Deformation behavior of Mg-Zn-Gd-based alloys reinforced with quasicrystal and Laves phases at elevated temperatures

Mg-Zn-Gd and Mg-Zn-Gd-Cu alloys, reinforced with quasicrystal (I-phase) and Laves phases, have been produced by extrusion process. The deformation behavior of these two alloys at room temperature and at elevated temperatures was investigated, respectively. The Mg-Zn-Gd alloy has high UTS of 305 MPa and elongation of 14.6% due to the strengthening effect of I-phase, while Mg-Zn-Gd-Cu alloy with Laves phases has higher yield stress of 217 MPa due to more strengthening particles and lower elongation of 11.9% resulting from the low content of I-phase and low symmetry of Laves phase due to which it cleaves easily (while the I-phase has a very high symmetry and therefore isotropic in nature). At high temperatures, Mg-Zn-Gd alloy shows large strain due to the excellent plastic compatibility coming from low interfacial energy of I-phase/matrix; Mg-Zn-Gd-Cu alloy has higher level of flow stress, strain exponent and more stable microstructure than Mg-Zn-Gd alloy due to better heat-resistance supplied by collaboration of Laves phases and quasicrystal phase, which can provide more effective pinning effect and suppress grain growth during deformation. (c) 2006 Elsevier B.V. All rights reserved.