2. Materials and experimental proce

2. Materials and experimental proceduresThe composition of the Mg-Gd-Y-Zn-Zr alloy used in the present study was Mg-8.90Gd-5.11Y-3.10Zn-0.47Zr. It was prepared by using semi-continuous casting. The as-cast ingot was homogenized at 510℃ for 20 h and then was extruded into the rod with a diameter of 45mm by an extrusion ratio of 15:1 at 420℃. The cylindrical samples with a diameter of 8mm and a length of 12mm were machined from the extruded rod, the compression direction was parallel to the extrusion direction, as shown in Fig.1. Uniaxial compression tests were conducted at constant true strain rates in the range of 0.001-1s-1 and temperatures range of 300-500℃ on the Gleeble-3500 thermo-mechanical simulator, the cylindrical surface of samples were polished before compression testing. The samples were first heated up to the deformation temperature at a rate of 3℃/s and then held isothermally for 300s prior to isothermal compression. In order to reduce the deformed friction, a graphite lubricant was used between the sample and the crosshead. The samples were deformed up to a true strain of 1.2. After deformation, all samples were quenched in water immediately to maintain deformed microstructures.The specimens for microstructure analysis were sectioned in the center parallel to the compression axis. The etching solution was the solution of 4vol. % HNO3 with ethanol. Sample for tensile testing was machined from the component using a MTS material testing machine. Crosshead speed was 2mm/min, and the gauge length was 50mm.