Fabrication of TiAl alloys turbocharger turbine wheel for engines by metal injection molding

Abstract

The TiAl turbine wheels possess high acceleration responsiveness and low energy consumption due to its low density, high specific strength and excellent oxidation resistance. However, the mechanical properties of the turbine wheels fabricated by conventional casting can't be fully utilized resulted from inherent defects and compositional segregation. Herein, we used a near-net shaping MIM technology to fabricate this alloy and firstly produced a TiAl alloy turbocharger turbine. The rheological properties of feedstocks, microstructure and mechanical properties were systematically studied. Results indicate that the Feedstock F3 has better rheological properties and no powder-binder separation during injecting using numerical simulation. The microstructure is homogenous and fine-grained fully α2/γ lamellar structure with average size of 111.7 μm. The HIPed TiAl alloy displays excellent mechanical properties which are higher than that of the equivalent casting TiAl alloys. This work presents a valuable method for fabricating complex-shaped TiAl alloy turbine wheels.