Publication: Microstructural design in with high cooling rates
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2015-06
Defense date
2015-07-10
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Abstract
Gamma titanium aluminides are intermetallic alloys with great potential for aerospace applications in advanced aerospace engine and high-temperature airframe components and, in particular, in low pressure turbines (LPT), because they can provide increased thrust-to-weight ratios and improved efficiency under aggressive environments at temperatures up to 750 °C. Thus, - alloys are projected to replace the heavier -base superalloys currently used for LPT blades manufacturing. These alloys offer low density, high specific strength, creep and corrosion resistance at high temperatures. Figure 1 compares their mechanical behavior with that of other high temperature alloys at a wide range of temperatures. However, the wide commercialization of gamma titanium aluminides is prevented by their low ductility as well as by the lack of quantitative models relating the microstructure and the mechanical behavior. Moreover, their full potential has not been exploited because a thorough knowledge on the possibilities for microstructural development upon cooling from the liquid phase or from high temperature phase domains is still lacking. The aim of this project is to contribute to fill this knowledge gap by taking advantage of Gleeble technology and, in particular, of the possibility to use extremely high and well measured cooling rates to generate novel microstructures in a Ti-45Al-2Nb-Mn(at.%)+0.8(vol.%)TiB2 (Ti4522XD) alloy. The developed microstructures are thoroughly characterized by optical, scanning and transmission electron microscopy and a link with their mechanical behavior, evaluated by hardness measurements, is established.
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Intermetallic alloys, Gamma titanium aluminides, Microstructural design