Synthesis of TiAl-Al_2O_3 composites by high energy milling and hot-press sintering

A sub-microstructure titanium aluminide alloy /Al2O3 (3A) composite was obtained by crystallization of the amorphous powders, which were prepared by mechanical alloying (MA) in a planetary ball milling system using Ti-Al-TiO2 as raw materials. The experimental results show that, when the milling time increases up to 30 h, the hcp Ti(Al) supersaturated solid solution disappears, only amorphous phase is left. The compact samples were synthesized by hot-press to 1 200℃with the amorphous as a precursor; the final phases of the matrix and strengthened phase areγ-TiAl and Al2O3. The phases come from in situ crystallization and transformation. The samples, fabricated from the amorphous phase by hot press sintering, have high bending strength and fracture toughness.

A sub-microstructure titanium aluminide alloy/Al2O3 （3A） composite was obtained by crystallization of the amorphous powders, which were prepared by mechanical alloying （MA） in a planetary ball milling system using Ti-AI-TiO2 as raw materials. The experimental results show that, when the milling time increases up to 30 h, the hep Ti（Al） supersaturated solid solution disappears, only amorphous phase is left. The compact samples were synthesized by hot-press to 1 200 ℃ with the amorphous as a precursor; the final phases of the matrix and strengthened phase are y-TiAl and Al2O3. The phases come from in situ crystallization and transformation. The samples, fabricated from the amorphous phase by hot press sintering, have high bending strength and fracture toughness.