Strain-rate sensitivity of Mg–Gd alloys after extrusion and simple shear extrusion

Abstract

Pure Mg and Mg–Gd alloys with 0.5–2 wt-% gadolinium (Gd) were processed by extrusion and simple shear extrusion (SSE). The strain-rate sensitivity (SRS) was investigated by shear punch testing (SPT) at temperatures ranging from 573 to 723 K and for shear strain rates ranging between 0.016 and 0.13 s −1 . The Gd-containing alloys processed by SSE showed small m-values at 573 K, which increased with increasing temperature up to 673 K, and decreased afterwards due to grain growth. The highest SRS index (0.47) was found at 673 K for Mg-2Gd after 4 passes of SSE, coinciding with the finest grain size (2 µm). This implies that the material can behave superplastically via a grain boundary sliding mechanism. This paper is part of a thematic issue on Light Alloys.