Microstructure evolution and mechanical properties of Ti-46.5Al-4Nb-1Cr-0.2Ta alloy during near-isothermal forging at α single-phase region

Abstract

For TiAl alloys, forging in the α single-phase region is an important and efficient method to obtain fine lamellar structure. In this study, Ti-46.5Al-4Nb-1.8Cr-0.2Ta (at.%) alloy was fabricated using direct single-pass forging near α transition temperature (α-DSPF), the microstructure evolution and mechanical properties were investigated. The results show that the refined near lamellar structures were obtained by means of recrystallization of α phase through near-isothermal forging at 1390 °C. Finally, the yield strength, ultimate tensile strength and elongation of the as-forged alloy at 1390 °C were simultaneously improved due to the improvement of lamellar fraction, refinement of grain size and reduction of the β_o phase. This work provides a promising and cost-effective method for α-processing of TiAl alloys to improve the mechanical properties.