Effects of Zn and Li alloying on microstructural evolution and mechanical properties of extruded Mg-1Gd alloys
Jun Zhao, Jinkang Liu, Jun Xu, Bin Jiang, Bin Lei, Yueyang Yuan, Xuejiao Shi, Qinghang Wang
Abstract
Effects of Zn and Li alloying on microstructural evolution and mechanical properties of extruded Mg-1Gd alloys were investigated. The addition of single Zn leaded to significant grain refinement in Mg-1Gd alloy, whereas Li alloying induced remarkable grain coarsening. The average grain sizes of the extruded Mg-1Gd, Mg-1Gd-1.5Zn, Mg-1Gd-1.5Li and Mg-1Gd-1.5Zn-1.5Li alloys were ∼21.9, ∼15.5, ∼35.8 and ∼31.2 μm, respectively. Single Zn alloying significantly improved the yield strength and ductility of the extruded Mg-1Gd alloy. The improvement of yield strength in the extruded Mg-1Gd-1.5Zn alloy were mainly associated with the fine grain size, dispersed fine Mg 3 Zn 3 Gd 2 particles and Zn solute atoms. In addition, the ductility enhancement with single Zn addition was mainly linked to grain refining. However, single Zn alloying resulted in a slightly increase of the yield strength, which was associated with the competitive interplay of texture strengthening and grain coarsening. Further, a striking yield strength enhancement was observed with the synergistic addition of Zn and Li, which was primarily benefited from a strong basal texture, despite grain coarsening. In addition, the reduced ductility of the extruded Mg-1Gd-1.5Li and Mg-1Gd-1.5Zn-1.5Li alloys was ascribed to a combined effect of the enhanced basal texture development and grain coarsening.