Abstract
3 vol% TiB2 nanoparticles were added to an Mg-4Al-1.5Si alloy through semi-solid stirring followed by ultrasonic vibration to refine coarse Mg2Si phases. The effect of the added TiB2 nanoparticles on the size and morphology of the Mg2Si phases as well as the mechanical properties of the magnesium alloy was investigated. The experimental results showed that under the synergistic action of ultrasonic vibration and heterogeneous nucleation of TiB2 nanoparticles, the primary Mg2Si phases were not only refined from coarse dendritic to fine blocky shape but also uniformly dispersed. The morphology of the eutectic Mg2Si phases was transformed from coarse Chinese scripts to fine short strips. The Vickers-hardness, ultimate tensile strength, and yield strength of the obtained composites were increased by 101.8%, 69.8%, and 10.6%, respectively, compared with the matrix alloy, and the elongation was enhanced from 3.2% to 9.2% especially. The fracture mode was transformed from brittle fracture of the untreated Mg alloy to ductile fracture of the composites, indicating that the TiB2 nanoparticles play an effective role in strengthening and toughening Mg-Al-Si alloys. (C) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier