Microstructure and mechanical properties of gamma titanium aluminide alloys fabricated by metal injection molding using non-spherical powder

Metal injection molding (MIM) is a very effective way to prepare brittle TiAl alloy parts. In this study, the rheological properties of feedstocks, as-sintered microstructure, interstitial impurities, and mechanical properties by using inexpensive non-spherical powders were systematically studied. By optimization of raw materials and strict process control, semi-alloyed Ti-48Al powder was prepared by self-propagation synthesis. The powder is composed of TiAl, Ti3Al, and TiAl3 with an O content of 0.34 wt%. The pseudo-plastic flow behavior and powder loading of feedstock based on different binder systems-polyoxymethylene (POM) and paraffin wax (PW)-were systematically studied. Sintering of non-spherical TiAl powder at 1450 degrees C yielded samples with a relative density of 96.4%, a tensile strength of 352 MPa, and elongation of 0.32%, reaching the level of as-cast alloys. In addition, microstructures of samples sintered at various sintering temperatures were also studied in detail and compared with the structure of the ingot metallurgy TiAl alloy.