Microstructural regulation, work hardening and fracture behavior of Tip reinforced Mg-xGd-2Y-3Zn (x=5, 7, 9 wt.%) composites

In this work, Tip/Mg-xGd-2Y-3Zn (x=5, 7, 9wt.%, Tip/GWZx23) composites were fabricated using semi-solid stirring casting and hot extrusion. The Tip/Mg laminar-like configuration was regulated by Gd content. The effect of Tip/Mg laminar-like configuration on the microstructure, mechanical properties, work hardening and fracture behavior of Tip/GWZx23 composites was thoroughly studied. The results revealed that the Tip elongated along the extrusion direction (ED) after extrusion and formed Tip/Mg laminar-like configuration with the Mg matrix. With the increase of Gd content, the hardness of the matrix increased, which was beneficial to the elongation of Tip. The elongation of Tip reduced its hardness value, released the stress and promoted the DRXed grain refinement. The refined grain enhanced the ability of grain boundaries to absorb dislocations and improved the recovery effect. Furthermore, the formation of Tip/Mg laminar-like configuration induced back stress strengthening at the Tip/Mg interface, enhancing the work hardening rate of the Tip/GWZx23 composites. The Tip/Mg laminar-like configuration changed the strain distribution and the strain was transferred from the Tip sharp corner to the elongated Tip, which was effectively alleviates stress concentration at the Tip/Mg interface and inhibited crack propagation.