【摘要】 研究了预变形对近β钛合金Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe (质量分数,%)在时效处理中相变、微观组织及强化响应的影响。结果表明,合金经预变形后再进行时效处理可以获得明显细化的α相与更好的时效强化效果。由于中间相O’、ω和O"的形成抑制了长程应力诱导马氏体相变机制和机械孪晶,合金变形主要是通过位错滑移机制。预变形过程中会产生大量晶格缺陷,随着预变形量的增大,位错数量密度逐渐上升。这些由预变形产生的晶格缺陷会在时效初期部分湮灭,但是仍然能够促进α相析出,实现α相细化。与未预变形的样品相比,预变形量为5%的样品在600℃时效后α相的平均宽度会下降57%,而且数量密度由7.0±1 laths/μm~2上升至22.0±3laths/μm~2。当预变形量较大时,如12%和20%,会形成板条状的α相,这说明钛合金经预变形后再时效处理可以获得细化的α相与更好的强化效果。更多还原

【Abstract】 The influence of pre-deformation on phase transformations,microstructures and hardening response in near β Ti alloy Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe(wt%) during aging treatment was studied.The results show that obvious a phase refinement and stronger age hardening effect can be achieved when the alloy is slightly deformed before aging treatment.Because the formation of intermediate phases(O’,ω and O") suppresses long-range stress induced martensitic transformation and mechanical twinning,the alloy is mainly deformed via dislocation slipping during loading.Large numbers of crystal defects are generated during predeformation.With increasing the pre-deformation,the number density of dislocations increases gradually.These crystal defects generated by pre-deformation may partly annihilate upon early aging,but the precipitation of a can also be promoted,resulting in refined a precipitates.In the sample with 5% pre-strain,the average thickness of a precipitates decreases by 57% after aging at 600℃compared with the sample without pre-strain,and the number density increases from 7.0±1 laths/μm~2 to 22.0±3 laths/μm~2.Some platelet-shaped α phases form when the samples experience comparably large pre-strains such as 12% and 20%.It proves that the refined α precipitates and better hardening effect can be achieved by pre-deformation plus aging treatment for titanium alloy.更多还原