| TiAl-based alloys as a new generation high-temperature structural appliactions inaerospace industries, due to their attractive propeities, such as high specific strength andspecific modulus, high resistance to oxidation, excellent creep properties, has attractedmuch more attention. However, low room temperature ductility and poor formability limittheir extensive applications. Therfore, the hot deformation behaviors and microstuctureevolution should be studied. Hot compression deformation of as-cast and as-extrutionTi-44Al-5V-1Cr alloy were investigated with a Thermecmastor-Z thermal simulationcompression tests in this present study. Additionally, the microstucture evolution featuresas well as the soft deformation mechanism of current alloy were studied systematically.The hot deformation results indicate that the flow stress of the as-cast andas-extrusion materials of Ti-44Al-5V-1Cr alloy were both increases with increasing strainrate and decreasing defomation temperature. The results show that the alloy of both stateexhibits negative temperature sensitivity and positive strain rate sensitivity. Therelationship between peak stress and deformation conditions for the alloy of both state canbe described by a hyperbolic-sine type equation which used to study thermal activationenergy and their constitutive equations.Combined the as-cast Ti-44Al-5V-1Cr alloy microstucture evolution with hotprocessing window, the soft mechanism at different regions were discussed. An optimizedhot processing conditions for as-cast Ti–44Al–5V–1Cr alloy were obtained.The hot processing map of as-extrution Ti–44Al–5V–1Cr alloy was developed at astrain of0.3on the basis of dynamic material modeling and Prasad criteria. The softdeformation mechanism of as-extrution Ti–44Al–5V–1Cr alloy were studiedsystematically and a new superplasticity phenomenon were discovered. An optimizedsecondary hot processing windows for as-extrution Ti–44Al–5V–1Cr alloy were obtained. |
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