Fabrication of Micro-fine Spherical TiAl Alloy Powder by High-Energy Ball Milling and Radio Frequency Plasma Spheroidization

Micro-fine spherical TiAl alloy powder was prepared by high-energy ball milling and subsequent radio frequency plasma spheroidization from atomized TiAl alloy powder with big particle size. The fabrication process and powder characteristics were investigated. The results show that the obtained powder exhibits good sphericity. The number-average particle size of the powder can be accurately controlled in the range of 10 similar to 60 mu m, and the powder presents a narrow size distribution with a uniformity level of about 0.63. The powder oxygen content acts as a decreasing function of the particle size, which increases from 2.44 parts per thousand to 3.51 parts per thousand when the number-average particle size decreases from 31.5 mu m to 15.6 mu m. The spherical TiAl alloy power is composed of alpha(2)-Ti3Al and a small amount of gamma-TiAl. The powder possesses homogeneous chemical composition and uniform equiaxed grain microstructure, and the grain size tends to be refined with the decrease of the particle size.