Scalable Solid-State Additive Manufacturing of Metal Matrix-Shape Memory Ceramic Composites

Donald J. Erb1, Hunter A. Rauch1,†, Hang Z. Yu1*

1 Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA.

† Present Address: Applied Research Laboratory, Pennsylvania State University, State College, PA 16804, USA.

* Corresponding Author: hangyu@vt.edu

Abstract

Shape memory ceramics exhibit outstanding shape memory and superelastic performance, with high recoverable strain and energy dissipation density. However, achieving these functionalities at bulk scale is challenging due to their brittleness and large shear strain during martensitic transformation. Recent advances in mesostructure engineering offer novel solutions to this problem by connecting shape memory ceramic building blocks through optimal topological designs (e.g., foams and honeycombs) or weak constraints (e.g., composites and granular packings). Among these, metal matrix-shape memory ceramic composites are particularly promising, as they provide a balance of load-bearing capacity and functional responses to external stimuli. Here, we present a scalable approach for solid-state additive manufacturing of such composites, achieving full density and well-dispersed shape memory ceramic particles in the as-deposited state. This is accomplished by integrating additive friction stir deposition with feedstock engineering, where extensive metal flow around the ceramic particles ensures porosity elimination at the particle-matrix interface, and mechanical stirring promotes particle dispersion. We demonstrate this manufacturing strategy based on ZrO2-CeO2 shape memory ceramics constrained by aluminum or copper, with ceramic loadings up to 20 vol%. For the first time, stress-induced martensitic transformation is observed in bulk-scale ZrO2-CeO2-metal composites. The fraction of transformation continually increases with applied load, and post-compression heating effectively recovers the original phase. Thermally induced forward and reverse martensitic transformations are shown under various mechanical constraints, with meso-scale martensitic transformation investigated via Raman spectroscopy mapping. Offering a low-cost and low-energy pathway, this work opens new possibilities for the practical utilization of shape memory ceramics in large-scale applications with scalable manufacturing.

 

Keywords: Shape memory ceramics; solid-state additive manufacturing; metal matrix composites; stress-induced martensitic transformation; mechanical constraint; scalable manufacturing