Microstructural investigation of Ti-48Al-2Cr-2Nb (at.%) obtained by powder metallurgy using hot uniaxial pressing

The aim of this paper is to analyze the microstructural development in samples of Ti-48Al-2Cr-2Nb (at.%) alloys obtained by powder metallurgy (P/M). This alloy has potential applications when high operating temperatures are required, e. g. turbines, aerospace applications, automotive engines valves and turbocharger rotors. The elementary powders were mixed for 1 hour, cold uniaxially pressed at 60 MPa and sintered at 1100°C, for 1 hour, under vacuum. Then, the specimens were milled and submitted to a second stage that included cold isostatic pressing (400 MPa) with subsequent hot uniaxial pressing (20 MPa), between 900 up to 1200°C, for 2 hours, in argon atmosphere. The alloys were characterized by XRD (X-ray diffraction), SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy) and Vickers microhardness measurements. The results indicated the viability of the route and the tendency of a lamellar microstructure in high sintering temperatures.