Microstructural analysis and mechanical properties of AZ31 magnesium alloy prepared by alternate extrusion (AE)

Abstract

One of the goals in the field of extrusion technology is to simplify the process and increase shear deformation in order to improve the grain refining capacity. This article innovatively tries to design a split punch structure and makes them alternate downward loading, so alternate extrusion (AE) method is proposed. Optical microscopy (OM), scanning electron microscope (SEM), and transmission electron microscopy (TEM) are employed to characterize the microstructure of AZ31 magnesium alloy during AE. Compared with the conventional extrusion (CE) under the same conditions, the microscopic experiment results show that the grain is more refined and the microstructure is more homogeneous. AE produces a large number of different direction dislocations and entangle with each other. The reasons for the above phenomenon are the plastic zone’s range of AE significantly increased. And between interface of double punch and die form a range of shear zone, which provides fully refined grain source power in the extrusion process. The tensile test results show that the mechanical properties of AE were better than CE, which is consistent with the results of our microscopic experiment results.