SYNTHESIS AND CHARACTERIZATION OF METALLIC-INTERMETALLIC Ti-TiAl3, Nb-Ti-TiAl3 COMPOSITES PRODUCED WITH ELECTRIC-CURRENT-ACTIVATED SINTERING (ECAS)

摘要

In this study, we investigated the fabrication of in-situ metallic-intermetallic Ti-TiAl3 and Nb-Ti-TiAl3 composites from a powder mixture containing w = 40 % titanium and w = 60 % aluminum with (w = 5 % and w = 10 %) and without a metallicniobium addition. Powder mixtures without a binder were compressed uniaxially under a pressure of 130 MPa and sintered at a current of 2000 A for 20 min in a steel mould using the electric-current-activated sintering method. The microstructures of the sintered samples were investigated with light and scanning electron microscopes, the phases in the samples were analyzed with XRD and their hardness was measured with a Vickers hardness tester. Light and scanning electron microscope (EDS) investigations showed that the microstructures of non-reinforced titanium-aluminum samples consisted of two components: the main component was titanium aluminide and the other one was metallic titanium. Also, there was a trace amount of aluminum oxide in the sintered body. XRD analyses also demonstrated that the main phase in the composite is TiAl3. The XRD analyses of the samples reinforced with w = 5 % and w = 10 % of niobium to enhance the ductility of the body showed that metallic niobium and Ti-TiAl3 remained the main phase. In addition, the average hardness values of the samples of the non-reinforced Ti-TiAl3 composite, w = 5 % Nb-reinforced Ti-TiAl3 composite and w = 10 % Nb-reinforced Ti-TiAl3 composite were measured to be about (759, 669 and 600) HV, respectively.