Mg2B2O5晶须增强镁基复合材料的组织与界面结构研究

采用光学显微镜、透射电子显微镜和X射线衍射仪研究Mg2B2O5晶须增强镁基复合材料的铸态组织及Mg2B2O5/AZ91D界面反应产物。结果表明:Mg2B2O5晶须具有孪晶结构,其孪生面和晶体生长方向分别为(202)和010];部分Mg2B2O5晶须中存在MgB4O7颗粒相;在基体晶界与Mg2B2O5晶须之间存在等轴状Mg2Si相;Mg2B2O5/AZ91D界面处存在厚度不均匀的MgO和MgB2相界面层。尽管Mg2B2O5、MgO和MgB2之间没有确定的晶体学位相关系,但在特定Mg2B2O5晶须表面观察到(202)Mg2B2O5//(002)MgO,010]Mg2B2O5//110]MgO和(002)MgO//(0001)MgB2,110]MgO//2110]MgB2取向关系。最后,讨论Mg2B2O5晶须对复合材料组织结构和性能的影响。

Microstructure and Interface Characterization of Mg2B2O5 Whisker Reinforced Magnesium Matrix Composites

The microstructure and interface characteristics of Mg2B2O5 whisker-reinforced magnesium matrix composites were investigated using optical microscopy, transmission electron microscopy and X-ray diffraction. It is found that the Mg2B2O5 whiskers have a twinned structure with the (202) as the twin plane and 010] as the growth direction of crystals. The MgB4O7 particles exist in some Mg2B2O5 whiskers. Equiaxial Mg2Si particles exist between the grain boundary of the matrix and the Mg2B2O5 whiskers. The MgO and MgB2 phase interface layers with different thickness are formed at the matrix-whisker interface during the vacuum-gas pressure infiltration process, which result from the interfacial reaction between Mg2B2O5 whisker and Mg matrix. The crystallographic orientation relationships between the Mg2B2O5 whisker and the interfacial reaction products are found to be 010]Mg2B2O5//110]MgO and 110]MgO//]MgB2, and (202)Mg2B2O5//(002)MgO and (002)MgO//(0001)MgB2, respectively. Finally, the factors that influence the microstructure of the Mg2B2O5 whiskers and the presence of the Mg2Si, MgO and MgB2 phases nearby the Mg2B2O5 whiskers were discussed.