TSU physicists improved shape memory alloys for space and the Arctic

15 October 2020

The TSU Laboratory of Physics of High-Strength Crystals was the first in the world to obtain an alloy structure that gives them a special ability to deform and restore the original shape by up to 15%. The researchers were able to achieve the maximum values ​​that scientific teams specializing in the development of shape memory alloys are striving for. Materials with a gigantic reversible deformation value are intended for the space industry, robotics, and microsystem technologies.

- Unlike conventional alloys, high-entropy alloys consist of five or more elements taken in equiatomic or equimolar concentrations. This arrangement helps to obtain materials with special functional characteristics, - says Yury Chumlyakov, head of the laboratory. - In the new research project, the laboratory staff worked with Fe-28% Ni-17% Co-11.5% Al-2.5X alloys (X = Ti, Nb, Ta, Ti + Nb). By adding nanoparticles, it was possible to obtain a reversible deformation of up to 13.5%. The maximum calculated deformation resource, to which materials scientists all over the world strive, is 8.7%. TSU physicists are the first to obtain a result that is twice the theoretical resource and to describe the mechanism of this process.

The results of the TSU physicists' research will serve as the scientific basis for creating of new structural and functional materials with high-entropy alloys, adapted for space and the Arctic.

Physicists managed to get even closer to the optimal indicators when working with ferromagnetic alloys NiFeGa (Co) and CoNiAl. Researchers around the world are aiming for 16 %, which is the theoretical deformation resource.

- We managed to achieve 15% - a gigantic deformation in ferromagnetic alloys due to the development of processes of reorientation of the structure of the low-temperature phase under load. We have achieved this process with our patented method  - aging in a martensitic state under load, - says Anna Eftifeeva, a  Laboratory of Physics of High-Strength Crystals staff member.

The high results obtained by the staff of the laboratory on ferromagnetic materials can make the materials suitable for the development of thermally and magnetically controlled force elements used in the space industry and robotics (in mechanisms for fingers or toes of robots, and others). Also, their ability to deform and return to the original state can be useful in fire alarms. When the room temperature rises, the material will change shape and trigger the fire safety system.

An important requirement for the practical application of materials with high reversible deformation is the stability of the reversible deformation value during operation and functional fatigue life. In this regard, the TSU physicists are planning to conduct studies of the cyclic stability of the properties to achieve stable performance characteristics and further introduction of these materials into production.