Preparation and properties of spherical Ti-35.8Al-18.4Nb alloy powders by VIGA-CC method

Spherical Ti-35.8Al-18.4Nb (mass fraction) alloy powders were prepared by the water-cooled copper crucible vacuum induction melting-gas atomizing (VIGA-CC) technology, using the TiAlNb alloy ingots prepared by vacuum consumable arc melting as the raw material. The properties of the TiAlNb alloy powders were characterized by vibration sieving, scanning electron microscope (SEM), and X-ray diffraction (XRD). In the results, the powder size distribution exhibits a normal state in the range of 45~150 μm. The powder yield with the particle size less than 45 μm is 15.8%, and that larger than 150 μm is 12%. The powder fluidity is 27.2 s·(50 g)^-1. The oxygen increment by mass in the powders is less than 0.01×10^-6, and the total oxygen content by mass in the powders is less than 0.06×10^-6. The TiAlNb alloy powders are mainly composed of γ(TiAl) phase and α₂(Ti₃Al) phase. With the decrease of powder size, the cooling rate increases gradually, leading to the decrease of γ(TiAl) phase and the increase of α₂(Ti₃Al) phase. The powder surface with large size shows the dendritic structure, and that with small size is smooth.