【作者】 简波；

【导师】 杜随更；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2004， 硕士

【摘要】 为探索一种高效率、低成本制备大块超细晶结构材料的新方法，本文按照摩擦压扭强变形区连续转移的总体思路，提出了两种具体的制备工艺：(1)适用于棒材的摩擦面热诱导转移法，(2)适用于板材的强冷搅拌摩擦工艺。本文从理论上分析了制备过程中热变形参数与工艺参数之间的关系，并采用计算机测试系统检测了制备过程中的工艺参数，讨论了它对摩擦面转移速度的影响。随后分析了细晶材料的外观形貌、金相组织及其透射电镜形态，并测量了细晶材料的宏观和微观硬度、拉伸性能、压缩性能、弯曲性能和阻尼性能。 实验结果表明：(1)通过不平衡冷却的热诱导作用，实现了棒材摩擦界面的持续、稳定转移，得到了棒状超细晶组织；通过强冷搅拌摩擦工艺进行细晶带合并，能够得到板状的超细晶组织。(2)摩擦转速、摩擦压力和变形温度对材料晶粒细化和硬化的影响效果显著。材料热物理性能决定了热诱导试验的参数选择，对于导热性差的材料应选用低转速和大压力。(3)变形温度和变形速率是获得超细晶材料的关键。摩擦面转移速度与输入功率之间存在正比关系。(4)在合适的工艺参数下，上述两种工艺均能够获得亚微米级的超细晶材料。(5)所研究的超细晶材料的硬度、塑性普遍提高，弹性模量有所提高，阻尼性能提高30％～50％，但强度未有明显提高。更多还原

【Abstract】 According to the phenomenon of friction interface transferring, two techniques of processing ultra-fine grain material were advanced to develop new method of preparing large bulk of ultra-fine grain material efficiently and economically. The first is the friction interface thermo-induced transfer method (FITT) for column part, and the second is the cooling friction stir processing(CFSP) for flat part. The relationship between thermo-deformation parameters and processing parameters were discussed. During the preparing course, the processing parameters were collected with computer testing system. And the effect of the processing parameters on the interface transferring velocity was studied. The ultra-fine grain samples were analyzed entirely through its appearance , metallographic structure and SEM appearance; and whose macroscopical hardness(HBS), microscopical hardness(HV), tensile capability , press capability and inflect capability were tested too. In addition, the ultra-fine grain material’s damping capacity were studied as well.The results indicated: 1) The friction interface can transfer continuously and stably with the imbalance cooling thermo-induce. Ultra-fine grain column part can be prepared through it. And ultra-fine grain flat part can be obtained through jointing several ultra-fine grain strips in cooling friction stir processing 2)The refined grain size and the hardening result are mostly affected by the rotate speed, the friction press and the deformating temperature. The thermal conductivity decides the processing parameters choosing for a material, such as a sample material with low thermal conductivity need low rotate speed and high friction pressure. 3) The temperature and the deformation rate are the key factors to prepare ultra-fine grain materials. The interface transferring velocity increases with the input power directly. 4) While the processing parameters are appropriate, both of the indicated techniques can fabricate ultra-fine grain materials successfully. 5) The hardness and plasticity of the prepared ultra-fine grain materials are advanced generally; the elastic modulus is raised slightly; and the damping capacity increases 30~50 percent; however, the improvement in the intension is not distinct.更多还原