Study On Fabrication And Property Of TiB₂/2024Composites By In-situ Reaction Method

The MMCs has gotten great attention by its high strengthen、high toughness、high hardness、great wear resistance and high temperature property. The aluminummatrix composites except for other advantages of metal matrix composites, also haslight weight, high elastic modulus and other advantages, including the study ofpreparation and performance of continuous updating of aluminum matrix composites,become the focus of people.In this paper, using the in situ reaction method of Al-Ti-B system, with TiO2andKBF4as reaction solvent, successfully prepared reinforcement particles TiB2. At acertain temperature, the evenly mixed powder was added to the melting alloy liquid,and continuously stirring exerted even when the reaction completed, so the generatedparticles can be evenly distributed, after the reaction stop, standing for a period oftime, then slagging off and pouring. After extracting of the material, result of XRDphase analysis show that in addition to the enhanced particle TiB2, there are certainTiB generated. So the reinforcement particles can be identified as TiBx. In addition,some Al2O3and Al3Ti also be detected.Firstly, the cylindrical ingot prepared must be carried on homogenizationtreatment, here is homogenizing annealing. Then the specimens were processed forhot extrusion to get small size of the bars. So that the density of the material has beengreatly improved, at the same time, the casting defects are reduced obviously, thusprepared composite material with better mechanical properties. From themicrostructure figures, the distribution of the longitudinal section along the material isstreamlined, the same as the strip particles.The as-cast samples and extrusion samples of2024and TiB2/2024were carriedon T6treatment, heat treatment using cross test to find out the optimal parameters value, so as to the microstructure and properties of materials are improvedsimultaneously.The mechanical properties (tensile strength and wear resistance) of materialsboth before and after treatment were studied. The results show that the wear propertyof MMCs are higher than2024, meanwhile their strength of extension and wearresistant are rise simultaneously, with a slight loss of toughness. After hot extrusion,the toughness and strength of2024and TiB2/2024are improved; especially theextruded TiB2/2024composites after T6treatment can maintain a high level. At thesame time, its wear resistance and hardness showed superior in the comparedexperiment. With no loss of ductility, particle phases in the extruded compositesimprove the strength of the materials.