A novel lightweight, radiation-shielding Mg-Ta-Al layered metal-matrix composite (LMC) was successful designed by doping the extremely refractory metal (Ta) into Mg sheets. These Mg-based LMCs sheets shows excellent radiation-dose shield effect, about 145 krad·a⁻¹, which is about 17 times of traditional Mg alloy, while its surface density is only about 0.9 g·cm⁻², reducing by 60% than that of pure Ta. The quantitate relationship between radiation-dose and the materials’ thickness was also confirmed to the logistic function when the surface density is in the range of 0.6–1.5 g·cm⁻². Meantime, the rolling parameters, interface microstructure and mechanical properties in both as-rolled and annealing treated samples were evaluated. The sheets possess a special dissimilar atoms diffusion transitional zone containing an obvious inter-diffusion Mg-Al interface and the unique micro-corrugated Ta-Al interface, as well as a thin Al film with a thickness of about 10 µm. The special zone could reduce the stress concentration and enhance the strength of Mg-Ta-Al LMCs. The interface bonding strength reaches up to 54–76 MPa. The ultimate tensile strength (UTS) and yield strength (TYS) of the Mg-Ta-Al sheet were high to 413 MPa and 263 MPa, respectively, along with an elongation of 5.8%. The molecular dynamics (MD) analysis results show that the two interfaces exhibit different formation mechanism, the Mg-Al interface primarily depended on Mg/Al atoms diffusion basing point defects movement, while the Ta-Al interface with a micro-interlock pining shape formed by close-packed planes slipping during high temperature strain-induced deformation process.

In this study, we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr (wt%) alloy with high strength-ductility synergy by combined processes of hot extrusion, hot rolling and ageing. This alloy exhibits an excellent strength-ductility balance (UTS of 345 ± 2.0 MPa, TYS of 301 ± 5.0 MPa and EL of 9.2 ± 1.9%), which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy. A long-range chain-like structure consisting of β^′ phase, β_H phase, β_M phase and zig-zag atomic columns is observed for the first time in the studied alloy. The combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries, and makes the deformed grains dominate in the alloy strengthening. Under this circumstance, the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains, which plays a key role in the concurrent strengthening and toughening of the alloy. The present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.