Effect of Al and Gd Solutes on the Strain Rate Sensitivity of Magnesium Alloys

Pure magnesium and two binary alloys, Mg-1 wt pct Al and Mg-1.4 wt pct Gd, have been prepared with comparable grain sizes and textures. The alloys have been tensile tested at various strain rates and temperatures to examine the strain rate sensitivity (SRS). It has been found that Mg and Mg-Al show increasing SRS with increasing deformation temperatures. The Mg-Gd alloy showed decreasing SRS with increasing deformation temperatures and exhibited a negative SRS at 200 A degrees C and 250 A degrees C. Above these temperatures, the SRS returned to a positive value. The elongation to fracture was not effected by the SRS, and it has been concluded that for the alloys and conditions examined, the influences of mechanical twinning and dynamic recrystallization dominate the elongation behavior, rather than the SRS.