A paradigm shift towards compositionally zero-sum binderless 3D printing of magnesium alloys via capillary-mediated bridging

Abstract Several metallurgical issues arise during melting and solidification-based additive manufacturing (AM) methods which limit their use to only a few alloys. This study shows how capillarity-driven bridging can serve as a new and rapid tool of assembling powder particles into 3D structures providing the least metallurgical complexity. According to the established conceptual framework, in-situ binding agent can be derived autogenously from selective interactions of a liquid solvent with superficial layer of powder particles to form in-situ solid interparticle bridges which enables AM at ambient conditions. Magnesium (Mg) is the most difficult engineering metal to handle in all 3D AM processes in view of its intrinsic properties. Supported by transmission and scanning electron microscopies together with Fourier transform infrared and Raman spectroscopy, the introduced 3D printing concept is readily accomplished for Mg alloys by conversion of MgO film, inevitably existing on the outermost layer of Mg powder, into interparticle bridges. In the absence of pyrolysis-adapted sintering profile, these bridges fully decompose during the following sintering step which result in functional Mg parts with chemical composition same as the starting Mg powder with zero contamination, according to chemical and thermal analysis results. The introduced capillary-mediated binding of particles is simple and generic that could be extended to additively manufacture other metals, ceramics and found applications in other traditional ex-situ binder-based processes.