Computational and experimental investigation of thermally auxetic multi-metal lattice structures produced by laser powder bed fusion

Communication antennas and optical systems of space-borne satellites require highly accurate relative positioning of components despite large variations in ambient temperature. As a potential solution, additive manufacturing technologies, such as laser powder bed fusion, enable the production of metamaterial structures with complex local geometries that can be designed to achieve the desired thermal and mechanical behaviours. Recent advances enable the processing of multiple materials within a single build to achieve composite structural properties that are infeasible using conventional single materials. This study investigates the potential of tailoring the structural thermal expansion properties of several configurations of a multi-metal re-entrant lattice structure made of stainless steel 316L and the copper alloy CuCr1Zr. Unit cells and lattice structure segments with theoretical coefficients of thermal expansion ranging from 1.64 × 10−5 °C−1 to 2.51 × 10−5 °C−1 (16% more than CuCr1Zr) are evaluated by finite element analysis and validated experimentally. Imperfections related to the manufacturing process are shown to have a significant effect on net expansion. The results indicate good agreement despite the imperfections. The study demonstrates the feasibility of designing and fabricating metal lattice structures for a specific thermal expansion within, as well as above and below, the range of thermal expansion of the parent materials.