Preparation And Microstructure Optimization Of TiB/Ti Continuous Gradient Composites

Titanium-based gradient composites are widely used in aerospace and weapon armor due to the design of components.They can meet the requirements of high strength,high hardness,high toughness,high temperature resistance,corrosion resistance and easy processing,but at the interface between layers.The difference between thermal mismatch and acoustic impedance tends to greatly reduce its service life and increase its safety hazards,which has become a major application problem for this material.Eliminating the interlayer interface of titanium-based gradient composites and achieving continuous gradient changes in material composition is an effective way to solve this problem.Based on this,a thin Ti/TiB₂ casting zone was prepared by organic casting.After stacking,the plasma induced by spark plasma sintering?SPS?promoted the rapid diffusion of B atoms and generated rod-shaped TiB in situ.The interlayer interface was eliminated,and a TiB/Ti composite material satisfying the continuous gradient change of the composition was prepared.The Ti/TiB₂ casting belts with certain toughness and strength were prepared by organic casting method.The influence of solid phase content,dispersant,binder and plasticizer content on the rheological properties of the casting slurry was studied.Ti/TiB₂ casting belts with good toughness and good surface condition.The TiB/Ti continuous gradient composite was prepared by SPS one-step sintering.The optimal SPS sintering process was as follows:sintering temperature was 1350°C,sintering pressure was 40MPa,and holding time was 5min,which ensured high-enhancement phase content and dense phase.Titanium grains in the volume content end do not grow abnormally,preventing a significant reduction in material toughness.The phase,microstructure and mechanical properties of 10-80vol.%TiB/Ti composites prepared according to the above process were tested.TiB/Ti composites in different compositions were whisker-like,with TiB volume fraction.The increase of diameter,the diameter-to-diameter ratio gradually decreases,the density of TiB/Ti composites with different compositions exceeds 96.25%,the hardness increases from4.28GPa to 14.05GPa,and the flexural strength and fracture toughness are from1795.4MPa and 15.81MPa·m^1/2 was reduced to 281 MPa and 4.43MPa·m^1/2,and the modulus of elasticity increased from 114.4GPa to 389.0GPa.The phase relationship between TiB and?-Ti is:?100?TiB//?100??-Ti,?011?TiB//?12?2??-Ti,[01?1]TiB//[011]?-Ti.TiB is achieved by stacking with the lowest?100?plane of?-Ti mismatch and growth along the[010]direction.The ANSYS-LSDYNA finite element simulation design of TiB/Ti continuous gradient composites was carried out,and the linear continuous layer thickness?component gradient slope size?in the composite was optimized.The results show that the impact resistance was best when the continuous gradient layer is 1.4mm,and the projectile was reduced from 1000m/s to 459m/s.According to the above design results,TiB/Ti continuous gradient composites were prepared and analyzed by scanning electron microscopy?SEM?,3D-ray microscopy?3D-CT?.The results show that there is no obvious interface in the material.And the enhancement phase exhibits a continuous gradient distribution.