Microstructure and tensile properties of Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd alloy

Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd(atom fraction,%) alloy that forged by 86% was heat treated to be near fully lamellar microstructure(NFL).The microstructures of the deformed alloy and NFL were investigated.Tensile tests at room temperature,700 ℃ and 800 ℃ were carried out.The results show that NFL consists of lamellar microstructure,β phase that locates at lamellar boundaries,and elliptical Gd-compound that disperses in the matrix.The average grain size of the lamellar is 40 μm.The volume fraction of the lamellar,β phase and Gd compound is 93.73%,5.25% and 1.02%,respectively.The tensile tests indicate that the average tensile elongation at room temperature is up to 4.17% and the tensile strength is 865 MPa.At 700 ℃,the average tensile elongation is 22% and the tensile strength is 643 MPa.Compared Ti-44Al-5V-1Cr-0.3Ni-0.1Hf-0.15Gd alloy with TiAl alloys that contain more β phase,the hot deformability is maintained and the room tensile ductility of the studied alloy is much more elevated.It is due to the lower β phase and Gd-compound of the microstructure.