Mechanical Behavior and Structural Characterization of a Cu-Al-Ni-Based Shape-Memory Alloy Subjected to Isothermal Uniaxial Megaplastic Compression.

For the first time, uniaxial megaplastic compression was successfully applied to a polycrystalline shape-memory Cu-Al-Ni-based alloy. The samples before and after uniaxial megaplastic compression were examined by methods of X-ray diffraction, optical, electron transmission, and scanning microscopy. The temperature dependences of electrical resistance and the mechanical properties of the alloys under uniaxial tension were also measured.

New Metastable Baro- and Deformation-Induced Phases in Ferromagnetic Shape Memory NiMnGa-Based Alloys.

Structural and phase transformations in the microstructure and new metastable baro- and deformation-induced phases of the NiMnGa alloy, typical of the unique class of ferromagnetic shape memory Heusler alloys, have been systematically studied for the first time. Phase X-ray diffraction analysis, transmission and scanning electron microscopy, and temperature measurements of electrical resistivity and magnetic characteristics in strong magnetic fields were used. It was found that in the course of increasing the pressure from 3 to 12 GPa, the metastable long-period structure of martensite modulated according to the 10-type experienced transformation into a final non-modulated 2 structure.

Design and Development of Ti-Ni, Ni-Mn-Ga and Cu-Al-Ni-based Alloys with High and Low Temperature Shape Memory Effects.

In recent years, multicomponent alloys with shape memory effects (SMEs), based on the ordered intermetallic compounds B2-TiNi, L2-NiMnGa, B2- and D0-Cu-Me (Me = Al, Ni, Zn), which represent a special important class of intelligent materials, have been of great interest. However, only a small number of known alloys with SMEs were found to have thermoelastic martensitic transformations (TMTs) at high temperatures. It is also found that most of the materials with TMTs and related SMEs do not have the necessary ductility and this is currently one of the main restrictions of their wide practical application.