Solid-state additive manufacturing of shape-memory ceramic reinforced composites

Abstract

We report a solid-state additive manufacturing route for producing shape-memory ceramic (Zr_0.88Ce_0.12O₂) reinforced metal matrix composites. Using additive friction stir deposition, we implement two feedstock engineering strategies: (i) pre-mixing of powders using a Cu matrix and (ii) hole-pattern drilling using an Al-Mg-Si matrix, where the specific matrix materials are chosen for their distinct shear flow behaviors. The process yields fully dense composites with uniform particle dispersion (20 vol%) and dynamically recrystallized metal matrices. The severe thermomechanical processing conditions also reduce the ceramic particle size, resulting in unique composite microstructures unattainable by alternative processing routes. The as-printed composites can withstand high compressive loads without cracking and retain functionality enabled by thermally and mechanically triggered martensitic transformations. Notably, for the first time, stress-induced martensitic transformation (tetragonal to monoclinic) is observed in bulk-scale composites—but it is only present in the Cu matrix composite, not the Al-Mg-Si counterpart. Micromechanics modeling attributes this contrast to differences in the load transfer and strain hardening capabilities. Complementary to global transformation characterization, Raman mapping reveals that transformation typically initiates at the particle-matrix interface. Together, these results establish a potential pathway for scalable manufacturing of multi-functional metal–shape memory ceramic composites with tunable microstructures and transformation responses.