MICROSTRUCTURE AND MECHANICAL PROPERTIES OF TiB2 CERMET

TiB2 based cermet with Fe-Ni-Ti-Al as sintering aids was fabricated by hot-pressing. The effects of sinteringtemperature , holding time and sintering aids on microstructure and mechanical properties were investigated. The toughening mechanism of TiB2 based cermet was analysed. Experimental results show that the bending strength of TiB2 cermetdecreases and the Rockwell hardness increases with sintering temperature rising up ; a bending strength peak appears withholding time prolonged. According to the scanning electron microscope (SEM ) and energy dispersive spectrometer (EDS )observation , Ti in sintering aids is essential for avoiding the formation of extremely brittle secondary borides such as Fe₂Band Ni₂₃B₆ , while Al plays a deoxygen role. Crack deflection and crack bridging are important toughening ways of composite.