Reaction synthesis of ultrafine titanium diborides and nitrides reinforced steel matrix composites in situ by spark plasma sintering

摘要

A novel technique for synthesis of in situ titanium diborides and nitrides reinforced steel matrix composite (TiB2-TiN/Fe) was put forward. In situ TiB2-TiN/Fe composite was synthesised by spark plasma sintering of mechanically mixed ferrotitanium and boron nitride (BN) powders. The phase evolution during sintering indicates that the TiB2-TiN reinforcements are formed in situ as follows: first step, the solid/solid interface reaction between ferrotitanium and BN, resulting in the formation of a small amount of TiB2 and TiN below 1000 degrees C; second step, the solid-liquid solution precipitation reaction in the Fe-Ti-B-N system, resulting in most of TiB2 and TiN reinforcement formation at similar to 1100 degrees C. The microstructure investigation reveals that utrafine TiB2 and TiN reinforcements with a size of similar to 1 mu m are homogeneously distributed in the Fe matrix.