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To address the demand for lightweight, high-performance Al-Si-Mg alloys in aerospace and automotive industries, this work proposes a novel synergistic strengthening strategy by combining rare-earth Y microalloying and in situ synthesized ZrB2 nanoparticles to construct a hybrid reinforcement architecture. The effects of Y-ZrB2 additions on the microstructure, crystallographic orientation evolution, and mechanical properties of Al-Si-Mg alloys were systematically investigated via XRD, SEM, EBSD, and tensile/hardness tests. Results show that compared with the base alloy and single-modified alloys, the co-addition of Y and ZrB2 simultaneously enhances mechanical properties and optimizes grain structure. The optimal comprehensive performance is achieved at 0. 3 wt. % Y + 2 wt. % ZrB2 after T6 heat treatment, with ultimate tensile strength of 332. 87 MPa, yield strength of 271. 35 MPa, elongation of 16. 24%, and Vickers hardness of 153. 9 HV. Phase analysis and SEM-EDS confirm a synergistic coupling relationship between Y-rich phases and ZrB2 nanoparticles. EBSD characterization reveals that Y-ZrB2 modification has negligible effect on the morphology and crystallographic orientation stability of primary α-Al grains, but effectively regulates the lattice rotation, texture redistribution, and growth behavior of eutectic Si. At the optimal composition, the fraction of high-angle grain boundaries (HAGBs) reaches a maximum of 34. 3%. Furthermore, the synergistic effect significantly increases the geometrically necessary dislocation (GND) density and reduces the Schmid factor of the dominant 111⟨110⟩ slip system, thus enhancing dislocation strengthening and plastic deformation resistance. This work clarifies the intrinsic strength-ductility synergy mechanism of Y-ZrB2 co-modified Al-Si-Mg alloys, paving a new pathway for the development of advanced lightweight aluminum alloys.
Yue et al. (Sun,) studied this question.