Effective two-step method for producing Ti–6Al–4V alloy particles with various morphologies

Magnesium was used as a reductant for the direct combustion synthesis of titanium alloy particles (Ti–6Al–4V) from titanium oxide (TiO2). The feed material (TiO2) and reductant (Mg) were mixed with Al (or AlCl3 · 6H2O), vanadium pentoxide (V2O5), and calcium hydroxide (Ca(OH)2), and the reaction mixture was combusted under pressurized argon. Temperature–time profiles were intermittently measured during combustion to analyze the combustion temperatures and wave velocities. The combustion product was subsequently acid-leached to eliminate secondary phases (MgO, MgCl2, CaO) and produce Ti–6Al–4V alloy particles whose oxygen content was ~ 1.3%. Further the content of oxygen was decreased to 0.2 wt.% by deoxidizing the Ti–6Al–4V alloy particles with calcium in the range 850–900 °C. The AlCl3 · 6H2O affected the particle morphology more than the Al metal did; i.e. the Al-doped alloy particles were porous and consisted of relatively small agglomerated particles whereas using AlCl3 · 6H2O produced dense, round particles. Pilot-scale production experiments revealed that Ti–6Al–4V alloy particles can be efficiently produced using our method.