Study On Microstructure And Properties Of (TiC+Al₂O₃)/Ti6A14V Composites

In situ TiC particles and Al2O3 particles reinforced Ti6Al4V matrix composites has been successfully fabricated using melting-casting process. The phase constituent and evolution of TiC in the composites and the effect of Al2O3 on morphology of TiC were investigated. The compression properties and wear performance were also tested. These experiments were carried out on X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscope(TEM), wear testing machine, universal material testing machine.It is resulted that there are four morphologies of reinforced phase in the (TiC+Al2O3)/Ti6Al4V composites: granules, bar, featheriness and dendrite morphology along with C content growing from 0.6%,0.8% to 1%. With the increasing of Al2O3 volume fraction, the exiguous dendrite TiC were replaced with short-bar shaped particles, The average grain size of TiC dendrite was decreased gradually and has been fairly well-distributed. Sur-Al2O3 has an effect on mass and heat transfer in the front of TiC growth interface, thus the full growth of TiC has been prevented, then the primary TiC becomes finer.The hardness and the compressive properties of (TiC+Al2O3)/Ti6Al4V composites increases, and the plastic strain reduces gradually with an increase of TiC and Al2O3 particulate content. The compressive properties of the composites with 1%C,2% Al2O3 was highest, about 2070MPa. The fracture of the composites was diverted from the manner of intergranular brittle fracture with dimple gliding fracture to the manner of intergranular brittle fracture with the increase of the reinforcements TiC and Al2O3. The reinforcement can enhance the deformational resistance of the substrate alloys through locking mechanism and hindering the movement of the dislocation in the sliding deformation.The wear resistance of the composites has gradually improved with the increase of the reinforcements TiC and Al2O3. It is found that the wear surface of the composites changes from the continual profound grinding groove to the small amount of slight chafing morphology, and the abrasion mechanism varies from serious abrasive grain abrasion to slight adhesive wear. The results indicate that the wear resistance of the composites in the simulated body fluid is better than in dry-slidy could reduce liding wear because of some abrasive debris being carried off by the lubricant performance and the floating fluid of the simulated body fluid. The reinforcements of high hardness and abrasion resistant TiC, Al2O3 could reduce the abrasion and improve the abrasion resistance of the composites by preventing the falling flinty debris from being pressed into the surface of composites to cause the serious attrition as grinding groove.