High Temperature Creep Behavior Of Thermal Stability And TC11 Titanium Alloy

With high specific strength, good corrosion resistance and excellent high temperature properties, TC11titanium alloy is a two phase heat-strong alloy of Ti-Al-Mo-Zr-Si system. TC11alloy is mainly used in aeroengine compressor parts, such as blade, plate parts, drum and axial, etc. In this paper, TC11alloys were systematically investigated by means of optical microscope, X-ray diffraction instrument, scanning electron microscope, transmission electron microscope, mechanical properties testing machine and tensile creep machine. The main contents and conclusions are as followings:(1) Tensile mechanical properties at room temperature of TC11titanium alloy were tested after long time thermal exposure under500℃The results showed that:tensile strength slightly increased and plasticity decreased obviously, as the extension of exposure time, the plasticity decrease trend slows down, after thermal exposure for400h, tensile strength σb was improved by30MPa and reduction of area Ψ was reduced by11.5%.(2) The high temperature creep behavior of TC11titanium alloy under different heat treatment conditions was studied. The results showed that:the creep performance of TC11titanium alloy is best under the condition of970℃/1h/AC+530℃/6h/AC heat treatment process, alloy creep resistance deteriorated as the extension of aging time under the aging temperature of530℃.(3) The high temperature tensile creep curve of TC11titanium alloy showed that:creep deformation, creep rate increased and steady-state creep time was shortened as the creep temperature and creep stress increased.(4) The high temperature creep behavior of TC11titanium alloy under different creep conditions was studied. Creep stress exponent: T=450℃σ-350～450MPa, n=0.96; T=500℃σ=300～450MPa, n=3.3; T=550℃σ=300～350MPa, n=5.2; T=550℃σ=400-450MPa, n=1.5. Creep apparent activation energy:Qc=144KJ/mol under experimental condition.(5) The creep deformation of TC11alloy in the range of450～500℃、300-450MPa was mainly relied on dislocation slip, creep rate was controlled by dislocation climp. Creep deformation was mainly relied on diffusion, creep rate was controlled by dislocation slip under the creep condition of550℃,300-350MPa. Creep deformation was mainly relied on dislocation slip, diffusion and grain boundary slip, creep rate was controlled by double mechanisms of dislocation climp and diffusion under the creep condition of550℃,400～45OMPa.(6) There were a2and silicide precipitated of TC11titanium alloy in the process of high temperature creep. Precipitation opposed the motion of dislocation, improved alloy creep resistance strength. Si of solid solution state and precipitation state both had strengthening effect on creep resistance, but the former was more obvious.