Coupling thermodynamic simulation and thermal analysis to select Sn–Bi alloys for semisolid additive manufacturing

One of the most used additive manufacturing (AM) techniques is fused filament fabrication (FFF), which is primarily used for processing polymers. An interesting strategy to utilize this technique in metal processing is to adapt semisolid processing principles. Herein, low-melting Sn–Bi alloys were investigated to identify the ideal composition and processing conditions for semisolid AM using FFF. For this purpose, thermodynamic simulations were used to characterize the evolution of liquid fractions with temperature, and the results led to the selection of Sn-38Bi alloy (mass/%) for experimental validation. This composition was prepared by casting in an inert environment, followed by thermal analysis. The differential scanning calorimetry results were reasonably consistent with the simulated results. The as-cast Sn-38Bi was extruded to produce a metallic filament. To investigate the microstructural evolution in the semisolid state, samples from the filament were subjected to multiple heat treatments at different temperatures. Semisolid AM for the selected alloy was successfully performed at 170 °C. This process included extrusion and deposition without nozzle clogging or discontinuity formation. Various geometries were successfully fabricated, and the results demonstrated the efficacy of the FFF technique for processing metallic materials. Graphical abstract