder and carbide phases of each alloy showed a definite variation in the two-phase region with carbon content, as has been confirmed in various WC-Co base alloys. The dissolved amount of Ti in the binder phase of the straight alloy was found to change sharply in the two-phase region from a minimum of about 3% (in the highest carbon alloy) to a maximum of about 10% (in the lowest carbon alloy). Even in the alloys containing Mo, the dissolved amount of Ti was nearly the same as in the straight alloy, but in this case Mo also dissolved in the range from about 0 to 6% depending on the Mo and the carbon contents. (5) The dissolved amount of Ni in titanium carbide was about 0.4% in the straight alloy. The amount of Mo dissolved in the ε phase was about 5% in the alloys containing Mo. (6) The corrosion and oxidation resistance of the alloys were confirmed to vary as can be expected from the change in composition of the binder phase.