Viewpoint: Tuning the Martensitic Transformation Mode in Shape Memory Ceramics via Mesostructure and Microstructure Design

摘要

The shape memory and superelastic effects are based on mechanically or thermally induced martensitic transformation. In bulk monolithic shape memory materials, these effects are characterized by a driving force threshold, such as a critical stress or a critical temperature, above which the transformation is completed within a relatively narrow window of stress or temperature. In this viewpoint article, we discuss the tuning of macroscopic martensitic transformation characteristics via mesostructure and microstructure design: with heterogeneous driving force and low nucleation barrier in meso-/micro-structured shape memory materials, especially shape memory ceramics, local transformation events can occur sequentially rather than simultaneously. This can lead to a globally continuous transformation mode without well-defined critical stress or temperature. Based on the insights from mechanics modeling and experimental evidence, we illustrate this effect in granular packings, metal matrix composites, and cellular architectures, and discuss how it may unlock new possibilities for applications involving actuation and energy dissipation.