Design, preparation, microstructure and mechanical property of the lightweight radiation-shielding Mg-Ta-Al composites basing differential temperature hot rolling

Abstract

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.

Keywords

• Dissimilar metals composites
• Mg based alloys
• Radiation shielding
• Hot rolling
• Lightweight