TiC-Mo2C-Ni合金の強度におよぼすTiN添加の影響

概要

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The transverse-rupture strength (σm) 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, σm 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 σm, 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 σm, 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.