Research On Preparation Of Nanometer TiB₂ TiAl And TiC Powders By Mechanical Alloying

In this paper, we attempted to prepare pure nanometer powders of TiB2, TiAl and TiC respectively by mechanical alloying (MA). The formation mechanism of MA was also discussed on the base study of the impact parameters effect in the MA process.In the system of TiO2-H3BO3-Mg, using the lower-cost TiO2, H3BO3 and Mg powders as raw materials, we studied the effects of ball-milling parameters, as ball to powder ratio (BPR), ball-milling speed and process control agent (PCA), especially the milling time on the mechanical alloying of TiB2 powders. The results showed that the mixed powders of TiB2 and MgO were synthesized by mechanical ball-milling in the shorter ball-milling time with the big BPR;The pure nanometer TiB2 powders were prepared after the acid cleaning, and the average crystallite size of TiB2 reached 82.3nm. As the ball-milling time extends, the average crystallite size of TiB2 steadily decreased. XRD and SEM were used to analyze and observe the powders.Using the extremely common TiO2 as titanium source, the mixed powders of TiB2 and MgO were synthesized by mechanical ball-milling just after being milled for a short time. As a hard phase, MgO can not only prevent the reuniting of TiB2 powder, but also restrain the newly-formed crystal growing effectively;As one by-product, MgO can be eliminated easily in acid cleaning process, and the pure nanometer TiB2 can be obtained.Through the reactive formation, pure nanometer Al3Ti could be fabricated after sintering for 3h at the temperature 900℃. TiAl alloy was attempted to prepare by mechanical alloying with the mixed raw materials of Ti and Al, and TiAl powder was prepared by mechanical ball-milling for 2h. With the ball-milling time extended, the intensity of diffraction peak tended to become weaker and wider. The XRD analysis showed that a part of powders might change to amorphous structure after 36h milling. The possibility of preparing TiC powder by mechanical alloying was discussed, and a preliminary experimental investigation had been conducted. But TiC powder wasn't obtained. Next we try to prepare the TiC through adjusting to the ratio of Ti/C,BPR and etc.