The Deformation Behavior, Microstructure and Mechanical Properties of Cast and Extruded Mg-1Mn-xNd (wt%) at Temperatures between 50°C and 250°C

Abstract

The tensile deformation behavior of as-cast and cast-then-extruded Mg-1Mn-1Nd(wt%) and Mg-1Mn-0.3Nd(wt%) alloys was studied by performing in-situ tests inside a SEM. A slip/twin trace analysis technique was used to identify the distribution of the deformation systems. Cast-then-extruded Mg-1Mn-1Nd(wt%) exhibited superior elevated-temperature strength retention compared to cast-then-extruded Mg-1Mn-0.3Nd(wt%). Basal slip and extension twinning were observed in the as-cast Mg-1Mn-1Nd(wt%) and Mg-1Mn-0.4Nd(wt%) alloys deformed at 50°C. In cast-then-extruded Mg-1Mn-1Nd(wt%), basal slip, prismatic slip, and pyramidal <c+a> slip were active at all temperatures. In cast-then-extruded Mg-1Mn-0.3Nd(wt%), at lower temperatures, twinning dominated the deformation and no non-basal slip activity was observed. The extent of twinning decreased with increasing temperature and basal slip was the major deformation mode at 150–250°C in both cast-then-extruded materials. The estimated CRSS ratio of extension twinning with respect to basal slip in Mg-1Mn-1Nd(wt%) was close to unity, suggesting that the addition of Nd results in an increase in the CRSS of basal slip.