(湖南大学 材料科学与工程学院，长沙 410082)
摘 要: 研究AZ31镁合金轧制板材在低温(室温至423 K)拉伸条件下的力学性能，并通过高温金相显微镜的拉伸附件观察动态微观组织的变化过程。结果发现：镁合金的塑性随温度的升高和应变速率及负载的降低而增 加，表现出一定的应变速率敏感性。常温下的主要变形机制为{1110}压缩孪生，其形核和长大速度很快，但同时也存在少量的基面滑移，不同类型的孪晶在晶粒中彼此相交；而随着温度的升高，a+c非基面滑移的临界剪切应力迅速下降，大量非基面滑移系被激发，板材塑性性能明显改善；当应变速率较高时(423 K，应变速率10−2 /s)，断裂方式为有一定塑性特征的解理形貌；随着应变速率的降低(423 K，应变速率10−3 /s)，断裂方式逐渐变为塑性断裂。
关键字: 镁合金；压缩孪晶；基面滑移；变形行为；断裂机制
（School of Materials Science and Engineering, Hunan University, Changsha 410082, China）
Abstract:The mechanical behavior and dynamic microstructural evolution of hot-rolled AZ31 Mg alloy were studied by tensile attachment of high-temperature microscopy (HTM) at different temperatures from room temperature (RT) to 423 K. The results show that the ductility of Mg alloy material increases with the increase of deformation temperature and the decreases of load and strain rate and has certain strain rate sensitivity. The main deformation evolution is {1110} contraction twinning at RT which has high nucleation rate and growth velocity and little basal slips. Different types of twins can intersect with each other and results in severe shear in the existing twin. With the increase of temperature, the critical resolved shear stress (CRSS) of a+c non-basal slip is surpassed easily, a great many non-basal slip systems are activated and the plastic property of Mg alloy is improved obviously. At 423 K, when the strain rate is 10−2 /s, the alloy exhibits ductile fracture with dimples. With the decrease of strain rate (10−3 /s), the fracture transfer plastic deformation step by step.
Key words: magnesium alloys; contraction twin; basal slip; deformation behavior; fracture mechanism
