Study on the evolution pattern of grain orientation and misorientation during the static recrystallization of cold-rolled Mg-Zn-Gd alloy

Abstract

The recrystallization process has been reported to be responsible for the formation of non-basal texture in Mg-RE and Mg-Zn-RE alloy. The microstructure, macro-texture, grain orientation and misorientation evolution have been characterized during annealing at 150–480 °C to understand the evolution of non-basal texture from a cold-rolled elliptical annular texture to a TD-split texture with double peaks tilting away from ND to TD. The results show that static recrystallization (SRX) begins to take place at 200 °C, and an almost fully recrystallized microstructure is obtained at 300 °C and obvious grain growth from 300 °C to 400 °C. Meanwhile, during the SRX process, the R texture component disappears while the T (−45°) texture component is enhanced, turning into the TD-split texture, and the specific crystal direction parallel to RD rotates from [011¯0] to [1¯21¯0]. The misorientation relationship between SRXed grains and the matrix depends on the nucleated location based on the electron backscattered diffraction (EBSD) results. Furthermore, most SRXed grains formed by different ways have T orientation. During grain growth period, several special grain boundaries are preserved. Meanwhile, coarse grains have T orientation and [1¯21¯0]//RD orientation, showing a preferred grain growth tendency. It is referred that the texture evolution during SRX is mostly related to preferred grain growth which may be caused by the special misorientation or/and the segregation of Zn and Gd solute atoms on special grain boundaries.