Analysis of Abnormal Texture and Strengthening Mechanisms of Extruded Mg–Gd–Y–Nd–Zr Alloy

Abstract

The formation mechanism of an abnormal texture with <0001> orientation parallel to the extrusion direction (<0001>//ED) and strengthening mechanisms in the extruded Mg–Gd–Y–Nd–Zr alloy are investigated. When extruded at a ratio of 25, the abnormal texture is accompanied by a completely dynamic recrystallized (DRXed) microstructure, and its intensity increases with increasing extrusion temperature. When the extrusion ratio is reduced to 9, the multiple texture components are formed, accompanied by nonuniform microstructures. Rare-earth (RE) elements segregating at the grain boundary or existing as a secondary phase affect the activation of nonbasal slips and preferential growth of DRXed grains. The formation mechanisms of abnormal texture are completed DRX, the operation of pyramidal <c + a> slip, and growth advantage. The strengthening mechanisms in the extruded Mg–Gd–Y–Nd–Zr alloy mainly include solid solution strengthening, grain boundary strengthening, and precipitate strengthening, among which solid solution strengthening plays a key role. The trade-off between the three strengthening mechanisms results in the stability of the mechanical properties of the extruded Mg–Gd–Y–Nd–Zr alloy under various extrusion conditions.