TiC-Mo₂C-Ni合金の強度におよぼすTiN添加の影響

抄録

The transverse-rupture strength (σ_m) and the strength (σ₀) of the sound matrix free from structural defects of TiC-(0, 20)%Mo₂C-(0-30)%TiN-20%Ni alloys were investigated at room temperature as a function of the amount of additional titanium nitride (TiN).
The results obtained were as follows: (1) The effects of TiN addition on the carbide grain size, σ_m and σ₀, were found to be negligible in TiC-20%Ni alloy, while remarkable in TiC-20%Mo₂C-20%Ni alloy. (2) In TiC-Mo₂C-TiN-Ni alloys, additional TiN generally formed carbonitride with TiC and Mo₂C around TiC particles, and decreased the grain size of carbonitride including TiC core with increasing TiN contents up to about 15%TiN. The σ₀ value increased with increasing TiN contents and attained to a maximum at this TiN content. The σ_m, value, however, decreased with increasing TiN contents, owing to the increased dimension of defects which acted as a fracture source. From the results, it was estimated that σ_m, for example, of TiC-20%Mo₂C-15%TiN-20%Ni alloy would exceed about 290 kg/mm² (according to JIS) when the dimension of defects is decreased to values of about 5μ in average. Brief consideration was also given as to the results mentioned above.