································································································································································································································Abstract TiB 2 -reinforced iron matrix composite (Fe-TiB 2 ) powder was in-situ fabricated from titanium hydride (TiH 2 ) and iron boride (FeB) powders by the mechanical activation and a subsequent reaction. Phase formation of the composite powder was identified by X-ray diffraction (XRD). The morphology and phase composition were observed and measured by field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that TiB 2 particles formed in nanoscale were uniformly distributed in Fe matrix. Fe 2 B phase existed due to an incomplete reaction of Ti and FeB. Effect of milling process and synthesis temperature on the formation of composite were discussed.

································································································································································································································Abstract Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent sparkplasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by sparkplasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and fracture toughness of Fe-TiC sintered compact were investigated.

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<p>Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe- TiC composite powders which are fabricated by high-energy ball-milling. A powder mixture of Fe and TiC is prepared in a planetary ball mill at a rotation speed of 500 rpm for 1h. Pressureless sintering is performed at 1100, 1200 and 1300°C for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of 1050°C, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of 50°C, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts show incomplete densification with a relative denstiy of 86.1% after sintering at 1300°C for 3h. Spark-plasma sintering at 1050°C for 10 min exhibits nearly complete densification of 98.6% relative density under the sintering pressure of 50 MPa.</p>