Titanium aluminide (Ti-48Al) powder synthesis, size refinement and sintering

- Ti-48Al powder was produced by reaction sintering of elemental powders.
- The fabricated powders exhibited a clear core-rim morphology.
- A variety of grinding methods were assessed to reduce the Ti-48Al particle size.
- Shatterbox milling was seen to be the most efficient method to reduce particle size.
- Reducing the particle size resulted in significantly improved sintering response.

Titanium aluminide based alloys have shown significant potential in high temperature applications, but the high production cost of TiAl considerably limits its utilisation. Although the use of powder metallurgy processes can reduce the cost by minimising post-machining, an economical powder production route is still required. Therefore, in the present study a pre-alloyed Ti-48Al powder is developed using an elemental Ti and Al powder blend prepared using a simple vacuum heat treatment. A formation model of the intermetallic phases (i.e. TiAl, Ti3Al, TiAl2, TiAl3) during powder synthesis is proposed. In order to improve the sinterability, various milling methods (i.e. ball, attrition and shatterbox milling) are examined to reduce the particle size. The sintered microstructures, particularly the two-phased (α2-Ti3Al γ-TiAl) lamellar structures are also investigated. Improved densification is achieved at 1300 °C, held for 2 h, using the manufactured powder, compared to the elemental powder blend (∼55%). With higher sintering temperatures or longer hold periods, increased density TiAl components are possible.

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