力学性能的影响
(1.中南大学 材料科学与工程学院，长沙 410083；
2.中国兵器科学研究院 宁波分院，宁波 315103)
摘 要: 利用光学显微镜、扫描电子显微镜、X射线衍射仪等研究二次挤压对Mg-12Gd-3Y-0.6Zr合金显微组织及力学性能的影响。研究表明：该合金经二次挤压后，晶粒尺寸细化至6 μm，提高细晶强化效果；粗大Mg5Gd1−xYx相增多，降低固溶强化效果；{0002}基面织构的减弱降低织构强化效果；在三者的综合作用下，合金经二次挤压后，强度有所降低，但伸长率却大幅度提高，达到20.5%，较一次挤压态合金的伸长率提高107.1%；一次挤压态合金的断裂方式是以解理断裂为主的混合断裂，二次挤压态合金的断裂方式为韧性断裂。
关键字: Mg-12Gd-3Y-0.6Zr合金；显微组织；二次挤压；力学性能；织构
mechanical properties of Mg-12Gd-3Y-0.6Zr alloy
（1. School of Materials Science and Engineering, Central South University, Changsha 410083,China;
2. Ningbo Branch, Ordnance Science Institute of China, Ningbo 315103, China）
Abstract:The effect of double-extrusion on the microstructure and mechanical properties of Mg-12Gd-3Y-0.6Zr alloy was studied by optic microscopy (OM), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results show that, after double-extrusion, the grain size of this alloy is refined to 6 μm, which improves the strengthening effect of the fine grain. The coarse Mg5 Gd1−xYx phase increases, resulting in the decreases of solution strengthening effect. The weakening of {0002} basal plane texture decreases the strengthening effect of the texture. Under the comprehensive effect of the three factors, the strength of this alloy decreases slightly after double-extrusion, whereas the elongation increases remarkably to 20.5%, which is increased by 107.1% compared with that of the as-once-extruded alloy. The fracture mechanism of the as-once-extruded alloy is compound fracture cleavage fracture, and that of the as-double-extruded alloy is toughness and fracture.
Key words: Mg-12Gd-3Y-0.6Zr alloy; microstructure; double-extrusion; mechanical properties; texture
