【作者】 李响；

【导师】 孟祥龙；

【作者基本信息】 哈尔滨工业大学 ， 材料工程（专业学位）， 2020， 硕士

【摘要】 铜基复合材料因克服铜及铜合金强度低、耐热性差缺点而受到广泛关注。在铜基复合材料中,通常采用向基体中引入各种不同类型的增强相,以更得高优异的综合性能。本课题选用室温下为B2母相的Ti Ni颗粒作为增强相,探究其对铜基复合材料的影响规律。本论文通过实验研究与有限元模拟相结合的方式,对Ti Ni/Cu复合材料进行表征。采用真空热压烧结法制备得到铜基复合材料,利用X射线衍射(XRD)、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和电子万能测试机等分析测试手段对增强体原料和复合材料进行性能测试,之后采用ABAQUS/CAE软件构建铜基复合材料的有限元模型,分析Ti Ni增强铜基复合材料拉伸过程中材料内部的应力状态,以此为Ti Ni/Cu复合材料的构建提供借鉴和知道。实验研究方面,首先探究了球磨过程中球磨转速及球磨时间对混合粉末的影响,并确定最佳的球磨工艺参数为球磨转速200 rpm,球磨时间3h。之后,选用不同粒径尺寸的Ti Ni增强相制备铜基复合材料,探究其对复合材料组织结构、相变行为和力学性能的影响。研究结果表明:经真空热压烧结制备得到的复合材料,Ti Ni颗粒增强相与Cu会发生反应生成反应层,反应层Cu:Ti:Ni原子比约为1:1:1;当颗粒尺寸为15-53μm时,反应层厚度约为10μm;颗粒尺寸为53-150μm时,反应层厚度约为6μm。此外,材料在升降温过程中发生B2和B19’之间一步相变,当选用较大尺寸Ti Ni颗粒增强时,复合材料的相变峰更尖锐,相变温度低于Ti Ni预合金化粉末的相变温度;应力-应变曲线表明Ti Ni颗粒尺寸为15-53μm比53-150μm增强的复合材料的抗拉强度和延伸率大。模拟方面,采用有限元分析软件ABAQUS/CAE,分别建立Ti Ni颗粒呈均匀和随机分布的Ti Ni/Cu复合材料有限元模型,并施加单向拉伸载荷,模拟复合材料受拉应力情况下材料内部应力场分布。分析了增强相的形状、增强相颗粒粒径尺寸、增强体积分数及增强相分布方式等因素对铜基复合材料应力场的影响规律。模拟结果表明:当增强相形状分别为球体、椭球体、正方体、长方体和六棱柱时,球体增强相能在材料内部产生的应力集中最小,对材料增强效果最好,增强相受力由外向内逐渐传递。通过对比纯铜和Ti Ni/Cu复合材料应力分布表明,Ti Ni颗粒的添加,会使的铜基体的各向同性发生改变,应力分布不均,相比纯铜,Ti Ni增强的铜基复合材料力学性能获得提升。当颗粒均匀分布时,通过对比不同Ti Ni粒径增强铜基复合材料的应力场可以得出,Ti Ni颗粒粒径越小,颗粒承受应力越大,对材料增强效果越好;通过分析不同体积分数的Ti Ni颗粒增强的铜基复合材料可知,随着增强相体积分数的增大,增强相承受载荷增大,对材料增强效果越好,但过大的体积分数会使得上下排颗粒间基体产生较大应力集中,一旦超过基体抗拉强度,便会在该处产生裂纹失效。颗粒随机分布时,与均匀分布相似,Ti Ni颗粒粒径越小,增强相体积分数的增大,增强相承受载荷越大,对材料力学性能提升越好。通过对比Ti Ni颗粒均匀分布和随机对力学性能的影响发现:颗粒随机分布时,可能由于某些颗粒距离较近产生应力干涉导致应力集中,因此颗粒均匀分布时产生应力集中更小,且力学性能更高,所以尽量采用某种工艺手段使颗粒均匀分布在铜基体内。更多还原

