Interface-engineered Al-Zn-Mg-Cu alloys with Sc/Zr-assisted high-ratio TiB2 refinement for enhanced mechanical performance
Dasheng Wei, Chengyuan Wang, He Li, Weitao Zhao, Maowen Liu, Yuanyuan Lu, Chaoli Ma, Ruixiao Zheng
Abstract
In-situ synthesized TiB 2 particles serve as effective heterogeneous nucleation sites for refining grain size of aluminum (Al) alloys. However, excessive TiB 2 content induces self-agglomeration, thereby diminishing the grain refinement efficacy on the Al matrix. Here, we demonstrate that trace additions of Sc/Zr could effectively refine TiB 2 particles, mitigating agglomeration at elevated TiB 2 concentrations. The refinement of TiB 2 particles subsequently enhances their grain refinement efficacy on the Al matrix. As a result, Sc/Zr microalloying improves ultimate tensile strength of as-cast TiB 2 /Al-Zn-Mg-Cu alloys by 51% and elongation by 91%. Detailed electron microscopy analysis reveals that Sc/Zr microalloying forms nanoscale L1 2 -structured Al 3 (Sc,Zr) precipitates with ultra-low lattice misfit to α-Al, enabling coherent α-Al/Al 3 (Sc,Zr)/TiB 2 multi-interfaces for efficient heterogeneous nucleation and grain refinement. The Al 3 (Sc,Zr) can simultaneously pin grain boundaries and suppress recrystallization. The synergetic effects of Sc/Zr and TiB 2 on the microstructure and mechanical properties of the Al-Zn-Mg-Cu alloys were systematically discussed.