Microstructure And Mechanical Properties Of ?TiBw+?Ti,Zr?₅Si₃?/TA15 Composites

TA15 particles with an average particle size of 150?m,TiB₂ powder?3?m?and high-purity Si powder?3?m?were used as raw materials.Low-energy ball milling and hot-press sintering were used to prepare?Ti Bw+?Ti,Zr?₅Si₃?/TA15 composite material with different reinforcing phase contents based on in-situ autogenous reaction and powder metallurgy techniques.By adjusting the reinforcing material content,solid solution aging temperature and rolling deformation of the composite material,the room temperature tensile,high temperature tensile and high temperature creep properties of the test material were tested,and the fracture and toughening mechanism of the composite material was analyzed.The resulting composites were characterized by optical microscopy?OM?,scanning electron microscopy?SEM?and transmission electron microscopy?TEM?.The microstructure analysis shows that the silicides produced by in-situ autogeneous reaction of the composites are mainly?Ti,Zr?₅Si₃,which are nearly short rods,mainly distributed around the?phase and at the?/?phase interface,and the silicide play a certain role in the refinement of?-phase.After solution treatment at 1100°C/40min/WQ+500-700°C/5h/AC,the microstructure transforms into a stable,fine-needle??+??widman tissue,and the solid solution silicide re-distributes uniformly.The size is smaller.After hot rolling,the grain refinement occurs and the grain is elongated obviously.The microstructure is mainly composed of lamellar?-phase and fine needle-like?-phase bundles.The whisker breaks severely and the connectivity of the reinforcement decreases.When the rolling deformation increased to 80%,a large number of fine equiaxed?grains were observed.The room temperature and high temperature tensile test results show that the composite has a good room temperature and high temperature enhancement effect.The room temperature tensile strength and elongation?1107.4MPa/5.7%?of TMCs-0.5Si composites were increased by 30.2%and 19.7%respectively,compared with matrix TA15?864MPa/4.8%?.Tensile strength at 600°C?661.9MPa?was increased by 50%,compared with the matrix TA15?439.7 MPa?.Solid solution aging treatment can further increase the strength level of composites,which is mainly due to the dispersion strengthening effect of the secondary needle-like?phase.The hot rolling treatment made the strength and elongation of the composite significantly improved.When the rolling deformation was 60%,the tensile strength of the composite at room temperature reached1238.2 Mpa,and the elongation reached more than 10%.Compared with before rolling,the tensile strength and elongation?508.4MPa,28.6%?of the composite at 700°C increased by 13.1%and 46.7%respectively.This shows that the hot rolling treatment can improve the performance of the composite material to some extent.The high temperature creep tests show that the addition of silicon can significantly improve the high temperature durability of the composites.Under the conditions of 650°C and 200 MPa,the creep rupture time of TMCs-1Si is nearly 4 times higher than that of the matrix.This is mainly due to the hindrance of the disperse silicide to dislocations.After solid solution aging treatment,the appearance of fine-needle??+??widman tissue,and the silicide re-precipitates and distributes evenly.As a result,the high-temperature durability performance is improved to a certain extent compared with the solid solution state,but it is lower than that of the sintered state.Hot rolling treatment can further improve the high-temperature durability properties of the composites.When the deformation amount is 40%and 60%,the high-temperature permanent fracture time of the as-rolled composites increases 26.3%and 18.4%,respectively,compared with the as-sintered state.This is mainly related to the rotation of TiB short fibers in the direction of creep stress and to some extent grain refinement.Based on the results of the microstructure characterization and the mechanical properties,it is believed that the TiB whiskers can effectively bear the load and transfer strain,and the composites have good room temperature and high temperature enhancement.Through the hindrance of the disperse silicide to dislocations,the material's high temperature durability significantly increased.Through solid solution aging treatment,the material's strength is effectively improved.Through hot rolling treatment,the material's strength,plasticity,and high temperature durability properties are significantly improved.