摘要
通过测定蠕变曲线,对蠕变不同阶段组织形貌的SEM、TEM观察,及结合蠕变期间高温显微镜的原位动态观察,研究了AZ31镁合金蠕变期间的组织演化和断裂特征.结果表明:该合金在蠕变期间具有较高的应变速率,应变产生的高密度位错,在热激活作用下可发生合金的动态再结晶;晶内多取向滑移是稳态蠕变后期的形变机制;在蠕变第三阶段,裂纹在晶界处产生,并沿晶界韧性撕裂扩展是该合金的蠕变断裂机制;而远、近断口处均发生晶内滑移和沿晶界韧性撕裂扩展是致使合金具有较高总应变量的直接原因.
By means of measuring creep curves and observing of SEM, TEM, an investigation has been made into the features and the microstructure evolution during high temperature creep for AZ31 MgAlloy. The results show that the alloy possesses a higher strain rate during creep. In the role of the heat activation, the denser dislocations produced during deformation may result in the dynamic recrystallization. After recrystallization, the multiorientation slips within the grain are supposed to be the main deformed mechanism in the later stage of the steady state creep. The cracks appear in the grain boundary when creep enters the tertiary stage. As creep goes on, the fact that the cracks are viscously expanded along the grain boundary is supposed to be the fracture mechanism of creep for the alloy. Further, the slips within the grain and the cracks expanded viscous along the grain boundary appear in the regions, which is far and near the fracture will result in a higher strain value after the alloy creep to fracture.
出处
《沈阳工业大学学报》
EI
CAS
2003年第1期23-27,共5页
Journal of Shenyang University of Technology
