Study On Deformation Mechanism Of Ti-10Mo-1Fe Alloy

Titanium alloy has been widely used in aerospace,energy,chemical and biomedical fields due to its high specific strength,significant corrosion resistance and better biocompatibility.Ti-Mo-based titanium alloy have mechanical property matching and excellent machining performance due to its special plastic deformation mechanism at room temperature.After various heat treatments,the initial microstructures of the titanium alloys before deformation are different,resulting in the difference between deformation mechanism at room temperature.Herein,the microstructure evolution of a near?titanium Ti-10Mo-1Fe alloy deformed under room temperature was analyzed.The influence of grain size,the initial microstructure before deformation and the stress loading method on the deformation mechanism and mechanical properties were studied.The main deformation mechanism of alloy after solution-treated followed with water cooling(WQ alloy)is{332}<113>twinning and stress-induced martensite?"phase.The stress-induced?phase,{112}<111>twinning,dislocation slip can also be detected in the deformed samples.The yield strength of the WQ alloy is acceptable,and the elongation is excellent.The excellent performance of the elongation is mainly due to the dynamic refinement of grain by the generation of{332}<113>twinning.The tensile/compressive strength of the alloy solution-treated above T_?followed with water quenching is affected by the grain size and the appearance of the{332}<113>twinning.When solution treated at 810?and 840?,the grain were fine enough to improve the strength,while the average grain size for these samples was not suitable for the formation of{332}<113>twinning.On the contrary,when solution treated at 900?,the contribution of grain refinement was small while the strengthening effect of{332}<113>twinning was remarkable.The strengthening of grain size and twinning matches well while the alloy solution-treated at870?.Therefore,the compression/tensile strength of the alloy is higher than solution-treated at other temperatures.Compared with the alloy solution-treated above T_?,the strength of the alloy increases and the elongation decreases when solution-treated at780?.The existence of primary?phase makes the distribution of intergranular twinning more unequal.The compression cracks can be observed in the 45°direction at the boundary between primary?phase and?phase under serious deformation.The deformation mechanism of the tensile alloy is similar to the compression one.The volume fraction of the stress-induced?"martensite is higher,and the coexistence of various deformation mechanisms is more complex than the compression alloy.Compared with the WQ alloy,the strength of the alloy increases and the elongation decreases when solution-treated above T_?followed with air cooling(AC alloy).Because a large number of nanoscale isothermal?phase precipitated in the?grains during air cooling,which can improve the strength and hardness of the alloy.However,the isothermal?phase also suppressed the TWIP/TRIP effect in the alloy.The deformation mechanism of the alloy solution-treated above T_?followed with air cooling(AC alloy)were{332}<113>twinning and dislocation slip.The mechanical properties of the alloy are affected by combination of deformation modes(twinning and dislocation slip).Compared with the water quenching samples,the volume fraction of the{332}<113>twinning is lower,the width of the twinning is larger,the distortion of twinning boundary under severe deformation is more serious,and the dislocation slip makes more contribution to the deformation.The stress-induced?"phase,the stress-induced?phase and{112}<111>twinning can also be detected in the deformed air cooling samples.The strength and the elongation of the alloy solution-treated above T_?followed with furnace cooling(FC alloy)were lower than that for WQ alloy.Because more than 52%of?_s phase precipitated in the?phase.It is evident that the?domain size decreased because the formation of?can separate the?grains and reduce the area of the matrix to the nanometer level.Consequently,the formation of twinning and stress-induced?"martensite will be difficult.The strengthening effect of?_s phase in the FC alloy is weaker than that of the?phase in the AC alloy,and is not as good as the strengthening effect of twinning in the WQ alloy,resulting in the lower compressive strength of the FC alloy.