Deformation behavior of Mg-5Y-2Nd-0.5Zr alloys with different Sm additions

Herein, we studied the microstructural evolution and deformation behavior of aged Mg-5Y-2Nd-xSm-0.5Zr (x = 1, 3, and 5 wt%) alloys during uniaxial compression at room temperature by transmission electron microscopy and quasi-in-situ electron backscatter diffraction techniques. The microstructures of Mg-5Y-2Nd-xSm-0.5Zr alloys are refined by the addition of Sm, with more occurrences of Mg(Nd, Sm) precipitates. The average grain size decreased significantly with increasing Sm content, from 80.4 mu m (1 wt% Sm) to 64.8 mu m (3 wt% Sm) and 50.0 mu m (5 wt% Sm). The Mg-5Y-2Nd-3Sm-0.5Zr alloy exhibited a maximum compressive strength of 390.1 MPa and a maximum strain (epsilon) of 0.103 at room temperature; {10-12} tensile twinning and dislocation slips are the main plastic deformation modes of Mg-5Y-2Nd-xSm-0.5Zr alloys during compression at room temperature. A number of < a > and < c + a > dislocations were observed in the aged Mg-5Y-2Nd-3Sm-0.5Zr alloy. The optimized ductility value is attributable to grain refinement; elemental Sm promotes the activation of the non-basal < c + a > slip dislocations and interactions between twins and < c + a > dislocations. The strengthening mechanism mainly includes solid solution, fine-grain, and precipitation strengthening. (C) 2020 Elsevier B.V. All rights reserved.