摘要：To study the relationship between the microstructure and tensile properties of the novel metastable β titanium alloy Ti-5.5Cr-5Al-4Mo-3Nb-2Zr,a heat treatment process of ABFCA(solid solution in α+βregion with subsequent furnace cooling followed by aging treatment finally)was designed,by which α phases of different sizes can be precipitated in the β *** results show that the microstructure obtained by this heat treatment process is composed of primary α(α_(p))phase,submicro rod-like α(α_(r))phase and secondary α(α_(s))*** alloy with multi-scale α phase has an excellent balance between strength and *** elongation is about 18.3% at the ultimate tensile strength of 1125.4 *** relationship between the strength of the alloy and the α phase was *** strength of the alloy is proportional to the power of‒1/2 of the average spacing and width of α *** α_(s) phase with a smaller size and phase spacing can greatly improve the strength of the alloy by hindering dislocation *** transmission electron microscope analysis shows that there is a large amount of dislocation accumulation at the α/β interfaces,and many deformation twins are found in the α_(p) phase after tensile *** the dislocation slip is hindered,twins occur at the stress concentration location,and twins can initiate some dislocations that are difficult to ***,the plastic strain is distributed uniformly among the α_(p),α_(r),α_(s) phases and β matrix,thereby enhancing the ductility of the alloy.