Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9803437 | Journal of Alloys and Compounds | 2005 | 4 Pages |
Abstract
The transformation behavior on shock-loaded Ni48Ti52 has been studied by employing a differential scanning calorimeter in order to reveal residual effects of shock treatment in the thermoelastic martensitic transformation of Ni48Ti52, exhibiting a shape memory effect between a high temperature phase and a low temperature phase. The shock treatment of Ni48Ti52 was performed by a flyer plate impact method with the flyer velocity of 1.2 km sâ1. The height of the exothermic and endothermic peaks due to the transformation of shock-treated Ni48Ti52 become small and their temperature regions are expanded. Although the increase of the number of the thermal cycles induces no intermediate phase on Ni48Ti52 before the shock treatment to result in a one-step transformation, a three-step transformation is observed after annealing at an appropriate temperature on the shock-treated Ni48Ti52, which correspond to the appearance of two intermediate phases. The shock treatment increases non-chemical free energy such as strain energy and interfacial energy of a phase boundary, which is attributable to the microstructure of shock-induced dislocations and an increase of the disorder in the lattice of ordered Ni48Ti52, resulting in the three-step transformation. Therefore, it is thought that the shock treatment can make it possible to achieve a new state on NiTi.
Related Topics
Physical Sciences and Engineering
Materials Science
Metals and Alloys
Authors
T. Kurita, H. Matsumoto, K. Sakamoto, H. Abe,