Study on the Strength-Plasticity Enhancement Mechanism of the Sicp/Fe Symmetric Gradient Structure and Alloying in the High-Particle-Content Layer

Abstract

The construction of heterogeneous structures is an effective method to achieve a favorable balance between material strength and ductility. By controlling the silicon carbide (SiCp) particle content, Fe-based layered composites with a symmetric gradient structure were prepared using spark plasma sintering (SPS) and subjected to hot rolling to investigate the microstructural evolution and mechanical performance of each layer. The results show that the gradient distribution of SiCp content leads to different grain sizes across the layers. The interfaces between layers were relatively smooth, with no defects such as cracks resulting from interface stress concentration observed. The formation of an amorphous layer between SiCp and Fe, as well as FeSiO3 crystalline products, promoted strong bonding between the two. In terms of mechanical properties, the gradient distribution of SiCp content resulted in a symmetric gradient in Vickers hardness values across the material. Compared with pure Fe, homogeneous 3% SiCp/Fe, and 10% SiCp/Fe composites, the SiCp/Fe symmetric gradient structure exhibited higher hardness without a significant reduction in plasticity. After hot rolling, the yield strength of the SiCp/Fe symmetric gradient structure reached 912.45 MPa, with an elongation of 7.67%, demonstrating the synergistic effect of the heterogeneous layered structure on enhancing both strength and plasticity. Additionally, due to the high localized stresses during the hot rolling process, SiCp in the 10% SiCp/Fe layer was decomposed and reacted with the Fe matrix to form Fe-C and Fe-Si compounds. The ultrafine grains in this layer also contributed to the high strength of the SiCp/Fe symmetric gradient structure.

Keywords: Heterogeneous structure, Gradient structure, Silicon carbide particles, Interface products, Particle decomposition