Characterization of TiAl Powders Prepared by Plasma Rotating Electrode Processing

Ti-47Al-2Cr-2Nb Spherical powders were fabricated directly from the master electrode by the plasma rotating electrode processing (PREP) and the products were analyzed by XRD, SEM, EPMA etc. The average particle size d(50) of the powder is 85 mu m, the loose density is 2.65 g/cm(3), the flowability is 10.40 s/50 g, and the sphericity is 99.6% tested via a line transversal method. The mean content of oxygen and nitrogen is 0.05% and 0.004%, respectively. XRD patterns indicate that the obtained powders consist of Ti-rich alpha(2)-Ti(3)Al and a few gamma-TiAl phases, while for the as-HIPed sample the main phase is gamma phase with a few alpha(2) phase. SEM images with back scattered mode analysis show that the grains of the powder particles are of cellular structure with average size of about 2 mu m. EMPA test for a series of different diameters powders indicates that the chemical composition in center is closed to that of prealloyed rod, except the surface of the powder where the evaporation of Al is about 2at%.