(东莞理工学院 机械工程学院，东莞 523808)
摘 要: 在温度为473~573 K、外加应力为30~100 MPa下，对硅酸铝短纤维增强AZ91D镁基(Al2O3-SiO2(sf)/AZ91D)复合材料及AZ91D镁合金进行拉伸蠕变实验。通过SEM和TEM检测方法对其蠕变微观组织变化和变形规律进行研究。结果表明，当两种材料的真应力指数n=3时，蠕变速率受位错的黏滞性滑移控制；复合材料的门槛应力增大、短纤维有效的承载和传载作用导致复合材料的蠕变抗力显著增大。短纤维表面上的MgO保护层增大了短纤维的承载和传载作用；短纤维的存在阻碍了复合材料的蠕变变形，降低了蠕变变形速率，控制着整个蠕变变形过程。
关键字: 镁基复合材料；蠕变；载荷传递；微观组织
（School of Mechanical Engineering, Dongguan University of Technology, Dongguan 523808, China）
Abstract:The tensile creep tests were conducted on Al2O3-SiO2(sf)/AZ91D composite and an unreinforced AZ91D matrix alloys in the temperature range of 473-573 K and stress range of 30-100 MPa. By scanning electron microscopy and transmission electron microscopy, the microstructural effects on the creep behavior of the two materials were discussed. The results show at a true stress exponent of n=3 for the two materials, and creep rate is affected by the viscosity slip control of the dislocation. The creep resistance of the reinforced material is shown to be considerably improved compared with that of the matrix alloy. The creep strengthening arises mainly from the increase of threshold stress of the composite and the effective load transfer between plastic flow in the matrix and the fibers. The MgO protective layer on the surface of short fibers can increase carrying and transferring of loads of the short fibers. The presence of short fibers can hinder the creep deformation of the composite, reduce the creep deformation rate, and control the whole creep deformation process.
Key words: magnesium matrix composite; creep; load transfer; microstructure
