【作者】 刘先兰；

【导师】 胡治流；

【作者基本信息】 广西大学 ， 材料加工工程， 2006， 硕士

【摘要】 等径角挤压(ECAP)技术是通过大塑性变形，获得大尺寸亚微米或纳米级块体材料的有效方法之一。但是，ECAP超细晶材料的结构均匀性依赖于所应用的工艺方案、材料的原始结构等诸多因素，尚未找到一条最佳的ECAP工艺路线；对不同材料的变形工艺参数的选择与优化等缺乏全面的研究；对晶粒细化机制的研究有待进一步深入。根据ECAP的基本理论和目前国内外研究成果，系统分析了等径角挤压过程中的工艺参数如模具结构及尺寸、挤压次数、挤压路径、挤压速度、挤压温度和摩擦系数等对ECAP法制备超细晶材料组织结构及性能的影响。 本文选用铝及铝合金的细化剂Al-5Ti-B作为ECAP变形试样材料进行实验。确定合适的ECAP工艺参数，设计制造了模具。在不同工艺路线条件下进行ECAP实验，观察Al-5Ti-B变形过程中组织和性能的变化，测定Al-5Ti-B应力应变曲线，确定工艺参数对组织和性能的影响，探讨了ECAP过程中Al-5Ti-B合金的超细化组织的演化规律。 同时，利用ANSYS软件进行有限元模拟，对Al-5Ti-B的ECAP变形规律和组织演化规律进行了分析。通过理论分析和有限元数值模拟，探索了ECAP法制备块体超细晶材料的最佳工艺路线。更多还原

【Abstract】 Equal channel angular pressing technology (ECAP) provides an effective procedure for obtaining the bulk sub-micrometer or nanometer scale materials by sever plastic deformation. However, the best process has not been found in technique since the structural homogeneity of the ultra-fine grained materials depends on the applied technologic processes and the original structures of materials and so on.An overall investigation on the choices and optimization of technologic parameters for different materials is still lacking. And the mechanisms of grain refinement need to be put forward further.According to the fundamental theories and the latest research progress, we analyze systematically the influences on microstructures and properties of the ultra-fine grained materials caused by technologic parameters such as structure and dimensions of ECAP dies, the number of pressing ,the routes of ECAP, the velocities , temperature and the friction states of the ECAP.Al-5Ti-B alloy, one kind of grain refiners for aluminum and aluminum based alloys, was used as the experimental object of ECAP experiment. By the experiment the optimizing technologic parameters were determined and the corresponding die was designed and manufactured. By performing the experiments in different technologic processes, we observed the changes of microstructures and properties, measured the stress-strain curves and beat out the influences of technologic parameters on microstructures and properties in the deformation. Then the evolution of ultra-fined structures of the object was discussed in the experiment.Meanwhile, the deformation and the structural evolution in the ECAP were更多还原