Novel microstructures inducing an excellent combination of strength and elongation in in-situ MgO/AZ31 composites

Abstract

Herein, in-situ MgO particles with novel spatial arrangements were introduced into AZ31 using ball milling and hot extrusion. The MgO particles assemble into a honeycomb-like structure in the three-dimensional (3D) space, and exhibit an adequate interfacial integrity with the magnesium matrix. The grains in MgO-rich zones are refined to approximately 1 μm, and the MgO/AZ31 composites exhibit a bimodal structure consisting of fine-grain and coarse-grain zones. The fine grains exhibit a honeycomb-like arrangement and are filled with the coarse grains, just like a bee pupa-infilled honeycomb. Compared to AZ31, the fabricated MgO/AZ31 composites have an greatly enhanced strength and a slightly improved ductility, displaying an adequate combination of strength and ductility. In particular, the ultimate tensile strength and elongation of 0.75 wt% MgO/AZ31 composites were up to 343 MPa and 18.5%, respectively. The outstanding mechanical properties could be attributed to the novel honeycomb-like structure and in-situ MgO.