Ti6Al4V nanocrystalline and nanometric powder manufacturing and characterization for Additive Manufacturing

The use of nanostructured materials as a build material for Additive Manufacturing (AM) can potentially lead to increased productivity, due to the hypothesis that nanostructured raw materials can be layer-sintered with lower specific energy, and consequently lower processing times when compared to commercial powders. Nanostructured, also termed nanocrystalline, powders have particle dimensions in the micro-scale (mean size is generally around 30 µm), but grain size in the order of 10^-8 ÷ 10^-9 m. Sintering of such materials can be very rapid as compared to conventional powders. In addition, using nanostructured or even nanometric (nano-sized particles) powders can result in higher density and hardness values of the sintered part, using the same process parameters. Nanocrystalline and nanometric metal powders can represent a strong innovation in AM. This work presents our results concerning the manufacturing and characterization of Ti6Al4V powders, with potential use in AM. The powders were manufactured using two procedures: i) mechanical milling from commercially available titanium alloy rods, with various rotation speeds and milling periods, in order to obtain nanometric particles; ii) rapid cooling from Ti6Al4V melts, in order to obtain nanocrystalline structures, further mechanically milled.