Imprinting bias stress in functional composites

TL;DR

The paper introduces a simple method to induce large reversible shape changes in shape memory composites by imprinting bias stress through microstructure conservation, enhancing their functionality without external loads.

Contribution

It presents a novel approach to imprint bias stress in shape memory composites, enabling reversible deformation without training procedures.

Findings

Achieved 0.9% reversible bending deformation in TiNi-based composites.

Demonstrated potential to improve piezoelectric and magnetostrictive composites.

Provided a method to imprint bias stress during fabrication without external loads.

Abstract

We propose a simple yet effective method which allows one to attain large reversible shape changes in shape memory bimetallic composites without training procedure. It is based on the conservation of strongly anisotropic martensite microstructure artificially created in the shape memory layer. This procedure results in appearance of stress field when the shape memory layer is transformed to the austenitic state which brings about two-way shape memory effect. Utilization of this method for preparation of TiNi-based composite with a thickness of 60 \mu m allowed us to achieve 0.9% reversible bending deformation. It is also suggested that the implementation of this method during preparation of piezoelectric or magnetostrictive composites permits to imprint bias stress and thus to improve their characteristics without use of an external load.