Production of Aerospace Tial Intermetallics for High Temperature Applications by Powder Metallurgy

Abstract

During the recent years, alloys based on the intermetallic compound TiAl have attracted a considerable interest as potential competitors to steels and superalloys. Gamma-TiAl alloys are potential replacements for nickel and conventional titanium alloys in hot sections of turbine engines, as well as in orbital platform vehicles. The alloy design and efficient routes of TiAl processing are important technological challenges. Powder metallurgy is a near net shape process that allows the parts production with complex geometry at low costs. In this work, samples of Ti-48Al-2Cr-2Nb (at.%) were prepared from elemental and pre-alloyed powders mixed for 2 h, followed by cold uniaxial and isostatic pressing and sintered between 800 up to 1400°C, for 1 h, under vacuum. After metallographic preparation, sintered samples were characterized by SEM (Scanning Electron Microscopy), density analyses and Vickers microhardness measurements. The results indicated the viability of the pre-alloyed route and the tendency of a full lamellar microstructure of alternating gamma and α2 phases in high sintering temperatures.