Abstract

In this paper, the multi-scale particles (Mg12La, Al2Gd, and TiB2) were successfully introduced to Mg-9Gd alloy in casting method. With the introduction of multi-scale particles, the microstructure of as-cast alloys transforms from dendrites into equiaxed crystals. Compared to single-sized submicron-Mg12La particles and bimodal micron-Al2Gd + nano-TiB2 particles, the multi-scale particles (Mg12La, Al2Gd, and TiB2 particles) show the best grain refining effect. The average grain size reduced from 299-734 μm in Mg-9Gd alloy to 44.3–61.4 μm in 6.1 wt% (TiB2-Al2Gd)/Mg-9Gd-0.5La composite. The YS (211 MPa) and UTS (263 MPa) of the 6.1 wt% (TiB2-Al2Gd)/Mg-9Gd-0.5La composite were 42.6 % and 15.9 % higher than those of the Mg-9Gd alloy (148 MPa and 227 MPa), respectively. The excellent strength of the extruded composite is attributed to the synthetic strengthening effects of Mg12La, Al2Gd, and TiB2 particles.