The Department № 70 “Physics of solid state and nanosystems” successfully continues study of alloys with a shape memory. These materials are recognized as one of the most promising for the use in devices of micro-electro-mechanical systems (MEMS) such as micro-valves, micro-grippers, micro-pincers and micro-drivers, which use thin films and ribbons. Results of MEPhI scientists are reflected in the article N. Resnina, S. Belyaev, A. Shelyakov, Pseudoelasticity effect in amorphous – crystalline Ti40.7Hf9.5Ni44.8Cu5 shape memory alloy // Smart Mater. Struct. 24 (2015) 045013 (8pp). (IF 2.735) http://www.sciencedirect.com/science/article/pii/S0921509315000039.

Professor of the Department №70 Alexander Shelyakov told about this promising research:

– Alloys with shape memory are widely used in various fields of engineering because of their unique ability to recover the deformed state when heated (shape memory effect) or at discharge (effect of pseudoelasticity).

This functional behavior of alloys with shape memory occurs due to thermoelastic martensitic transformations in it. In the last 15 years, these materials were recognized as one of the most promising for use in devices of micro-electro-mechanical systems (MEMS) such as micro-valves, micro-grippers, micro- pincers and micro- drivers, which use thin films and ribbons. At the same time it was found that functional properties of these objects (thin films and tapes) differ from the properties of bulk alloys with the same chemical composition.

As a rule, the structure of films and tapes is amorphous after production, and it is needed to hold crystallization of the alloy, which forms the ultra-fine grain structure with an average grain size less than one micron. At the same time the average grain size in the bulk alloys based on titanium nickelide is tens of microns.

Varying crystallization parameters it is possible to obtain objects with various structure parameters (grain size and grain distribution) and, as a result, they have different functional properties. In addition, the controlled crystallization allows to obtain samples with amorphocrystaline structure. The aim of this work is to study the effect of pseudoelasticity in amorphous-crystalline thin ribbons made of the alloy Ti40.7Hf9.5Ni44.8Cu5 with different volume ratios of the crystalline phase.

Read other results obtained by MEPhI in the study of alloys with shape memory in the following publications on the website.