【作者】 孙晓光；

【导师】 姜龙涛；

【作者基本信息】 哈尔滨工业大学 ， 材料物理与化学， 2008， 硕士

【摘要】 本文采用压力浸渗法制备了体积分数为27%、33%和40%的TiB_2P/6061Al复合材料和TiB_2P /2024Al复合材料,对复合材料进行热挤压加工。利用扫描电镜（SEM）、透射电镜（TEM）、拉伸试验等多种分析测试手段对复合材料的微观组织、力学性能进行了系统的研究,探讨了增强体含量、热处理工艺对热挤压前后复合材料力学性能的影响。研究表明:TiB₂颗粒在基体中的分布随着颗粒体积分数的增加而趋于均匀。挤压后复合材料组织致密,颗粒分布均匀。TEM观察表明,TiB₂颗粒与基体合金界面结合状况良好,有轻微的界面反应,TiB₂颗粒附近基体中存在由热错配产生的位错;热挤压可明显细化基体晶粒,挤压后的晶粒尺寸为1³μm,TiB_2P/6061Al复合材料的时效析出相为β′相;TiB_2P/2024Al复合材料的时效析出相为S′相,且后者的时效后析出相细小弥散。压力浸渗法制备的TiB_2P/6061Al和TiB_2P/2024Al复合材料的抗拉强度、屈服强度和弹性模量均随TiB₂颗粒体积分数的增加而获得提高,TiB_2P/2024Al复合材料的抗拉强度在380MPa至550MPa之间,体积分数40%的TiB_2P/2024Al的抗拉强度可达550MPa,经热挤压之后,复合材料的力学性能获得进一步的提高,TiB_2P/2024Al复合材料的抗拉强度在410MPa至580MPa之间,体积分数40%的TiB_2P/2024Al挤压热处理之后的抗拉强度可达580MPa以上。而复合材料的延伸率随着颗粒体积分数的增加逐步下降,挤压后复合材料的延伸率还是随着颗粒体积分数的增加而下降,但较挤压之前有很大提高,尤其是体积分数40%的TiB_2P/6061Al的延伸率较挤压前提高了100%。三种体积分数TiB_2P/6061Al复合材料和TiB_2P /2024Al复合材料断口分析表明,复合材料的断裂方式为微观上基体铝合金的韧性断裂特征,且随着体积分数的增加,复合材料体积分数的提高,由宏观上的塑性断裂转变为脆性断裂的特征。更多还原

【Abstract】 TiB₂ particles reinforced 6061 aluminum matrix composites and TiB₂ particles reinforced 2024 aluminum matrix composites which volume fraction are 27%,33% and 40%, which were fabricated by pressure infiltration technique, then were extruded on the hot extrusion process. The effects of reinforcement, heat treatment and hot extrusion on microstructure characteristics, tensile properties, were studied by using of SEM, TEM, tensile testing machine.Results indicate that the particles tend to uniformity with the volume fraction increased of the particles. The composites are dense and reinforcement particles distribute uniformly after hot extrusion. The TiB₂-Al interface combined well, and there are slight reactants on the interface and some dislocations in the matrix alloy beside TiB₂ particles caused by mismatch stress; sub grains are found after hot extrusion, and grain size are refined to 1³μm, the precipitation of TiB₂/6061Al areβ′;the precipitation of TiB₂/6061Al are S’,and the fine S’there are dispersive in the matrix alloy.The tensile strengths、yield strengths and elasticity modulus of TiB_2P/6061Al and TiB_2P/2024Al are increased with the volume fraction increased of the particles .The tensile strengths of TiB_2P/2024Al which volume fraction is 40% is 550MPa, the mechanics properties of the composites which extruded are more strength than which unextruded , the tensile strengths of TiB_2P/2024Al which volume fraction is 40% after hot extrusion in T6 state are 583MPa. The elongation ratios of the composites are descend with the volume fraction increased of the particles , the elongation ratios of the composites which extruded are descend with the volume fraction increased of the particles, but the elongation ratios which extruded are increased compare with unextruded composites respectively, the elongation ratios of TiB_2P/6061Al which volume fraction is 40% is increased 100%.Fractographic analysis of the three volume fraction of TiB_2P/6061Al and TiB_2P/2024Al composites indicates that the fracture of composites is toughness fracture of the matrix alloy in microstructure, but the fracture of composites is brittle fracture with the volume fraction increased.更多还原