【作者】 陈湜；

【导师】 朱和国；

【作者基本信息】 南京理工大学 ， 材料学， 2009， 硕士

【摘要】 本文运用放热弥散反应法（XD法）合成Al-ZrO₂和Al-ZrO₂-B系铝基复合材料。根据热力学基本理论对反应过程进行热力学分析;采用金相显微镜、SEM和XRD等现代手段分析反应产物及其微观组织;结合DSC（Differential Scanning Calorimetry）曲线对反应过程进行动力学分析;研究不同工艺参数对反应过程及其结果的影响;并测试材料的常温力学性能,探讨其强化机理和断裂机制。机理研究表明:在Al-ZrO₂系中,随着温度的增加,Al液化并与ZrO₂形成液—固界面,当温度升至830℃左右时,界面处反应生成热力学稳定的α-Al₂O₃和活性Zr原子,α-Al₂O₃与液态Al润湿性差,偏聚于反应界面,阻碍Zr原子的扩散;Zr原子在反应热和浓度梯度的作用下扩散进入Al基体,反应生成Al₃Zr。Al-ZrO₂-B反应系中,加入的B首先与Al在700℃结合生成AlB₂,升温至840℃左右时,与ZrO₂结合反应生成α-Al₂O₃和ZrB₂,抑制Al₃Zr形成,B/ZrO₂摩尔比为2时,Al₃Zr基本消失,反应产物仅由α-Al₂O₃和ZrB₂组成;由升温速率分别为10℃/min、20℃/min和30℃/min的DSC曲线和Kissinger方程,计得Al-ZrO₂的反应活化能为358 kJ/mol,B/ZrO₂摩尔比为1时,反应活化能升至393 kJ/mol。性能研究表明:增强相体积分数为20%和30%的复合材料,随着B/ZrO₂摩尔比由0增至1和2时,拉伸强度先降后升,分别由135MPa和186MPa降至130MPa和163MPa后又升至189MPa和209MPa。延伸率却随之先增后降,分别从4.7%和14.9%增至10.3%和16.1%后降至8.1%和12.3%。Al-ZrO₂,Al-ZrO₂-B系复合材料的强化机理为弥散强化、细晶强化、位错强化,断裂机制有位错机制和空位形核机制。更多还原

【Abstract】 In this article,Al-ZrO₂ and Al-ZrO₂-B systems aluminum matrix composites were fabricated by means of exothermic dispersion（XD）.Thermodynamic analysis of reaction process was carried out.The reaction products and microstructures of composites were analysed by modern means such as optical microscope（OM）,scanning electron microscopy （SEM）,and X-Ray diffraction（XRD）.The kinetics of the reaction process was investigated based on DSC and the influence of different technical parameters on the reaction process and results;the normal temperature mechanical performance was tested and its strengthening mechanism and fracture mechanism were explored.The study of mechanism shows that:with the raise of temperature,Al liquefied and formed fluid-solid interface with ZrO₂;when the temperature reached 830℃,α-Al₂O₃,which has stable thermodynamic properties,and active Zr atoms were produced.In Al liquation, owing to its poor wettability,α-Al₂O₃ particles were prone to segregate at the interface and hindered Zr atoms’ dispersion;however,with the effect of concentration gradient and heat,Zr atoms diffused into Al matrix and then Al₃Zr generated.In Al-ZrO₂-B system,firstly B reacted with Al at 700℃to form AlB₂;as warming up to 840℃,AlB₂ reacted with ZrO₂ to generateα-Al₂O₃ and ZrB₂,which inhibited the formation of Al₃Zr.When B/ZrO₂ molar ratio was 2,Al₃Zr basically disappeared in the matrix;the reaction product only consists ofα-Al₂O₃ and ZrB₂.The activation energy value of Al-ZrO₂ system calculated from DSC curves with different heating rates and the Kissenger equation was shown to be 358 kJ/mol. When B/ZrO₂ molar ratio is 1,the activation energy rise to 393 kJ/mol.The research of mechanical properties shows that:as B/ZrO₂ molar ratio grew from 0 to 1,further to 2,the tensile strength of the composites whose reinforcement volume fraction were 20%and 30%firstly decrease from 135MPa and 186MPa to 130MPa and 163MPa respectively,but then rose to 189MPa and 209MPa.However,the elongation rate varied in the opposite way,increasing from 4.7%and 14.9%to 10.3%and 16.1%at first,and then falling to 8.1%and 12.3%.The strengthening mechanism of Al-ZrO₂ and Al-ZrO₂-B systems composites can be interpreted by dispersion strengthening,fine grain strengthening, dislocation strengthening;the fracture mechanism include dislocation nucleation mechanism and the vacancy mechanism.更多还原