【作者】 刘悦；

【导师】 黄陆军；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2018， 硕士

【摘要】 本文以平均粒径150μm的TA15颗粒、3μm的TiB₂粉末以及3μm的高纯Si粉为原料,采用低能球磨与热压烧结的方法,基于原位自生反应与粉末冶金技术制备不同增强相含量的（TiBw+（Ti,Zr）₅Si₃）/TA15复合材料。通过调整复合材料的增强体含量、固溶时效温度以及轧制变形量,测试材料的室温拉伸、高温拉伸以及高温蠕变性能,分析其断裂及强化机制。利用光学显微镜（OM）、扫描电子显微镜（SEM）以及透射电子显微镜（TEM）对复合材料进行组织表征和断裂分析。微观组织分析表明,复合材料通过原位自生反应生成的硅化物的主要是（Ti,Zr）₅Si₃,为近短棒状,主要分布在β相周围及α/β相界面处,并对β相起到了一定的细化作用。经1100℃/40min/WQ+500-700℃/5h/AC固溶时效处理后,组织转变为稳定的细针状（α+β）魏氏体组织,固溶硅化物重新均匀弥散的析出,尺寸更加细小。热轧制处理后,晶粒细化且被明显拉长,组织主要是由层片状α相与细针状β相集束组成,晶须发生严重折断现象,增强相连通度降低。轧制变形量增加到80%,可见大量细小的等轴状α晶粒。室温及高温拉伸测试结果表明,复合材料有着良好的室温及高温增强效果,TMCs-0.5Si复合材料的室温抗拉强度和延伸率（1107.4MPa/5.7%）较基体（864MPa/4.8%）分别提高了30.2%和19.7%;在600℃下的抗拉强度（661.9MPa）较基体TA15（439.7MPa）提高了50%。固溶时效处理可以进一步提高复合材料的强度水平,这主要是由于次生针状α相的弥散强化作用。热轧制处理使得复合材料的强度和延伸率均得到显著提高,轧制变形量为60%时,材料的室温抗拉强度达到1238.2Mpa,延伸率达到10%以上,700℃下的抗拉强度和延伸率（508.4MPa/28.6%）较未轧制前分别提高了13.1%和46.7%,这说明热轧制处理可以在一定程度上提高复合材料的性能。高温蠕变测试结果表明,硅元素的加入可以显著提高材料的高温持久性能,在650℃、200MPa的实验温度及应力参数条件下,TMCs-1Si的蠕变断裂时间较基体提高了近4倍,这主要是由于弥散分布的硅化物对位错的阻碍作用。固溶时效处理后,细针状（α+β）魏氏体组织的出现以及固溶的硅化物重新均匀弥散的析出,使得高温蠕变性能较固溶态一定程度上提升,但较烧结态发生下降。热轧制处理可以进一步提高复合材料的高温持久性能,其中变形量为40%和60%的轧制态材料的持久断裂时间较烧结态分别提高了26.3%和18.4%,这主要与TiB短纤维向蠕变应力方向转动以及一定程度上的晶粒细化有关。结合组织表征结果以及力学性能的测试结果,认为该种复合材料通过TiB晶须可以有效承担载荷、传递应变,起到了良好的室温及高温增强效果;通过硅化物对位错的阻碍作用,显著提高了材料的高温持久性能。通过固溶时效处理,有效提高了材料的强度。通过热轧制处理,显著提高了材料的强韧性水平以及高温持久性能。更多还原

【Abstract】 TA15 particles with an average particle size of 150μm,TiB₂ powder（3μm）and high-purity Si powder（3μm）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 theβphase and at theα/βphase interface,and the silicide play a certain role in the refinement ofβ-phase.After solution treatment at 1100°C/40min/WQ+500-700°C/5h/AC,the microstructure transforms into a stable,fine-needle（α+β）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 lamellarα-phase and fine needle-likeβ-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 equiaxedαgrains 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-likeαphase.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（α+β）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.更多还原