Engineers develop a new kind of shape-memory material

Amazing stuff!

"Shape-memory metals, which can revert from one shape to a different one simply by being warmed or otherwise triggered, have been useful in a variety of applications, as actuators that can control the movement of various devices. Now, the discovery of a new category of shape-memory materials made of ceramic rather than of metal could open up a new range of applications, especially for high-temperature settings, such as actuators inside a jet engine or a deep borehole. ...
Now, the MIT team has found a way to overcome that and produce a ceramic material that can actuate without accumulating damage, thus making it possible for it to function reliably as a shape-memory material through many cycles of use. ...
The hysteresis changed so dramatically that it now resembles that of metals ..."

From the abstract:

"Zirconia ceramics exhibit a martensitic phase transformation that enables large strains of order 10%, making them prospects for shape-memory and superelastic applications at high temperature. Similarly to other martensitic materials, this transformation strain can be engineered by carefully alloying to produce a more commensurate transformation with reduced hysteresis (difference in transformation temperature on heating and cooling). However, such ‘lattice engineering’ in zirconia is complicated by additional physical constraints: there is a secondary need to manage a large transformation volume change, and to achieve transformation temperatures high enough to avoid kinetic barriers. Here we present a method of augmenting the lattice engineering approach to martensite design to address these additional constraints, incorporating modern computational thermodynamics and data science tools to span complex multicomponent spaces for which no data yet exist. The result is a new zirconia composition with record low hysteresis of 15 K, which is about ten times less transformation hysteresis compared to typical values (and approximately five times less than the best values reported so far). This finding demonstrates that zirconia ceramics can exhibit hysteresis values of the order of those of widely deployed shape-memory alloys, paving the way for their use as viable high-temperature shape-memory materials."

Engineers develop a new kind of shape-memory material | MIT News | Massachusetts Institute of Technology The ceramic-based material could be used for highly efficient actuators for aircraft or other uses, with minimal moving parts.

Low-hysteresis shape-memory ceramics designed by multimode modelling (no public access)