Interdiffusion Behavior of Aluminide Coated Two-Phase α2-Ti3Al/γ-TiAl Alloys at High Temperatures

Lower density materials of TiAl based intermetallic alloys have recently attracted intensive attention for the replacement of nickel-based superalloys used at high temperatures. As aluminium-rich titanium aluminide intermetallic compounds are normally brittle, two-phase α2-Ti3Al/γ-TiAl alloys have been developed. To increase the corrosion resistance of these alloy systems, an aluminide coating of TiAl3 layer is normally applied. During operation at high temperatures, however, interdiffusion between the coating and the alloy substrate can occur and decrease the TiAl3 layer thickness of the coating. The effects of temperature exposure on the growth of the TiAl2 interdiffusion zone layer on two-phase α2-Ti3Al/γ-TiAl alloys with a chemical composition of Ti-47Al-2Nb-2Cr-0.5Y-0.5Zr are presented in this paper. The exponents for kinetics and rate constant of the TiAl2 interdiffusion layer growth of this multi-component system were found under variation of temperature. The results were compared with those from other researchers

The Effect Of Aluminum Content On Properties Of TiAI Based Binary Alloys.

Four alloys in Ti-AI binary system (Ti-50AI, Ti-53AI, Ti-60AI and Ti-65AI in at.%) have been produced by orc-Inclting process in a specially-designed and locally made furnace . The alloy samples were then oxidized in air a! 900°C 50 hours inside a muffle furnace. In this study microstructures and phases of the alloys have been characterized using XRD and SEM/EDS to link on their properties

Cyclic Oxidation of Aluminide Coated Two Phase α2-Ti3Al/γ-TiAl Alloys at 1000oC

AbstractTitanium aluminide alloys have been considered as the candidates to substitute nickle-base superalloys for high temperature applications in aircraft turbine engines, as the alloys has lower density. For such applications, the alloys should exhibits both strength and high temperature oxidation or corrosion. Therefore, external protective scale of Al2O3 has to be easily developed in the alloys, and the scale should resist for cyclic thermal operations. Recently, pack aluminide coatings have been developed on two phase α2-Ti3Al/γ-TiAl alloys of Ti-47Al-2Nb-2Cr-0.5Y-0.5Zr, to provide TiAl3 based coatings capable in providing external scale of Al2O3. Nevertheless, no cyclic oxidation test has been conducted in this system. This paper reports the cyclic oxidation behavior of un-coated and pack aluminide coated α2-Ti3Al/γ-TiAl alloys at 1000oC