Microstructure and mechanical properties of high performance Mg-Gd based alloys

The Mg-12Gd-4Y-2Nd-0.3Zn-0.6Zr (wt.%) alloy was prepared by casting technology, and the structure, age hardening behavior and mechanical properties of the alloy have been investigated. The results demonstrated that the alloy was composed of alpha-Mg matrix, a lot of dispersed Mg24RE5 (RE = Gd/Y/Nd) and Mg5RE precipitates in the as-cast and the T6 state alloys. The alloy exhibited remarkable age hardening response and excellent mechanical properties from room temperature (RT) to 300 degrees C by optimum solid solution and aging conditions. The ultimate tensile strength. yield strength and elongation of the alloy at peak hardness were 310 MPa, 280 MPa and 2.8% at RT, and 293 MPa, 261 MPa and 5.8% at 300 degrees C, respectively. The high mechanical properties were mainly attributed to the fine microstructure, fine metastable precipitate and the dispersed precipitates in the matrix. (C) 2008 Elsevier Ltd. All rights reserved.