Mo_2CとSiとの, その場固相交換反応による(MoSi_2, Mo_5Si_3)/SiC複合体の合成

概要

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The intermetallic compound, MoSi_2, has great potential as an elevated-temperature structural material but it exhibits some undesirable properties such as low fracture toughness and low strength at elevated temperatures. Improvement of these properties can be achieved by reinforcing MoSi_2 with the addition of SiC particles or whiskers, or by alloying it with Mo_5Si_3. The preparation of MoSi_2 composites from powders gives rise to an oxidation problem since SiO_2 covers the raw powder. To avoid this problem, the material must be prepared in situ. In this work, multiphase composites based on the Mo-Si-C system have been prepared using a solid-state displacement reaction between Mo_2C and Si. Samples were prepared from a mixture, containing different proportions of Si and Mo_2C powders, which was pelletized under vacuum at 40 MPa and heat-treated in argon. The pieces obtained exhibit different proportions of SiC, MoSi_2 and Mo_5Si_3. The microhardness obtained ranges from 12 to 14 GPa, and K_c is over 8 MPa・m^<1/2> which is higher than that of pieces made of MoSi_2 only.
社団法人日本セラミックス協会の論文
2000-11-01