Microstructural evolution and creep deformation behavior of novel Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(at.%) orthorhombic alloy

The microstructural evolution and creep deformation behavior which were adjusted and controlled by age treatment of a novel Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(mole fraction,%)alloy,were investigated.The microstructures were obtained at different heat treatment temperatures and analyzed by SEM and TEM techniques.The creep behavior of the alloy was studied at 650℃,150 MPa for 100 h in air.The results showed that the initial microstructure mainly contained lath-likeα2,B2,and O phases.The precipitated O phase was sensitive to aging temperature.With the aging temperature increasing,the thickness of the precipitated O phase was also increased,and the length was shortened.The creep resistance of this alloy was relevant to the morphology and volume faction of the lamellar O phase.The increase of lamellar O phase in thickness was the main reason for the improved creep properties.

Recrystallization behavior of Ti40 burn-resistant titanium alloy during hot working process

The recrystallization behavior of deformed Ti40 alloy during a heat-treatment process was studied using electron backscatter dif- fraction and optical microscopy. The results show that the microstructural evolution of Ti40 alloy is controlled by the growth behavior of grain-boundary small grains during the heating process. These small grains at the grain boundaries mostly originate during the forging proc- ess because of the alloy＇s inhomogeneous deformation. During forging, the deformation first occurs in the grain-boundary region. New small recrystallized grains are separated from the parent grains when the orientation between deformation zones and parent grains exceeds a certain threshold. During the heating process, the growth of these small recrystallized grains results in a uniform grain size and a decrease in the av- erage grain size. The special recrystallization behavior of Ti40 alloy is mainly a consequence of the alloy＇s high β-stabilized elemeutal con- tent and high solution strength of the β-grains, which partially explains the poor hot working ability of Ti-V-Cr-type bum-resistant titanium alloys. Notably, this study on Ti40 bum-resistant titanium alloy yields important information related to the optimization of the microstruc- tures and mechanical properties.

Microstructure and mechanical properties of a new Ti2AlNbbased alloy after aging treatment

A new TiAlNb-based alloy with the composition of Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si(at%) was fabricated in the sequence of arc melting, forging, solid solution and aging. Present paper focuses on the effects of aging temperatures(700, 750, 800, 850 and 900 ℃) on microstructure, room-temperature tensile properties as well as tensile properties at 650 ℃ and creep properties at650 ℃/150 MPa. It is obvious that the aging treatment promotes the precipitation of O lathes from B2 matrix.With aging temperature increasing, the content of O phase decreases and its size increases gradually, which leads to the decrease in tensile strengths both at room temperature and 650 ℃ and a little increase in ductility. For creep properties, the sample aged at 700 ℃ shows the best creep resistance due to its extremely high O phase content. Aging at 800 ℃ leads to the decrease in the content of O phase and softening of the alloy significantly. However, with aging temperature further increasing from 800 to 900 ℃,the precipitated O phase will be coarsened gradually, which strengthens the alloy again.

Physical properties of WSTi3515S burn-resistant titanium alloy

Development of burn-resistant titanium alloys is the most direct way of mitigating the ignition and propagation of titanium fires in jet engines. WSTi3515S alloy（Ti–35V–15Cr–0.3Si–0.1C） is a new high alloying beta type burn-resistant titanium alloy, belonging to Ti–V–Cr type alloys which have been made significant progress in engineering technology in the past 5 years. The physical properties of WSTi3515S burn-resistant titanium alloy such as the elastic properties and thermal properties were measured and analyzed in different conditions. The results show that both the Young＇s modulus and shear modulus of WSTi3515S alloy decrease slightly with the temperature increasing at the tested temperature range. The Poisson＇s ratio of WSTi3515S alloy is around 0.36. However, the thermal properties such as the specific heat, thermal diffusivity, thermal conductivity and thermal expansion increase with the temperature increasing, which results from the strengthening of lattice heat vibration at elevated temperature. And the room temperature density of WSTi3515S alloy is 5.295 gácm^（-3）.