铸态和挤压变形态Mg-Zn-Al-Re镁合金的室温和高温力学性能

Mechanical Properties of as-Cast and as-Extruded Mg-Zn-Al-Re Magnesium Alloys at Room Temperature and Elevated Temperatures

摘要:

采用透射电子显微镜、扫描电子显微镜及能谱分析、拉伸力学性能测试等手段比较分析了铸态和挤压变形态Mg-7Zn-3Al-0~0.7Re (质量分数, %) 镁合金的室温和高温力学性能，探讨了稀土和变形加工对合金强度和塑性的影响规律。结果表明，适量稀土Er可以显著提高铸态Mg-Zn-Al合金的高温塑性，而稀土含量对合金室温力学性能和高温屈服强度影响不明显；挤压变形过程中动态弥散析出纳米级的球形析出相，显著提高Mg-Zn-Al-Er合金的高温力学性能，其200 ℃下的屈服强度和延伸率分别较铸态提高了105%和120%，断口显示其断裂方式呈明显的韧性断裂特征

Abstract:

Mechanical properties of as-cast and as-extruded Mg-7Zn-3Al-0~0.7Re(wt%) magnesium alloys both at room temperature and elevated temperatures were compared by means of TEM, SEM, EDS and tensile mechanical property testing, and the effects of rare-earth addition and deformation on the strength and plasticity of the alloys were analyzed. The results show that the proper addition of Er could dramatically increase the elevated temperature plasticity of as-cast Mg-Zn-Al alloy, while it would not change much the room temperature mechanical properties and the elevated temperature yield strength. It is also revealed that spherical nano-precipitates occurred during the extrusion, which increased the elevated temperature mechanical properties of the as-extruded Mg-Zn-Al-Er alloy remarkably. Compared to those of the as-cast alloy, the yield strength and elongation of the as-extruded alloy at 200 °C were increased by 105% and 120%, respectively. Furthermore, fractographs present an obvious tough fracture feature