【作者】 张彬；

【导师】 张法明；

【作者基本信息】 东南大学 ， 材料科学与工程， 2021， 硕士

【摘要】 钛基复合材料（TMCs）具有高强度、良好的耐磨性和耐腐蚀性而被广泛应用于航空器的结构件材料。原位生成的Ti Cp和Ti Bw被认为是钛基复合材料的理想增强体材料。石墨烯（GR）具备优异的力学性能,在被应用于钛基复合材料的增强体材料时具有很高的强化效率。本论文以纳米Ti C（约50nm）/纳米Ti B₂（约300nm）粉末和多层GR（<10层）粉末作为增强体材料,大尺寸Ti6Al4V（TC4）球状粉末作为基体材料,制备了原位多元增强的GR-Ti Cp/TC4和GR-Ti Bw/TC4复合材料。通过在TC4表面包裹Ti C或Ti B₂形成隔绝层以期减少GR与TC4的反应。本文中研究了不同增强相含量的复合材料的物相结构、显微组织、力学性能和强韧化机理。主要研究内容及结果如下:（1）研究了TC4经不同烧结温度烧结成型后的致密度,研究了烧结态复合材料样品经不同的热变形处理（锻造镦粗、热轧）后的变形率和组织结构。结果表明900℃烧结5min后TC4的致密度达到98.57%。锻造镦粗的变形率仅能达到43.6%,且组织结构变形不明显。而热轧的变形率高达69.40%,热轧后的组织结构发生明显变形。（2）研究了GR-Ti Cp/TC4复合材料经900℃烧结和1000℃热轧后的组织结构与性能变化。结果表明经900℃烧结后,GR添加量为0.4wt.%、纳米Ti C添加量为0.05wt.%的GR-Ti Cp/TC4呈现准连续的网状结构组织,显微硬度（354.66HV）、抗拉强度（1033MPa）和抗压强度（1856MPa）大幅度提高,较TC4分别提高了19.5%,20.7%和6.8%。烧结态的GR-Ti Cp/TC4经1000℃热轧后等轴组织被拉伸变长。GR添加量为0.3wt.%的GR-Ti Cp/TC4经过热轧后抗拉强度（1110MPa）比烧结态样品（991MPa）提升了12.0%,断裂时的最大应变达到12.9%。（3）研究了GR-Ti Bw/TC4复合材料经900℃烧结和1000℃热轧后的组织结构与性能变化。结果表明经900℃烧结后,GR添加量为0.4wt.%、纳米Ti B₂添加量为0.45wt.%的GR-Ti Bw/TC4呈现封闭的连续网络状分布。GR添加量为0.3wt.%、纳米Ti B₂添加量为0.05wt.%的GR-Ti Bw/TC4的显微硬度（348.93HV）、抗拉强度（1016MPa）和抗压强度（1821MPa）较TC4分别提升了17.7%,27.7%和8.8%,经1000℃热轧和570℃退火后抗拉强度（1128MPa）进一步提升了11.0%,断裂时的最大应变能达到14%,在提高强度的同时能够保持一定的塑性。在GR添加量一样,Ti C和Ti B₂添加量一致时,GR-Ti Bw/TC4复合材料的强韧化效果优于GR-Ti Cp/TC4复合材料。更多还原

【Abstract】 Titanium matrix composites（TMCs）have been widely used in aircraft structural materials due to its high strength,good wear resistance and favourable corrosion resistance.In-situ Ti C particles and in-situ Ti B whisters are considered to be ideal reinforcement materials for titanium matrix composites.Graphene（GR）has excellent mechanical properties and has high strengthening efficiency when it is used as reinforcement of titanium matrix composites.In this paper,in-situ multi-reinforced GR-Ti Cp/TC4 composites and GR-Ti Bw/TC4 composites are prepared with nano-Ti C（～50nm）/nano-Ti B₂（～300 nm）and GR as reinforcement material and large size TC4spherical powders as matrix material.The reaction between GR and TC4 is expected to be alleviated by coating Ti C or Ti B₂ on the surface of TC4 to form a barrier.In this paper,the phase structure,microstructure,mechanical properties and toughening mechanism of composites with different content of reinforcing phase were studied.The main research contents and results are as follows:（1）The density of TC4 after sintering at different temperatures is studied.The deformation ratio and microstructure of composites after different thermal deformation treatments（forging upsetting,hot rolling）are studied.The result shows that the density of TC4 reached 98.57%after sintering at 900℃for 5min.The deformation ratio of forging upsetting can merely reach 43.6%,and the deformed microstructure is not obvious.However,the deformation ratio of hot rolling can reach 69.40%,and the microstructure is obviously deformed after hot rolling.（2）The microstructure and properties of GR-Ti Cp/TC4 composites are investigated after sintering at 900℃and hot rolling at 1000℃.The result shows that after sintering at 900℃,the GR-Ti Cp/TC4 with 0.4wt.%GR and 0.05wt.%nano-Ti C shows a quasi-continuous network structure.The microhardness（354.66HV）,tensile strength（1033MPa）and compressive strength（1856MPa）of it are greatly increased by19.5%,20.7%and 6.8%compared with TC4,respectively.After hot rolling at 1000℃,the equiaxial microstructure of sintered GR-Ti Cp/TC4 becomes longer.The tensile strength of hot rolled GR-Ti Cp/TC4 with 0.3wt.%GR（1110MPa）is 12.0%higher than that of sintered samples（991MPa）and he fracture strain of it reaches 12.9%.（3）The microstructure and properties of GR-Ti Bw/TC4 composites are investigated after sintering at 900℃and hot rolling at 1000℃。The result shows that after sintering at 900℃,the GR-Ti Bw/TC4 with 0.4wt.%GR and 0.45wt.%nano-Ti B₂presents a closed continuous network distribution.Compared with TC4,the micro-hardness（348.93MPa）,ultimate tensile strength（1016MPa）and ultimate compsite strength（1821MPa）of GR-Ti Bw/TC4 with 0.3wt.%GR and 0.05wt.%nano-Ti B₂ is increased by 17.7%,27.7%and 8.8%,respectively.The tensile strength of GR-Ti Bw/TC4 with 0.3wt.%GR（1821MPa）is further increased by 11.0%after hot rolling at 1000℃and annealing at 570℃.The fracture strain of it reaches 14%.The strength of the composite material is improved while the plasticity is matained.When the addition of GR is unchanged and simultaneously the addution of Ti C and Ti B₂ are the same,the strength and toughening effect of GR-Ti Bw/TC4 composites is better than that of GR-Ti Cp/TC4 composites.更多还原