Titanium Aluminide-Based Composite Deposits with Dispersed Nitride Particles Produced by Reactive Thermal Spraying

Abstract

A composite powder is produced by ball-milling of elemental titanium, aluminum and aluminum nitride powders in an argon atmosphere, and is plasma-sprayed in an argon atmosphere, yielding titanium aluminide-based deposits. The constituents of the as-sprayed deposit are Ti₃Al (α2), TiAl (γ) and Ti₂N. Heat treatment of the as-sprayed deposit results in the formation of Ti₂Al(C, N). The carbon in Ti₂Al(C, N) is incorporated into the composite powder during ball-milling due to decomposition of methanol which is used as process controlling agent. There is little difference in hardness between the as-sprayed deposit and the deposits heat-treated at temperatures up to 1473 K. Hardness of the as-sprayed deposit and the heat-treated deposits are higher than that of the cast titanium-aluminum binary alloy whose titanium and aluminum contents are similar to those of the sprayed deposit.