TiB+La2O3/Ti基复合材料拉伸断裂的原位表征及其机理研究

In-situ Characterization and Mechanism of Tensile Fracture of（TiB+La2O3）/Ti Matrix Composites

以不同体积分数的Ti B+La2O3原位增强钛基复合材料为研究对象,在室温下对该材料进行SEM原位拉伸实验,通过对裂纹尖端的组织变化以及裂纹扩展路径的原位观察,分别研究了增强体对材料拉伸强度和拉伸断裂行为的影响。结果表明:增加增强体的体积分数可以提高增强体的承载作用并细化基体晶粒,从而提高颗粒增强Ti基复合材料的强度。材料的断裂行为表现为增强体断裂后微裂纹的萌生、扩展及其和滑移带的汇合。高含量的增强体可增加微裂纹的数量,使得其在萌生、扩展后更易与邻近微裂纹或滑移带相贯通,加快宏观裂纹的形成,从而导致了材料塑性的下降。

The in-situ SEM tensile test of Ti B+La2O3in-situ reinforced titanium matrix composites with different volume fraction was carried out at room temperature.The effects of reinforcements on the tensile strength and tensile fracture behavior of the materials were investigated by in-situ observation of the microstructure changes at the crack tip and the crack propagation path.The result shows that,increasing the volume fraction of the reinforcements can increase the bearing capacity of the reinforcements and refine the matrix grains.Thus,the strength of Ti matrix composites reinforced by particles is improved.The fracture behavior of the material is the initiation,propagation and confluence of the microcrack and slip band after the fracture of the reinforcements.High content reinforcements can increase the number of microcracks and it is easier to connect with adjacent microcracks or slip bands after initiation and propagation,and the formation of macroscopic cracks is accelerated.Therefore,the ductility of the composites decreases.