In order to improve the ductility of commercial WE43 alloy and reduce its cost, a Mg-3Y-2Gd-1Nd-0.4Zr alloy with a low amount of rare earths was developed and prepared by sand casting with a differential pressure casting system. Its microstructure, mechanical properties and fracture behaviors in the as-cast, solution-treated and as-aged states were evaluated. It is found that the aged alloy exhibited excellent comprehensive mechanical properties owing to the fine dense plate-shaped β' precipitates formed on prismatic habits during aging at 200 °C for 192 hrs after solution-treated at 500 °C for 24 hrs. Its ultimate tensile strength, yield strength, and elongation at ambient temperature reach to 319 ± 10 MPa, 202 ± 2 MPa and 8.7 ± 0.3% as well as 230 ± 4 MPa, 155 ± 1 MPa and 16.0 ± 0.5% at 250 °C. The fracture mode of as-aged alloy was transferred from cleavage at room temperature to quasi-cleavage and ductile fracture at the test temperature 300 °C. The properties of large-scale components fabricated using the developed Mg-3Y-2Gd-1Nd-0.4Zr alloy are better than those of commercial WE43 alloy, suggesting that the new developed alloy is a good candidate to fabricate the large complex thin-walled components.

为了提高商用WE43合金的延展性并降低其成本，开发并采用差压铸造系统砂型铸造制备了低稀土含量的Mg-3Y-2Gd-1Nd-0.4Zr合金。评估了其在铸态、固溶处理和时效状态下的显微组织、力学性能和断裂行为。研究发现，时效合金在500℃固溶处理24小时后，在200℃时效192小时时，在棱柱状习性上形成细密的板状β'析出物，从而表现出优异的综合力学性能。其常温极限拉伸强度、屈服强度和伸长率分别达到319±10MPa、202±2MPa和8.7±0.3%，250℃时达到230±4MPa、155±1MPa和16.0±0.5% 。时效合金的断裂模式由室温解理转变为300 ℃试验温度下的准解理和韧性断裂。使用所开发的Mg-3Y-2Gd-1Nd-0.4Zr合金制造的大型构件的性能优于商业WE43合金，这表明新开发的合金是制造大型复杂薄壁构件的良好候选者。