Realizing reversible phase transformation of shape memory ceramics constrained in aluminum

Abstract

Small-scale shape memory ceramics exhibit superior shape memory or superelasticity properties, while their integration into a matrix material and the subsequent attainment of their reversible tetragonal-monoclinic phase transformations remains a challenge. Here, cerium-doped zirconia (CZ) reinforced aluminum (Al) matrix composite is fabricated, and both macroscopic and microscopic mechanical tests reveal more than doubled compressive strength and energy absorbance of the composites as compared with pure Al. Full austenitization in the CZ single-crystal clusters is achieved when they are constrained by the Al matrix, and reversible martensitic transformation triggered by thermal or stress stimuli is observed in the composite micro-pillars without causing fracture in the composite. These results are interpreted by the strong geometric confinement offered by the Al matrix, the robust CZ/Al interface and the local three-dimensional particle network/force-chain configuration that effectively transfer mechanical loads, and the decent flowability of the matrix that accommodates the volume change during phase transformation.

Shape Memory Polyurethane Composite With Fast Response to Near‐Infrared Light Based on Tannic Acid–Iron and Dynamic Phenol‐Carbamate Network

“…Upon reheating the material to the melting temperature again, the internal crystals begin to melt, the forces stored in the molecules are released, and ultimately, enabling it to recover its original shape in the absence of external forces. [13,14] It is worth noting that shape memory polyurethanes (SMPUs) have advantages over other SMPs because of their tunable characteristics that can be modified by changing the molecular weight, the type of hard segment or soft segment, or their ratio. [15] However, although thermally induced SMPUs have the advantages of convenience and cost-effectiveness, their broader application is limited by heat loss and the inability to precisely control the heating during the process.…”