Metallic clay

Abstract

From pottery to clay tablets and building materials, clay easily qualifies as one of the most versatile materials in the history of human civilization. Clay owes this versatility to the distinct properties it exhibits before and after firing. Soft, unfired clay can morph into complex shapes, while fired clay offers a fixed shape and higher stiffness. Despite several potential applications, thus far, no designer materials with similar properties have been demonstrated. Here, we introduce the concept of metallic clay: a designer material that mimics the two-state behavior of clay. Metallic clay could initially morph into arbitrarily complex shapes owing to numerous degrees-of-freedom that its various kinematic (moving) and compliant (deformable) joints afford. Once the desired shape is achieved, shape-locking mechanisms (kinematic or compliant) lock the shape of the metallic clay. The fabrication of metallic clay requires novel designs of joints and locking mechanisms that are compatible with metal 3D printing (additive manufacturing) techniques such that metallic clay can be fabricated through a single-step, non-assembly, and self-supporting 3D printing process. We designed with 3D printing 17 prototypes using selective laser melting from a medical grade high strength titanium alloy (Ti-6Al-4V) to demonstrate the various aspects of metallic clay.