Synthesis and Characterization of the in-situ Ti3SiC2 / Al2O3 Composite by SPS of Mechanically Activated Powders of TiO2, Al, C, and Si

The formation of Ti3SiC2-Al2O3 composite by mechanical alloying and thermal treatment of TiO2, Si, Al, and graphite powders was investigated. The ball milling process was carried out for up to 40 h. To evaluate the formation mechanism of Ti3SiC2-Al2O3, both as-mixed and 40 h milled powder samples were annealed for 1 h at 1400 degrees C and 40 h milled sample was thermally treated by differential thermal analysis. Al3Ti and Al2O3 were only formed after 40 h of milling. The Ti3SiC2 MAX phase was formed after annealing 40 h milled powder at 1400 degrees C for 1 h. The results illustrated that the mechanism of Ti3SiC2 formation consisted of Al3Ti/Al2O3, TiC, and TiSi2 formation, the reaction among TiC and TiSi2 as well as Ti3SiC2 formation. The annealed 40 h milled powder was sintered by a spark plasma sintering process. The sintered sample was dense without any phase change and the nanoindentation result indicated a hardness of 9.52GPa with an elastic modulus of 316 GPa.