Synergistic Regulation and Strengthening Mechanisms of Sc/Zr Microalloying and Friction Stir Processing in TiC/ZL205A Composites

Abstract

To overcome the critical bottlenecks in the current research on particle reinforced aluminum matrix composites, this study exploits the synergistic effects of Sc/Zr microalloying and friction stir processing (FSP) to refine the microstructure of composite materials, thereby enhancing their overall mechanical properties. The SEM and EBSD analysis results indicate that the introduction of Sc and Zr elements, in conjunction with FSP, results in substantial grain refinement of the composite and notably enhances the uniform distribution of reinforcing particles within the matrix. Moreover, following FSP, the dislocation density and the number of low-angle grain boundaries in the composite are markedly increased, which contributes positively to the enhancement of the material's mechanical properties. TEM analysis reveals that TiC particles show no agglomeration and form a semi-coherent interface with the aluminum matrix through direct atomic bonding. The L12-Al3(Sc, Zr) precipitate exhibits a fully coherent interface with the aluminum matrix. The θʹ precipitate size decreased from ~75 µm to ~39 µm, accompanied by a significant improvement in dimensional uniformity. This study carried out a systematic investigation into the strengthening and toughening mechanisms.

Keywords: aluminum matrix composite, Microalloying, Friction stir processing, microstructure, Mechanical property