Grain Refinement and Texture Evolution of Mg-1Zn-1Gd Alloy by the Equal Channel Angular Pressing

Abstract:

In this paper, in order to find out the effect of Equal Channel Angular Pressing (ECAP) on the microstructure and texture, as well as dynamic recrystallization (DRX) behavior, Mg-1Zn-1Gd alloy (wt.%) was investigated. The results show that after the equal channel angular pressing at 350℃, the microstructures of these samples is composed of fine recrystallized grains, and there are a large number of homogeneously distributed equiaxed grains in the matrix. Upon 8 passes, the uniform ultra-fine grain structure with an average grain size of 3.6 μm is obtained. The mechanism of the discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) lead to grain refinement. The micro-texture was analyzed through electron backscatter diffraction (EBSD) technique. It is revealed that after 4 passes of ECAP, a strong basal texture is achieved (multiple?random?distribution?~19.76). With the extrusion passes increasing, the grain in the basal planes of extruded alloy billet is mainly elongated along the extrusion direction, the orientation distribution changes from concentrated state to decentralized state. The texture is weakened which the maximum strength is 15.66 mrd. Finally, the texture is also related to the plane anisotropy of the Mg-1Zn-1Gd alloy.

Key words:Mg-Zn-Gd alloy; Equal Channel Angular Pressing; grain refinement; DRX; texture