Mechanical Properties Of Twinning/slip Type Ti-10Mo-1Fe/3Fe Multilayered Alloys Under Pre-deformation And Aging

β titanium alloys exhibit extensive application prospects in fields of aerospace,biomedical materials and marine engineering due to their high specific strength,low elastic modulus,good biocompatibility,{332}<113> twinning induced plasticity(TWIP)and α’martensitic transformation induced plasticity(TRIP)effect.However,the strength of β-type titanium alloys can be enhanced by means of traditional dislocation strengthening method but ductility is reduced,which limits the application range of them.In the previous investigation,the strength-ducility tradeoff was improved through pre-strain induced {332}<113> twinning and subsequent ω phase precipitation in Ti-15 Mo alloy.Ti-10Mo-1Fe/3Fe multilayered alloys which deformed via twinning/dislocation slip deformation were also found to exhibit good combination of strength and ductility.However,it is not clear whether the combination of pre-strain and aging effect can improve the strength-ducility tradeoff of Ti-10Mo-1Fe 、Ti-10Mo-3Fe alloys as well as the Ti-10Mo-1Fe/3Fe multilayered alloys with twinning/slip deformation and ω phase precipitation.In this paper,the effect of pre-strain induced twin/dislocation and subsequent precipitation of isothermal ω phase was investigated in Ti-10Mo-1Fe/3Fe multilayered alloys.Ti-10Mo-1Fe and Ti-10Mo-3Fe alloys were also investigated as comparison materials.Due to the precipitation of brittle ω phase,the Vickers hardness of Ti-10Mo-1Fe and Ti-10Mo-3Fe alloys was continuously increased when the aging temperature was increased from 200 ℃ to400 ℃.High yield strength of 712 MPa and larger uniform elongation of 10% were achieved in Ti-10Mo-1Fe alloy after 5% pre-strain and subsequent aging at 200 ℃ for 1 h,while no apparent improvement was observed in Ti-10Mo-3Fe alloy after the same processing method with yield strength of 981 MPa and negligible uniform elongation(0.2%).At the same pre-strain amount,two alloys exhibited brittle fracture mode when the aging temperature was increased to 300 ℃.Similarly,for Ti-10Mo-1Fe/3Fe multilayered alloys,the Vickers hardness was also continuously increased as increasing aging temperature from 200 ℃ to 400 ℃.Furthermore,the Vickers hardness of Ti-10Mo-1Fe layer was higher than that of Ti-10Mo-3Fe layer at the same aging temperature.After 5% pre-strain and subsequent aging at 200 ℃ for 1 h,Ti-10Mo-1Fe/3Fe multilayered alloys exhibited good combination of strength and ductility(the yield strength of 960 MPa,the uniform elongation of 8%)after 5% pre-strain and isothermal aging at 200 ℃ for 1 h.At the same pre-strain amount,Ti-10Mo-1Fe/3Femultilayered alloys exhibited brittle fracture mode when the aging temperature was increased to 300 ℃.