In this work,the 90° clock rolling and the uni-directionally rolling processes at high temperature were carried out on the near β-type Ti-5.2Mo-4.8Al-2.5Zr-1.7Cr titanium alloy cutting from an ingot,respectively.The corre-sponding microstructures were quantitatively characterized,and its effect on the dynamic mechanical properties and fracture mechanism were emphatically investigated.It was found that after 90° clock rolling,the micro-structure composed of equiaxed primary α phase(αp)with an average size of about 2 μm and the β transformed regions containing the acicular secondary α phase(αs)with an average thickness of about 50 nm and the separatedβ phase was obtained.However,in the uni-directionally rolled titanium alloy,no acicular αs was observed,and the corresponding microstructure consisted elongated lamellar α phase(average thickness:about 1.3 μm),few equiaxed α phase(average grain size:about 300 nm)and the inlaid β phase.The microstructural difference of the hot-rolled titanium alloys was closely related to the deformation process.Moreover,a great number of αp and αs in the 90° clock rolled titanium alloy effectively enhanced the strength,and the dynamic compressive strength reached to 1730 MPa.Furthermore,equiaxed αp was conducive to the homogeneous deformation,which coun-teracted the localized deformation caused by acicular αs to a certain extent and made the 90° clock rolled titanium alloy exhibit an acceptable critical fracture strain of about 10.5％.Moreover,the fracture microstructures showed that the main failure mode of the 90° clock rolled and the uni-directionally rolled titanium alloy were ductile fracture and brittle fracture,respectively.

Chinese Weapons Science Academy Ningbo Branch,Ningbo,315103,China;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

[1]Xinjie Zhu;Qunbo Fan;Guxin Zhou;Duoduo Wang-.Influence of hot-rolling on the microstructure and mechanical properties of a near β-type Ti-5.2Mo-4.8Al-2.5Zr-1.7Cr alloy)[J].自然科学进展·国际材料（英文）,2022(04):504-509

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