Investigations of PMMCs laminates with regulatable thickness ratio: Microstructure, mechanical behavior and fractural mechanism

Abstract

Laminates composed of varied thickness of Mg–Zn–Y alloy (ZW31) layers and (10 μm 15 vol %) SiCp/AZ91 composite (PMMCs) layers were fabricated by hot extrusion and rolling in the present work. Then, the microstructure and mechanical properties of the laminates were investigated by adjusting the thickness ratio between the ZW31 layer and the PMMCs layer. The results show that compared with the monolithic PMMCs, the PMMCs laminate has good rolling formability. Increasing the thickness ratio not only significantly improves the tensile elastic modulus of the laminate, but also enhances the bending strength and tensile strength under the same strain at the expense of ductility. During the rolling process, the ZW31 layer has a significant effect on alleviating the stress concentration and coordinating the deformation of the PMMCs layer. With the increasing thickness ratio, the thickness of the ZW31 layer decreases while that of the PMMCs layer increases, which accelerates the stress concentration at the layered interface. Grain refinement happens at the interface layers between alloy and composite. The fracture behavior of the laminate depends on the thickness ratio and layered structures containing different grain sizes, which directly affects the stress distribution and the initiation and propagation of cracks in the laminate.