Fabrication of ceramics matrix composite by melt infiltration in situ synthesis and its toughening.

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Liquid aluminum spontaneously infiltrated into the powder mixture of NiO and TiB_2. Then the metallic Ni dispersing alumina matrix composite was in situ fabricated by the such reaction as 3NiO+2Al*Al_2O_3+3Ni, though Al_3Ni was also in situ formed. In this case, 18 vol%TiB_2 particles were required at least for the aluminum infiltration. Moreover, the infiltration behavior of aluminum melt didn't be affected by the addition of large alumina particles of about 1-3mm in diameter into the powder mixture used previously, resulting in revealing sound structure.The resistance to the thermal shock both composite containing such large alumina particles and that free from those particles were better, compared with monolithic alumina.Composite of 58 vol%AIN and 42 vol%Al-Mg alloy could be fabricated by infiltrating the liquid aluminum into the pressed powder preform of Mg_3N_2, and by the reaction such as 2Al+Mg_3N_2*2AIN+3Mg(in Al) at 1473K under nitrogen atmosphere.By infiltrating liquid aluminum into the pressed powder preform composed of BN and Me (Me : Ti or Ta), (MeB_2+AIN) matrix composite dispersing metallic aluminum could be fabricated through the reaction such as 2Al+Me+2BN*MeB_2+2AIN.