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The alloy design and efficient routes of TiAl processing are important technological challenges for the development of new aerospace systems. Gamma-TiAl alloys are potential replacements for nickel and conventional titanium alloys in hot sections of turbine engines, as well as in sub-structures of orbital platform vehicles. Powder metallurgy (P/M) of Ti-based alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. This paper aims to investigate the microstructural evolution and densification aspects involved in the obtainment of Ti-48Al-2Cr-2Nb (at.%) alloy by three P/M-processing routes. Samples were prepared from elemental and pre-alloyed powders mixed for 2 h, followed by cold uniaxial and isostatic pressing followed by sintering and hot pressing stages between 1100°C up to 1400°C, for 1 h. After metallographic preparation, sintered samples were characterized by means of scanning electron microscopy (SEM) in the backscattered mode (BSE), X-ray diffraction (XRD), and density measurements. The results showed the potential of TiAl pre-alloyed powders to prevent Kirkendall porosity. A full lamellar microstructure was obtained by the pressureless route while a duplex microstructure was observed in samples produced by the hot pressing route.

Multilayer coatings are synthetic structures constituted by alternate layers of different materials. The technological applications of the multilayer coatings can involve optical, electromagnetism and wear areas. The target of this work is the production of multilayer TiN/ZrN coatings by Electron Beam Physical Vapor Deposition (EB-PVD) over titanium alloys produced by powder metallurgy. P/M-Ti-35Nb-7Zr-5Ta cylindrical samples used as substrates were produced by mixing of the elemental powders with subsequent cold pressing steps and sintering at 1400°C, in high vacuum. TiN/ZrN coatings were obtained by evaporation of alternating Ti and Zr cylindrical targets. The multilayers were characterized by optical and scanning electron microscopy (SEM), chemical analysis via energy dispersive spectrometry (EDS) and Vickers indentation. Besides the possibility of obtaining several layers, the results show coatings with coherent columnar structure, low discontinuity, large and homogenous thickness and high adhesion to substrate.

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