Mechanical Properties Regulation and Mechanism of TC11 Titanium Alloy Under Novel Deep Cryogenic-Electroshock Composite Treatment

YL Song and JH Hu and SL Guo and JH Liu and J Lu and JJ Su and L Hua, METALS AND MATERIALS INTERNATIONAL (2025).

DOI: 10.1007/s12540-025-02089-1

This study proposes a novel deep cryogenic-electroshock composite treatment (DCT-EST) to enhance the strength-ductility synergy of TC11 titanium alloys. Through a comparative analysis of uniaxial tensile tests, it is found that, compared to the original specimen (ORI), the mechanical properties of the treated specimen are significantly improved after the DCT-EST: while the average tensile strength remains unchanged (with a change rate of less than 1%), the average engineering strain at fracture and the strength-ductility product have significantly increased by 20.1% and 20.7%, respectively. Multiscale microstructural characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron back-scattered diffraction (EBSD), and transmission electron microscopy (TEM). The results indicate that DCT promotes short-range diffusion of Mo atoms, thereby facilitating the partial phase transformation of beta phase -> metastable beta phase -> alpha(s) phase. This leads to grain refinement from 2.24 mu m to 2.03 mu m and an increase in dislocation density from 5.97 x 10(14) m(-)(2) to 7.14 x 10(14) m(-)(2), resulting in a synergistic improvement in both strength and ductility of the material. Subsequent EST reduces the dislocation density to 6.88 x 10(14) m(-)(2) and homogenizes stress distribution, further enhancing the ductility of TC11 titanium alloys. Finally, molecular dynamics simulation revealed the evolution of dislocations (1/3 < 1-100 >) in TC11 titanium alloy under DCT-EST conditions and the directional migration process of Mo atoms in the beta phase. Combined with theoretical analysis and a multi-field microstructural evolution model, the cooperative regulation mechanism of the DCT-EST process on the multiphase and multiscale strength-ductility synergy of titanium alloys was elaborated in detail.

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