Effects of extrusion on the microstructure and mechanical properties of Mg-Zn-Gd alloy reinforced with quasicrystalline particles

The microstructure and mechanical properties of Mg95.9Zn3.5Gd0.6 alloy reinforced with icosahedral quasi-crystalline particles (I-phase) were investigated after extrusion at 573 K and 673 K. The effects of extrusion temperature and heat treatment on the microstructure and mechanical properties of the alloy were analyzed and the strengthening effect of I-phase was discussed. The results show that the I-phase is significantly refined upon extrusion. At room temperature, the alloy extruded at 573 K exhibits better tensile mechanical properties as compared to the alloy extruded at 673 K. At 473 K, the as-extruded alloy exhibits high elongation of about 94% due to the high cohesion of the I-phase with the matrix. As compared to the alloy extruded at 573 K, the alloy extruded at 673 K exhibits higher precipitate strengthening effect due to a higher density of I-phase precipitates, which results in not only a high ultimate tensile strength of 117 MPa, but also a high elongation of 82.5% at 473 K.