【Abstract】 Copper-based composites have been widely concerned because of their low strength and poor heat resistance to copper and copper alloys.In copper matrix composites,various kinds of reinforcing phases are introduced into the matrix to obtain better comprehensive properties.In this project,Ti Ni particles with B2 parent phase at room temperature were selected as the reinforcing phase to explore the law of its influence on copper matrix composites.In this paper,Ti Ni/Cu composites were characterized by experimental research and finite element simulation.Obtained by vacuum hot-pressing sintering,the preparation of copper matrix composites,using X-ray diffraction(XRD),scanning electron microscope(SEM),differential scanning calorimetry(DSC)and analytical means such as electronic universal testing machine to strengthen body material and composite material performance testing,after using ABAQUS/CAE software builds finite element model of copper matrix composites,analyzed the Ti Ni reinforced copper matrix composite materials in the process of drawing the internal stress state,in order for the construction of the Ti Ni/Cu composites provides the reference and know.In terms of experimental research,the influence of ball grinding speed and ball grinding time on the mixed powder in the ball grinding process was firstly explored,and the optimal ball grinding process parameters were determined as the ball grinding speed of 200 rpm and ball grinding time of 3 h.Then,Ti Ni reinforced phases with different particle sizes were used to prepare copper-based composites,and their effects on microstructure,phase transition behavior and mechanical properties were investigated.The research results show that: for the composites prepared by vacuum hot pressing sintering,Ti Ni particle reinforcement and Cu will react to form a reaction layer,and the reaction layer Cu:Ti:Ni atom ratio is about 1:1:1.When the particle size was 15-53 μm,the thickness of the reaction layer was about 10 μm.When the particle size was 53-150 μm,the thickness of the reaction layer was about 6 μm.In addition,the one-step phase transition occurred between B2 and B19’ in the process of lifting and cooling.When the larger Ti Ni particles were selected for reinforcement,the phase transition peak of the composite was more sharp,and the phase transition temperature was lower than that of the Ti Ni pre-alloying powder.The stress-strain curve showed that the tensile strength and elongation of Ti Ni with particle size of 15-53 μm were higher than those of 53-150 μm.In terms of simulation,finite element analysis software ABAQUS/CAE was usedto establish the finite element model of Ti Ni/Cu composites with uniform and random distribution of Ti Ni particles,and unidirectional tensile load was applied to simulate the distribution of stress field inside the composites under tensile stress.The influence of the shape of the reinforcing phase,the particle size,the volume fraction of the reinforcing phase and the distribution of the reinforcing phase on the stress field is analyzed.The simulation results show that when the shape of the reinforcing phase is sphere,ellipsoid,cube,cuboid and hexagonal prism respectively,the stress concentration generated by the reinforcing phase inside the material is the smallest and the reinforcement effect is the best,and the stress of the reinforcing phase is gradually transferred from the outside to the inside.By comparing the stress distribution of pure copper and Ti Ni/Cu composites,it is shown that the addition of Ti Ni particles can change the isotropy of copper matrix,and the stress distribution is uneven.Compared with pure copper,the mechanical properties of copper matrix reinforced by Ti Ni can be improved.When the particles are uniformly distributed,by comparing the stress fields of different Ti Ni particle sizes,it can be concluded that the smaller the Ti Ni particle size is,the greater the stress of the particles will be,and the better the strengthening effect of the material will be.By analyzing the different volume fraction of the Ti Ni particulate reinforced copper matrix composites,along with the increase of phase volume fraction,the increase in load bearing,enhancement effect for the materials,the better,but too much will make top and bottom row between particles volume fraction matrix is larger stress concentration,once more than concrete tensile strength and the failure will be there.When the particles are randomly distributed,similar to the uniform distribution,the smaller the Ti Ni particle size,the larger the volume fraction of the reinforcement phase,and the larger the load of the reinforcement phase,the better the mechanical properties of the material will be improved.By comparing the Ti Ni particle uniform distribution and random effect on mechanical properties of discovery: particle random distribution,may cause stress interference at close range for some particles lead to stress concentration,so the smaller particles generated when the uniform distribution of stress concentration,and higher mechanical properties,so try to use some technology to make particles uniformly distributed within the copper matrix.更多还原