Evaluation of the possibility of obtaining spherical powders of titanium alloy Ti 6Al 4V by supersonic reverse polarity plasma torch for use in additive manufacturing

This work demonstrates the possibility of producing spherical Ti-6Al-4V Grade 5 alloy powders with superior technological properties compared to those obtained through conventional industrial gas atomization methods for additive manufacturing, by utilizing plasma atomization of a 1.0 mm diameter solid wire.The process employs supersonic plasma jets generated by a DC reverse polarity plasma torch with vortex arc stabilization.The plasma torch has a copper hollow electrode-anode and a special diffusive nozzle-cathode.Analysis of the particle size distribution of the powder showed the main fraction of -140 m 96 wt%, and the amount of the finely-divided fraction of -63 m is up to 55-60 wt%.Also, using subsonic jet had been give fraction -250 m, which is 97 wt%, and the amount of the finely-divided fraction -63 m does not exceed 30 wt%.The study of the shape and structure properties of Ti-6Al-4V Grade 5 powder showed that the sphericity coefficient reaches up to 0.9, the number of defects in the form of satellites and irregular particles does not exceed 1 wt%.In terms of technological characteristics, Ti-6Al-4V Grade 5 powder obtained by the adopted technique is on par with the industrial method of producing spherical powders for additive manufactuing by the direct polarity plasma torches.