The strength-elongation to fracture(εf)trade-off and low strain hardening rate have been a longstanding dilemma in titanium alloys.In this work,we innovatively manufactured a novel Ti-6Mo-3.5Cr-1Zr alloy via the introduction of a stress-induced strengthening phase into the material.Stress-induced ω(SIω)phase transformation was expected to replace the α"martensitic transformation that resulted in the low yield strength of titanium alloys.The obtained alloy exhibited an extremely high strain hardening rate of up to～1820 MPa.The true peak tensile strength and εf reached～1242 MPa and～40％,respectively.The intrinsic mechanisms underlying the simultaneous improvement of strength and ductility of the mate-rial were systematically investigated via in-situ and ex-situ characterizations.In-situ electron backscatter diffraction(EBSD)/digital image correlation(DIC)results showed that SIω phase transformation domi-nated the early stage of plastic deformation(1.5％-3％)and promoted the strain partitioning between the stress-induced bands and β matrix.Subsequently,the formation of{332}<113>β twins and co twins was observed via ex-situ EBSD.In-situ transmission electron microscopy results revealed that dislocation pile-up(DPU)occurred at the SIω/β interface.The coupling effects associated with the transformation induced plasticity(TRIP),twinning induced plasticity(TWIP),and DPU mechanisms contributed to the enhanced strength and εf of the designed titanium alloy.

Kai Chen;Qunbo Fan;Jiahao Yao;Lin Yang;Shun Xu;Wei Lei;Duoduo Wang;Jingjiu Yuan;Haichao Gong;Xingwang Cheng

National Key Laboratory of Science and Technology on Materials Under Shock and Impact,School of Materials Science and Engineering,Beijing Institute of Technology,Beijing 100081,China;Beijing Institute of Technology Chongqing Innovation Center,Chongqing 401135,China

材料科学技术（英文版）

[1]Kai Chen;Qunbo Fan;Jiahao Yao;Lin Yang;Shun Xu;Wei Lei;Duoduo Wang;Jingjiu Yuan;Haichao Gong;Xingwang Cheng-.Composition design of a novel Ti-6Mo-3.5Cr-1Zr alloy with high-strength and ultrahigh-ductility)[J].材料科学技术（英文版）,2022(36):276-286

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