Dynamic softening mechanism of 2 vol.% nano-sized SiC particle reinforced Al-12Si matrix composites during hot deformation

The hot deformation behavior of the 2 vol.% nano-SiCp/Al-12Si composites prepared by powder metallurgy is complicated due to the simultaneous presence of nano-sized SiC particles and micro-sized precipitated Si particles. In this paper, the isothermal heat compression test and the transmission electron microscope analysis technique were used to analyze the softening mechanism of the 2 vol.% nano-SiCp/Al-12Si composites based on Z parameters and deformation temperature, and the nucleation mechanism of dynamic recrystallization of the 2 vol.% nano-SiCp/Al-12Si composites was analyzed. The results showed that, when LnZ > 55.02, T ≤ 753 K, the cross slip of dislocation was the main softening mechanism; when LnZ < 55.76, T ≥ 733 K, the softening mechanism mainly includes the cross slip, climbing of dislocation, and untangling of three-dimensional dislocation network; when lnZ ≤ 53.65, T ≥ 773 K, the dynamic recovery and dynamic recrystallization were the main softening mechanism of the composites. The dynamic recrystallization nucleation mechanisms of the 2 vol.% nano-SiCp/Al-12Si composites include the sub-grain combination nucleation and grain boundaries bulging nucleation. (paper)