RESUMO
Enhancing the mechanical properties of magnesium alloys to meet the urgent need for their lightweight applications in the aerospace field has always been a great challenge. Herein, the effect of Ag on the microstructure and tensile properties of the Mg-2.5Nd-1.0Sm-0.4Zn-0.1Ca-0.5Zr (EK30) alloy prepared by integrated extrusion and equal-channel angular pressing is studied. The microstructure of as-extruded alloys consists of α-Mg grains and the ß phase. The addition of Ag increases the ß-phase content. The ß phase can promote dynamic recrystallization by inducing a particle-stimulated nucleation mechanism and inhibiting grain growth, which leads to grain refinement and texture weakening. At 250 °C, the ultimate tensile strength of the EK30-2.0Ag alloy (225.9 MPa) increased by 13.8% compared to the Ag-free alloy (198.4 MPa). When the tensile temperature increased from 25 °C to 250 °C, the ultimate tensile strength of the EK30-2.0Ag alloy decreased by 14.3%, from 263.7 MPa to 225.9 MPa. Notably, the addition of Ag slightly reduced the elongation of the alloy at 250 °C; the elongations of the EK30-2.0Ag alloy and the EK30 alloy are 41.5% and 37.0%, respectively. The elongation of the EK30-2.0Ag alloy increased from 22.7% at 25 °C to 52.7% at 275 °C. All alloy tensile fractures exhibited typical plastic fracture characteristics. This study provides an effective way to enhance the high-temperature mechanical properties of magnesium alloys by Ag alloying and a special severe plastic deformation method.
