Homogenization and hot working of Ti-48Al-2Nb-2Cr alloys

γ-TiAl based alloys are rapidly being developed for elevated temperature applications, due to their high strength, light weight and oxidation resistance. The majority of this work has focused on alloy modifications through compositional controls, alloying additions and thermomechanical processing to improve the low temperature ductility and toughness and high temperature creep resistance. Ingot metallurgy (I/M) processing, such as isothermal forging of cast products, has been the primary method of materials fabrication. However, frequently the cast forging stock has not been homogenized to eliminate casting segregation inherent in these alloys. The segregation is particularly pronounced when refractory elements, such as Nb, Ta and W, are added to the alloy. Unfortunately, the segregation persists after hot working and can not be eliminated by low temperature heat treatments after deformation. Instead, the segregation must be eliminated prior to hot working. Therefore, the homogenization and hot workability after homogenization of Ti-48AI-2Nb-2Cr alloys was examined. Samples were heat treated in the α + γ phase field and the α phase field in order to determine the homogenization behavior of the materials. Recrystallization of the materials homogenized in the α-phase field was examined after heat treatment in the α + γ field (static), after limited hot deformation (dynamic), and after limited hot working and heat treatment in the α + γ phase field. Finally, the hot workability of selected samples was evaluated and compared to powder metallurgy (P/M) materials