Effects of ECAE temperature and billet orientation on the microstructure, texture evolution and mechanical properties of a Mg–Zn–Y–Zr alloy

Abstract

Single-pass equal channel angular extrusion (ECAE) experiments of an extruded Mg–Zn–Y–Zr alloy with an intense initial basal texture were performed in two inter-perpendicular billet orientations and at 473 and 623 K. The study was aimed to determine the effects of ECAE temperature and billet orientation on the microstructure, texture evolution and mechanical properties of the ECAEed alloy. It was found that the grain refinement achieved through the single-pass ECAE in the Orient-I billet orientation (the normal direction (ND) of the extruded plate parallel with the ECAE exit direction) was more effective than that in the Orient-II billet orientation (the ND of the extruded plate perpendicular to the ECAE exit direction). The average grain sizes after ECAE at 473 K were much smaller than those after ECAE at 623 K. The pole figures of the alloy ECAEed at 473 K showed that most of the basal planes in the Orient-I and Orient-II samples were inclined about 40° and 35°, respectively, with respect to the longitudinal direction of the ECAE extrudate. However, for the alloy ECAEed at 623 K, most of the basal planes were parallel with the longitudinal direction of the ECAE extrudate. It was remarkable that the yield strengths of the alloy ECAEed at 473 K were lower than those at 623 K. The peculiar relationship between ECAE temperature and the mechanical properties of the alloy was ascribed to the texture evolution during ECAE.