Facile mechanical alloying of titanium sponge

Abstract

The mechanical alloying of titanium with 3wt% chromium was performed starting directly from Hunter or Kroll titanium sponge. A small quantity of calcium was added as a process control agent (PCA) to obtain a high process yield, uniform microstructure and homogeneous chemical composition.The milled powder was then sintered using spark plasma sintering (SPS) at low temperature to achieve the best mechanical properties and a high-quality microstructure. Samples were also heat treated at high temperature to understand the behavior of the chlorine content of the titanium sponge.The mechanical properties were tested by three-point bending. Depending on the kind of starting titanium sponge, high transverse rupture strength (TRS) and high plastic deformation were obtained for all of the alloys in both the as-sintered and heat-treated condition: the high TRS was correlated to the total interstitial elements content.Tensile tests on samples obtained from Hunter titanium sponge yielded results comparable with those of wrought Ti6Al4V, and after high-temperature heat treatment, the samples obtained from the mechanical alloyed powders showed much better properties due to their much smaller grain size compared with that of Ti6Al4V.