Fabrication of micro-fine spherical high Nb containing TiAl alloy powder based on reaction synthesis and RF plasma spheroidization

• High Nb containing TiAl alloy powders were fabricated with a compact process.
• The process is based on reaction synthesis and RF plasma spheroidization.
• Optimized milling and annealing process can yield alloy powders with fine size.
• Spherical powders obtained possess a mean size of 9.6 μm with narrow distribution.

A compact process for fabricating micro-fine spherical TiAl–Nb alloy powders was developed with a combination of reaction synthesis and plasma spheroidization technique. Powders of TiH2, Al and Nb were firstly mixed and refined by high-energy ball milling, and the mixture was then heated at different temperatures ranging from 600 to 1200 °C for 2 h, allowing synthesis reaction to take place. Ultimately, the synthesized powders melt through radio frequency (RF) argon plasma and rapidly solidified into micro-fine spherical TiAl–Nb alloy powders. The fabrication process and powder characteristics were investigated. With the process described above, the alloy powders with high composition homogeneity and good sphericity can be fabricated. The obtained spherical powders perform a uniform equiaxed-grain microstructure dominated by a supersaturated α2-Ti3Al phase. The powders possess a micro-fine average particle size of 9.6 μm, with a distribution uniformity level of 0.622.

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