In Situ Formation of Ti-TiAl₃ Metallic-Intermetallic Composite by Electric Current Activated Sintering Method

In this study we have investigated fabrication of in situ metallicintermetallic Ti-TiAl3 composites from powder mixture containing 40 wt % Ti-Al, 50 wt % Ti-Al and 60 wt % Ti-Al by electric current activated sintering method. Powder mixtures without additive were compressed uniaxially under 130 MPa of pressure and sintered 2000 A current for 20 minutes in a steel mould. Microstructures of sintered samples were investigated by optic and scanning electron microscopes, phases in samples were analyzed by XRD and their hardness was measured by Vickers hardness tester. Optic and scanning electron microscopes investigations showed that microstructures of samples were consisting of two components: Main component was titanium aluminide and other was metallic titanium. Besides this there was a trace amount of aluminium oxide in the sintered body. XRD analyses also demonstrated that main phase is TiAl3. It was determined that as weight percentage of titanium in the mixture was decreasing, also the amount of metallic titanium has decreased in the sintered body. Additionally, average hardness values of samples were about 500 HV