Study on the mechanism for pseudo-elasticity effect in Ni-Ti alloy and Fe-based alloys

根据所揭示的形状记忆合金的伪弹性机理，对其伪弹性机理进行了研究，进而考虑了具有该行为的合金。首先，本研究提出了一个简单的无序A2和B2晶体结构的原子间键模型。通过点对称运算发现只有13个图案是唯一的，并根据点群进行分类。根据中心基元与邻近原子基元之间的对称操作，找到了四种键合模式来配置具有独特基元的模型空间。每个形状记忆二元合金都可以通过晶体共形和点对称与原子模型上的基元相连接。其次，用DSC法比较了Ni-Ti合金在变形过程中的应变能与加热过程中的热流应变能，发现两者在平衡处相等。第三，对三种铁基合金进行了弹塑性变形试验，并考虑了其伪弹性。

The mechanism of the pseudo-elasticity is studied according to the revealed mechanism of shape memory alloy and then the alloy having the behavior is considered. First, this study presents a simple interatomic bonding model for disordered A2 and B2 crystal structures. Only 13 motifs were found as unique by point symmetrical operations and classified in terms of the point groups. Four bonding patterns were found for configuring the space of models with unique motifs according to symmetrical operations between the motifs of the center and neighbor atoms. Each shape memory binary alloy can then be connected to the motifs on the atomic model via the crystal syngony and point symmetry. Second, the amount of the strain energy of Ni-Ti alloy during deformation is compared with that of heat flow with DSC during heating and the equality at the balances of both is found. Third, Three kinds of Fe-based alloys are conducted on elastic and plastic deformation tests and considered the pseudo-l asticity.