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For the purpose of improving cutting properties of Ti(C, N) base cermet, the microstructure and several mechanical properties of TiC0.7N0.3-15Ni-8Mo alloy were investigated in relation to the change of additional carbon content. Moreover, in order to clarify the effect of additional carbon content and TiN addition on strengthening of the binder phase, the changes of Ti and Mo concentrations, hardness and lattice parameter of the binder phase of coarse grained TiC-(0, 5, 10, 20) TiN-30Ni-l5Mo alloys were investigated.The results obtained are as follows;(1) The growth of the intermediate phase formed around the core of the hard phase (TiC0.7N0.3) of TiC0.7 N0.3-15M-8Mo alloy in sintering process was not appreciably affected by the change of additional carbon content.(2) The lattice parameter of the binder phase, hardness, transverse-rupture strength, compressive yield strength, and wear resistance in continuous cutting test in turning steel of TiC0.7N0.3-15Ni-8Mo alloy increased with decrease of additional cabon content.(3) Ti concentration in the binder phase of coarse grained TiC-30Ni-15Mo alloy was as much as 4-8% depending on the additional carbon content. On the other hand, Mo concentration was much lower, i.e. 0.5-1.0wt%. Furthermore, Mo concentration in the binder phase of the alloy increased remarkably by the partially replacement of TiC with TiN. In contrast, Ti concentration in the binder phase decreased by 25%-50% with the addition of TiN, the rate of the decrease being smaller with the alloy of lower carbon content.(4) The improvement of the mechanical and cutting properties of TiN bearing low carbon alloy was attributed to the effect of solid solution strengthening of the binder phase through greatly increased dissolution of Mo.

The results obtained are as follows;(1) A1N decomposed in sintering process and the resulting free Al diffused into the binder phase to form γ' phase {Ni3Al(Ti)}.(2) The grain size of the Ti carbonitride particles after sintering did not change by the addition of A1N. The formation of undesirable aluminum oxide particles, which was recognized in the case of the addition of NiAl, was not found in this case. However, large pores were observed in the alloy with 2% A1N.(3) Addition of 1% A1N was found effective for improving both R.T. hardness and R.T. as well as T.R.S. at elevated temperatures.(4) Continuous as well as intermittent cutting tests in turning steel with the 1% A1N added alloy exhibited the most excellent wear and shock resistance.