Abstract:Comparative analysis of the differences in tensile strength and impact toughness between the TC25 alloy and TC25G alloy of Ti-Al-Zr-Sn-Mo-W-Si series titanium alloys was carried out, and the root causes of the differences in impact toughness between the two alloys and the alloy strengthening mechanism were elucidated through the observation of the SEM fracture morphology and the analysis of the TEM microscopic deformation mechanism. The results show that the precipitated phase in the impact fracture of TC25G alloy is ZrSi or TiZrSi compounds, which plays the role of second-phase reinforcement and is conducive to the enhancement of the alloy strength, and the precipitates are conducive to the extension of impact cracks, thus reducing the impact toughness of the alloy. In the microstructure of the impact fracture of TC25 alloy, the cracks generally extend along the primary α phase boundary, so the TC25 alloy crack extension path longer. While TC25G alloy cracks cross through the primary α phase. Thus, the TC25 alloy has higher impact toughness. TEM observations show that the number of dislocation slip traces and dislocation plugging in TC25G alloy is significantly higher than that in TC25 alloy. The presence of a large number of plugged dislocations in the vicinity of the precipitates in TC25G alloy results in significant strengthening, leading to a higher strength of the alloy.