Scientists Create New Smart Shape Memory Materials
Scientists at Moscow's National Research Nuclear University MEPhI and the National University of Science and Technology MISiS have created new functional materials from shape memory alloys, which can be used to create a variety of microdevices for medicine, space and aircraft construction.
The results of the study were published in the journal Materials.
Experts have noted that the obtained alloy is one of the smart materials with superelasticity and shape memory effect (SME), which after large deformations (up to 14%) can return to its pre-deformed shape when heated.
It was possible to obtain a unique material made of TiNiCu alloy with high Cu content using methods of combined extreme influence of ultra-fast cooling from liquid state and megaplastic (severe) deformation.
According to the scientists, studies of recent years have shown that the key to obtaining new unusual properties of materials is the creation of unique structural conditions using an intense impact on solid bodies.
Such materials in their limit states are the latest achievements in materials science and are widely used in robotics, aviation and space technologies, power engineering, instrument engineering, biomedicine and biotechnology.
“As a result of ultrafast quenching with the melt cooling rate of about one million degrees per second, we have obtained ribbons from alloys of the TiNi-TiCu system with high copper content from 30 to 50 micrometres thick in the amorphous state in the form of metallic glass”, an associate professor of the Solid State Physics and Nanosystems of MEPhI Institute for Laser and Plasma Technologies, Alexander Shelyakov said.
The obtained rapidly quenched TiNiCu alloy thin ribbons proved to be a very promising material for the creation of miniature high-speed devices, as they are characterised by narrow hysteresis of SME manifestation.
“Next, we used high-pressure torsion (HPT) method. Samples of amorphous ribbons were placed between two anvils and compressed under giant pressure. The lower anvil rotated, and the sample was deformed by shear under the action of surface friction. Since deformation occurred under conditions of compression and torsion at the same time, the sample did not fail, but was subjected to megaplastic deformation,” Alexander Shelyakov said.
According to the scientists, this opens the door for the development of innovative functional materials with high SME characteristics and homogeneous submicro- and nanoscale structure. This will help to create many micro-devices: micro forceps, microvalves, micro clamps and micro-drives for such relevant areas as microbiotechnology or technologies of micro-nanoelectromechanical systems.