Abstract:

The Ti_p/ZX60 composites with different Ti_p contents were prepared by semi-solid stirring casting. After extrusion, the microstructure, work hardening and softening behavior of the Ti_p/ZX60 composites were analyzed compared with the ZX60 (Mg-6Zn-0.2Ca) alloy. The results showed that the addition of Ti_p could not only promote the nucleation of dynamic recrystallized (DRXed) grains, but also be propitious to the refinement of DRXed grains. With increasing Ti_p content, the size of DRXed grains decreased accompanied with increasing volume fraction of DRXed grains. As the Ti_p content increased to 15 vol.%, the average size and volume fraction of DRXed grains reached to ~ 0.32 μm and 93.2%, respectively. Besides, both the strength and elongation were improved by the addition of Ti_p. With increasing content of Ti_p, a substantial increase in the strength was achieved with little change in the elongation. However, the elongation decreased sharply when the Ti_p content further increased to 15 vol.%. The addition of Ti_p led to an increase in the work hardening rate, which gradually increased with increasing Ti_p content. However, the softening rate did not demonstrate the same tendency with increasing Ti_p content. Unlike the conventional ceramic particles, the Ti_p can be deformed in coordination with the matrix alloy, which imparted a higher softening rate to the matrix alloy. Even though the softening rate improved as the Ti_p content increased from 5 to 10 vol.%, it dropped deeply as the Ti_p content increased to 15 vol.% owing to the fracture of Ti_p during extrusion.

Key words: Titanium particle content, Particle reinforced magnesium matrix composites, Work hardening, Softening behavior, Mechanical properties