【作者】 宋伟夫；

【导师】 高后秀；

【作者基本信息】 天津大学 ， 材料学， 2003， 硕士

【摘要】 Cu-Zn-Al形状记忆合金是一种性能优良,造价低廉的功能材料。成分为Cu-Zn26-Al4的合金在高温直接淬火,发生B2→9R马氏体相变,具有很好的形状记忆效应,优于其它成分的同类合金,其微观结构为矛头状马氏体。经过适当的训练可以获得稳定的双程记忆效应,记忆效应下降很小,而且训练的效率很高;但在交变应力下双程记忆效应严重破坏;在室温下长时间时效没有马氏体稳定化现象,具有实用价值。Cu-Zn-Al合金中存在着未被人们发现的另一种相变过程,称为类流态相变。发生类流态相变的胞区往往伴有晶格的转变,不同相之间的转换。温度、应力的变化以及电场、磁场能够诱发类流态相变。X-ray衍射图谱中的峰高发生明显变化,证明相变过程发生。测量胞区硬度随应力变化的分形维数,证明该相变过程符合分形特征。对不同时刻的胞区的灰度值进行采样,应用相位随机化方法可以证明存在混沌运动。利用薛罗根模型及非线性动力学方程可以在理论上证明这种相变过程是在临界点附近由外界条件改变引起的自组织现象。更多还原

【Abstract】 Cu-Zn-Al shape memory alloy is a kind of function material with fine performance and low cost. The alloy with the composition of Cu-Zn26-Al4 quenched at high temperature directly has fine shape memory effect and its shape memory effect is better than other alloy with similar composition. The microstructure is pick-like martensite. After training, the alloy can gain stable two-way shape memory effect, the descend of SME is little and the training efficiency is high. Under alternating stress, the two-way shape memory effect is heavily destroyed. Aging at room temperature, there is no stability of martensite. The alloy has utility value.There is an unknown transformation process in Cu-Zn-Al alloy named quasi-fluid transformation. Quasi-fluid cells’ crystal lattice and phase will change when transformation happen. The change of temperature or stress and the load of electric field or magnetic field will induce this kind of transformation. The obvious change of height in X-ray diffraction pattern proved the happen of transformation. Sampling on the gray of cells at different moment and using phase randomization theory can prove the existence of chaos movement. Using Schlogl model and non-linear dynamic equation, we can prove theoretically that this kind of transformation is a self-organization phenomenon caused by the change of environment at critical point.更多还原