| In situ Ti B2 particle reinforced Al matrix composite has been widely used in aerial fields due to its high strength, high modulus and high rigidity. However, with the increasing requirements on the combination properties of materials, we are in a urgent need of composites with higher properties. As concerned, the microstructure of the material is the major factor to determine the mechanical properties of the material. Hence, in order to increase the combination properties of Ti B2 particle reinforced Al matrix composite, we firstly focused on its microstructure and deformation mechanism. Accordingly, this paper analyzed the microstructure of the composites and tested the mechanical properties of four 5%Ti B2/Al composites after cold-rolled to 60%, 75%, 90% and 95%, respectively. In this way, we can extract the deformation mechanism and microstructure of Ti B2/Al composite.SEM, EBSD and Neutron Diffraction characterization methods were used to analyze the microstructure of the four Ti B2/Al composites with different reductions. The results show that some Ti B2 particles aggregate around the grain boundaries while others distribute homogeneously within grains. The particles gathered around the grain boundaries will induce the formation of high angle grain boundaries, while the particles distributed in grains would inhibit the movement of dislocations and grain boundaries which lead to the harder generation of grain boundaries compared to Aluminum alloys. Besides, the strain is concentrated around the aggregated Ti B2 particle zone, which will encourage the recrystallization during deformation process. Nevertheless, at the same time, the homogeneously distributed Ti B2 particles will hinder the movement of grain boundaries which can inhibit the growing-up of recrystallized grains. We also observed that the Ti B2/Al composite is a kind of extremely uneven material, in which more than 90% of the grains have a diameter smaller than 2μm and take up less than 22% of the area fraction, while less than 10% of the grains are larger than 2μm but account for more than 78% of the area fraction. In addition, the texture volume and texture sharpness of Ti B2/Al composite are both smaller than those of Al alloys. A novel investigation is also noted that the homogeneously distributed Ti B2 particles will rotated with the surrounding Al matrix during the cold-rolling deformation.Room temperature tensile test was utilized to measure the mechanical properties of four Ti B2/Al composites with different reductions. The results indicates that the composite with higher deformation reductions has higher strength and lower plasticity. The strengthen mechanism of these Ti B2/Al composites were analyzed including small grain strengthen, hard working strengthen and Orowan strengthen. The results of microstructure and deformation mechanism of Ti B2/Al composite provide a fundamental theory for further improving the properties of Ti B2/Al composite. |
